Geo-Congress 2024: Soil Improvement, Sustainability, Geoenvironmental, and Cold Regions Engineering

Seepage control is a key concern for excavation or other types of underground construction. Although several methods have been adopted including chemical grouting, we still need methods that can reduce the permeability of sand and control seepage in a quicker and more cost-effective way. One of the potentials is gelation method. By introducing alginate solution underground in sand layer and producing calcium ion underground at the same time, hydrogel can be formed to occupy the pores in sand. In this way, the permeability of sand can be much reduced to achieve the seepage control purpose. In this paper, some experimental results on the hydrogel formation procedures and permeability reduction effect are presented. A small-scale model test was also conducted, and the results of this model tests are given as well. This study has shown that gelation can be an effective and yet inexpensive method for seepage control, which can drastically reduce the permeability of sand from the magnitude of 10⁻⁴ to 10⁻⁷ m/s. However, this method suffers from other limitations too such as durability. The advantages and disadvantages of the proposed method are discussed as well.

Enzyme-induced calcium precipitation (EICP) is a promising technique for soil improvement. EICP utilizes enzymes to induce the precipitation of calcium carbonate (CaCO₃) within soil pores, enhancing their mechanical properties. This study investigates the potential of using iron oxide (Fe₂O₃), aluminum oxide (Al₂O₃), and zinc oxide (ZnO) nanoparticles to enhance the performance of EICP-treated sands in acidic and alkaline environments. The pH, unconfined compressive strength (UCS), and calcium carbonate content of treated specimens were evaluated. Results showed that ZnO nanoparticles diminished the EICP effect, while Al₂O₃ nanoparticles improved UCS by 6.4% at a concentration of 0.20%. Fe₂O₃ nanoparticles retained 28.5% and 13.7% of UCS at concentrations of 0.10% and 0.40%, respectively. The addition of nanoparticles reduced the calcium carbonate content, with ZnO-EICP showing the highest reduction (~90%). This research highlights the need for further enhancement of the EICP technique in acidic and alkaline environments.

Coastal dunes are protective structures and shield coastal communities and infrastructure from inundation, particularly during intense storms. However, the buildup of wave-induced pore water pressure in sandy soil can lead to localized regions of liquefaction, ease soil particles to detach, and facilitate erosion, ultimately causing failure. A two-dimensional sand profile has been numerically modeled and subjected to repeated wave loading to investigate the wave-induced pore pressure regime in the soil. Oscillatory and residual soil responses are the causes of pore pressure in the soil during storms. The oscillatory pore pressure is due to the water pressure fluctuation at the seabed under the wave loading and can cause momentary liquefaction. Due to wave-induced cyclic shear stress, the principal stress orientation rotates continuously and can accelerate plastic deformations and, therefore, buildup residual pore pressure. This study used equilibrium and continuity equations, including a source term, as the governing equation for predicting the residual and oscillatory components’ pore water pressure due to repeated wave loading. As bio-mediated soil improvement techniques are being adopted to improve the shear strength and stiffness of soil, the microbially induced calcite precipitation (MICP) treatment was applied to the surface of the soil to reduce the impact of wave-induced instability of the slope. This study incorporated bio-cementation parameters into the equations mentioned above to capture the pore pressure response within the treated soil. The numerical results indicate that the bio-treated layer decreases the upward pore pressure gradient in the susceptible region close to the ground surface. Moreover, due to shear strength improvement, the rate of pore pressure generation in treated soil is significantly lower than in untreated soil.

Expansive soils pose a serious challenge to civil engineering constructions due to their ability to swell and shrink upon wetting and drying. This phenomenon usually leads to damage of the structure when the soil is not treated properly. Moreover, the disposal and utilization of fly ash (FA) in both economical and eco-friendly ways has received high attention in the world. Thus, this study focuses on the improvement of the geotechnical properties of expansive soils stabilized with varying percentages of fly ash as an admixture. In the present study, low calcium fly ash in different proportions by weight (0%, 10%, 20%, 30%, and 40%) was added to a moderately expansive soil collected from Doharramafi Village, India. Laboratory tests performed on the prepared mixtures included the determination of moisture-density relationships, California bearing ratio (CBR), and shear strength parameters. Test results show that moisture-density relationships, CBR values, and shear strength parameters of fly ash-treated soil are significantly modified and improved compared to control specimens. Furthermore, based on all laboratory tests, 30% fly ash content is observed to be the optimum fly ash quantity required to improve the geotechnical properties of soil stabilized with fly ash.

Liquefaction is a geohazard causing loss of lives and infrastructure around the world. Liquefaction results from a sudden increase in excess pore-water pressure (EPWP) in loose, saturated, noncohesive, and fine soils. Due to the small size of pores and relatively low hydraulic conductivity of these soils, the induced EPWP throughout shaking does not have enough time to dissipate before the soil liquefies. If a soil’s hydraulic conductivity could be increased during seismic shaking, the shaking time would be ample for soil to afford for EPWP dissipation. A potential theory, introduced by our research team, is that electromagnetic (EM) waves can increase granular soils’ hydraulic conductivity. This increase can potentially lead to liquefaction mitigation. This research examines the relationship between hydraulic conductivity and EPWP buildup, evaluates EM waves’ impact on the EPWP buildup via altering hydraulic conductivity, and evaluates the potential of EM-induced liquefaction mitigation.

In this study, the behavior of a single stone column under axial loading was investigated through field tests and numerical modeling. The stone column was installed for a water conveyance project located at a coastal site near the Persian Gulf in Iran as part of a rectangular column group consisting of columns having a 0.8 m diameter and a center-to-center column spacing of 2.0 m. Columns were installed using the vibro-replacement technique to a depth of 12 m. Time was allotted to allow for the dissipation of construction-induced pore pressures, and three small plate load tests were performed to measure the stress-settlement response of one of the columns. A quasi-static procedure that regularizes unstable behavior was adopted to analyze the load-settlement behavior of the axially loaded stone column. The procedure was validated by modeling an experimental result from a previously published study using axisymmetric 2D finite element analyses. Using the validated quasi-static procedure, 2D and 3D finite element models were then developed to simulate the results of the plate load tests on the stone column constructed using the vibro-replacement method. The validated 3D FEM model was then adopted to perform a series of parametric analyses and further investigate the effect of surrounding soil shear strength, the ratio of stone column diameter to spacing, and the strength of column materials. The results showed that the strength of the surrounding soil had more effect on limiting axial stress than either the replacement ratio (s/d) or the strength of stone column materials. The results of the parametric analyses were then compared with available analytical solutions. The comparison indicated that one approach closely matched the finite element modeling results, while another overestimated the ultimate bearing capacity, revealing that a satisfactory analytical method is not available for a wide range of conditions.

Chemical treatment of expansive sulfate-rich soils, particularly lime- and cement-based methods, has been rather popular in practice due to its relatively low cost and ready availability of these chemical additives. The present work was aimed at gaining crucial insights into the potential effects of lime- and cement-based treatments on the stiffness and damping properties of sulfate-rich clayey soils. To this end, a series of resonant column (RC) tests were conducted on chemically stabilized specimens of a highly plastic, sulfate-rich clay from Sherman, Texas. RC test results were analyzed to assess the influence of chemical stabilizer dosages, curing times, and confining pressures on the small-strain shear modulus (G_max), small-strain damping ratio (D_min), and normalized shear moduli (G/G_max) of treated soil. Chemical treatments included 3% cement + 2% fly ash, and 6% lime + 4% fly ash. Test results show a detrimental effect of cement + fly ash treatment method on soil stiffness, rendering 6% lime + 4% fly ash as a potentially feasible method with curing times longer than 14 days.

Cone penetrometer tests (CPTs) have been extensively used for sinkhole geotechnical investigation, especially in regions with bedrock in deeper burial depth (such as East Central Florida). One common method to mitigate potential sinkholes is through grouting. However, the determination of grouting volume is very challenging. The sinkhole resistance ratio (SRR), developed from CPT data as an index to better understand the state of raveling and sinkhole susceptibility, can be used to help identify grouting volume potential. In this study, two approaches were taken to explore the correlation between SRR values predetermined at the existing sinkhole sites and grout intake volumes: (1) through a site-wide grouting index (GI), and (2) based on individual CPT location and localized grouting volumes. This study was applied to various sinkhole locations throughout Central and Northern Florida. Based on the dataset, approach 2 using individual CPT locations provided a better correlation between the SRR value and grout volume. Using a logarithmic trend, it was shown that as the SRR value decreased, there was an exponential growth in grout volume used.

Coastal embankments in Bangladesh have been suffering from repeated damages due to frequent floods and cyclones over the last few years. Stabilizing embankment soil is essential to mitigate these damages and attain sustainability. This study used the PAM additive as the primary stabilizing agent. Additionally, other stabilizers, that is, cement and fly ash, were mixed in different ratios with PAM to study its combined effect on enhancing soil’s physical and strength properties. Untreated soil samples were collected from the coastal area of Chattogram, Bangladesh, and were treated in the laboratory with PAM and other stabilizers with different mixing ratios. A series of geotechnical laboratory tests, that is, Atterberg limit tests, Proctor compaction tests, unconfined compressive strength (UCS) tests, etc., have been performed in a sequence on treated and non-treated soil samples to study the effectiveness of the stabilizers. The optimum mixing ratios of different stabilizers are selected by considering the workability and strength enhancement of treated soils. Various methods to prepare treated samples have been studied in detail. Variations in results have been observed while treating the soil in powder and solution forms of admixtures. The investigation shows that both workability and strength should be considered when selecting the soil and admixture ratio. The research outcome of the study also indicates that the soil’s physical and strength properties improved when the stabilizers were used as a combination of different mixing ratios rather than using the PAM alone.

Liquefaction-induced settlement due to earthquakes can cause significant damage to supported infrastructure, with the settlement mechanisms mobilized depending on the characteristics of the soil profile, ground motion, and structure. Microbially induced calcite precipitation (MICP) has been shown to mitigate liquefaction and reduce settlements in previous centrifuge studies. This study conducted a series of 1-m centrifuge tests at the University of California, Davis (UCD) Center for Geotechnical Modeling (CGM) to evaluate soil-structure interaction (SSI) of a simple foundation system on loose Ottawa F65 sand (D_r < 40%) with a finite MICP-treated zone. A simple rigid structure, designed to be susceptible to rocking when subjected to a 1-Hz motion, was used. A high-speed camera motion tracking system was developed to measure the lateral and vertical movements of the structure during shaking. This non-contact system eliminated all instrumentation physically connected to the structure, which ensured that the measurement system did not affect the structure performance. Accelerometers and pore pressure transducers were embedded within the underlying soil to capture the dynamic system response. Results show how a finite MICP-treated zone beneath a structure can help reduce the structure settlement and loading experienced.

Reuse of mine tailings is a growing area of research, and one possible reuse strategy is the creation of geopolymer bricks. Geopolymerization uses a strong alkaline solution to break down the source material into alumina and silica monomers, which are then consolidated and cured into a strong, solid sample. However, a well-known and existing challenge in performance of tailings-based geopolymers is the poor hydrolytic stability (i.e., durability in water). To improve this property, a high temperature treatment was applied to geopolymers made from 85% gold mine tailings and 15% fly ash type F. The geopolymer bricks were heated to 600°C for 6 h, which densified the pore structure and improved the performance of samples in water. The compressive strength retention was improved from 55% to 83%, and samples exhibited nearly zero mass loss during water immersion for seven days. This technique can be generalized to geopolymers made from any type of low-reactivity source material, though further testing is needed to determine the beneficial effect for other mix designs.

Reinforcing soil with natural fibers is perceived as sustainable and effective ground improvement technique. Wide-ranging researchers tackled the investigation of the undrained behavior of fiber-reinforced clays that targets only the short-term stability of geotechnical systems that are built utilizing fiber-reinforced clays, neglecting the long-term performance. There is a need for exploring the response of fiber-reinforced clays under fully drained conditions where long-term stability considerations govern the design and particularly expand the knowledge on the response of natural fibers within a drained testing setting whereby durability issues might affect the response of the composite. The objective of this paper is to investigate the durability of hemp fibers for long-term stability applications involving compacted clay systems. These objectives are achieved by conducting a total of six consolidated drained triaxial tests on fiber-reinforced natural clayey soil specimens compacted at 18% water content with 4-cm-long fibers and 1.25% fiber content by weight and one control sample. Results of durability tests indicated that the improvement in strength due to the addition of hemp fibers is lost for specimens that are allowed to cure for three weeks prior to drained testing.

Dynamic replacement (DR) and rapid impact compaction (RIC) are techniques to improve the geotechnical properties of in situ soils. Dynamic compaction has been extensively used to improve the artificial islands constructed with hydraulic fills; however, the efficacy of a combination of DR and RIC has not been reported for hydraulic fills of artificial islands. This paper presents the results of ground improvement from simultaneous use of DR and RIC in improving the granular fill of a 45,000 m² area of an artificial island near Ras Al-Khaimah in the United Arab Emirates (UAE). The lower granular fill is improved with DR, whereas the second layer is improved with RIC. A series of field tests such as cone penetration test (CPT) are conducted before and after the improvement. The results of the field tests show that the DR as well as RIC caused significant improvement in physical properties of the compacted soils and the desired improvement is achieved within the influence zone of the planned structures at the required depths.

In slope stability, weak layers are thin layers of low-strength materials which can potentially form part of the critical sliding surface. The search for the critical slip surface in slope stability is a complicated optimization problem that minimizes the factor of safety by altering the parameters corresponding to the geometry of a slip surface. While searching for the critical slip surface, it is important to fully consider the weak layers in a model. Traditionally, slope stability programs have handled weak layers by clipping the slip surfaces, which are generated during the automatic searching stage, to the weak layers. If multiple weak layers touch a slip surface, there are multiple permutations of clippings that can be performed on the slip surface by the weak layers using any, all, or none of those weak layers. As such, it can become very difficult to identify which combination of the weak layers would produce the lowest factor of safety. In this paper, a new method is proposed which efficiently considers the contribution of each weak layer via an additional optimization parameter. The proposed approach is demonstrated via an example and is shown to be relatively faster in speed against leading industry methods, while maintaining comparable accuracy.

A large-scale bio-cementation experiment was conducted to evaluate the feasibility of microbially induced calcite precipitation (MICP) using a bioaugmentation approach with Sporosarcina pasteurii for improving the sub-structures of existing asphalt and concrete roadways. A 1.2 m × 1.2 m soil filled reactor was used, containing a 23-cm-thick layer of sand treated with five injection ports, spaced 0.3 m apart. The sand layer was sandwiched between two layers of coarse gravel, with a 2.5-cm thick grout slab on top, simulating the impermeable road surface. The MICP treatment was applied daily over 8 days. To monitor improvement, biogeochemical changes were assessed by collecting fluids from the reactor through four ports at the corners of the model. Changes to the mechanical properties were monitored both spatially and temporally using California Bearing Ratio (CBR) through testing ports on the surface. A pasteurizing waste treatment system was developed to deactivate the bio-waste. This paper outlines the design and construction of the sand box and discusses the method development. Further details will be provided regarding the injection strategy and treatment process.

This paper evaluates the performance of supervised machine learning (ML) algorithms in predicting standard penetration test (SPT) N-values. The study utilized drilling response measurements (DRM) collected from the installation of rigid inclusions at a highly heterogeneous municipal solid waste (MSW) site. A range of ML algorithms were evaluated in this paper, including linear regression, decision trees, random forests, support vector machines, gradient boosting, and artificial neural networks. The ML algorithms were trained and evaluated on DRM data along with SPT boring data available for the project. The results of this study showed that ML algorithms can be used to predict SPT N-values to give rudimentary information about the relative density of the soil from DRM data.

Construction of geotechnical structures over soft foundation soils is an incredibly challenging task due to the risk of bearing failure and excessive settlement of foundation soil. Recycled plastic pin (RPP) has been used as a noble approach to improve the problematic foundation soil by increasing the bearing capacity of the foundation. The objective of the study was to evaluate the vertical load bearing capacity of individual RPPs by conducting field load tests using plate load tester. In this study, vertical pile load tests were conducted on individual RPPs of two different sizes (10 cm by 10 cm and 15.24 cm by 15.24 cm), and six empirical methods were used to investigate the ultimate load bearing capacity of RPPs. Based on the load settlement behavior obtained by the field load test results, the vertical load bearing capacity of 10 cm RPP ranged from 30 to 45 kN (settlement of 1 to 1.6 cm). On the other hand, 15.24 cm RPP had vertical load bearing capacity of 89 to116 kN with corresponding settlement of 1.2 cm.

Geo-structures, like MSE wall constructed over weak soil, are prone to base sliding failure, which causes failure in the long run. Recycled plastic pins (RPPs) can be a viable and sustainable solution for increasing the lateral resistance of the foundation system. The objective of the present study is to evaluate the lateral resistance of RPPs in terms of load deflection behavior by conducting field load tests. In this study, RPPs of two different sizes were driven into high plastic clay at three different embedment depths and were laterally loaded to failure or until excessive deflection occurred. Based on the load deflection behavior obtained by the field load test results, the 10 cm-by-10 cm RPPs had lateral load bearing capacity ranging from 16 to 28 kN. On the other hand, lateral load bearing capacity of 15.24 cm-by-15.24 cm RPPs was found to be in the range of 29 to 40 kN. It was observed that lateral load capacity increased 40% to 80% as RPP size increased, and deflection increased from 20% to 50% as embedment depth decreased.

Laboratory evaluation of the bio-cementation effect of lateritic soil using MICP was carried out to determine the overall acceptable zone (OAZ) for its use. Lateritic soil was treated with B. megaterium up to 24 × 10⁸ cells/ml over a range of moulding water contents (MWCs) from dry to wet sides of optimum moisture content (OMC) (i.e., −2%, 0%, +2%, and +4%). The soils were compacted with four energies [i.e., reduced British Standard light (RBSL) (Reduced Proctor), British Standard light (BSL) (Proctor), West African Standard (WAS) (Intermediate), and British Standard heavy (BSH) (Modified Proctor)]. The hydraulic conductivity (k ≤ 1.0 × 10⁹ m/s), volumetric shrinkage strain (VSS ≤ 4%), and unconfined compressive strength (UCS ≥ 200 kN/m²) values that represent the design parameters for construction of liners and covers in MSW containment facilities were determined. It was found that lateritic soil treated with B. megaterium suspension density of 2.4 × 10⁹ cells/ml prepared with MWC in the range 14.4%–16.4% and compacted with at least BSL energy is within the OAZ and satisfies landfill containment design criteria.

The use of biological methods to improve the mechanical characteristics of geomaterials has gained popularity recently. The utilization of the enzyme “urease,” when produced by a microbe, which causes the breakdown of urea and leads to the precipitation of calcium carbonate (CaCO₃) when mixed with calcium, is known as microbially induced calcium carbonate precipitation (MICP). MICP is a promising approach for surface soil strengthening. Previous studies have shown that finer soil contents can affect the uniformity of bio-cementation distribution through the soil sample, and thus its strength properties. The objective of this study was to analyze bio-cementation via MICP in various sand mediums, ranging from coarse to fine particle size and ranging from uniformly to well-graded. Sakrete medium commercial sand, Ottawa sand, and silica silt were used at different percentages to produce samples for treatment. Results conclude that well-graded sand compositions created stronger, more brittle samples than compared to poor-graded compositions and larger particle sand sizes. Additional testing needs to be done on finer sand particles as well as current sands to verify previous results before further testing can be done on varying soil compositions.

Biological techniques for enhancing soil quality have gained attention as sustainable and long-lasting solutions for soil improvement. One such technique is enzyme-induced calcium precipitation (EICP), which involves the use of ureolysis to precipitate calcium carbonate (CaCO₃) in soil. This paper explores the potential of EICP as a soil improvement technique and investigates the use of sodium alginate (SA) biopolymer to enhance its effectiveness. The durability of SA-assisted EICP-treated sand is assessed through various durability tests, including wetting-drying cycles, sulfate resistance, and the effects of curing and drying temperatures. The results provide insights into the long-term performance of polymer-assisted EICP soil treatment.

Slope instability-related damage is a major issue all over the world, including Bangladesh. Every year, slope failure occurs all over the country and causes major financial losses. A variety of methods are available for addressing this issue, but conventional slope protection methods require large and long-term investments. Hard engineering solutions can also be temporary, only transferring the problem from one location to another. A viable solution to this problem may be to use bio-engineering technology applying vegetation. Vegetation as a bio-engineering technique for slope stabilization can improve the shear strength and reduce the erosion potential of soils. The objective of this study is to evaluate the effectiveness of vegetation in improving the shear strength of soil. Vetiver grass which is a commonly found in Bangladesh was selected for the study. Roots were collected from uprooted vetiver grass found in a naturally grown land. To prepare the root-reinforced soil samples, roots were chopped according to different lengths (1.25–5 cm) and mixed in different root content (3%–12% of the dry weight of the soil sample) and moisture content of soil (10%–25%). It was observed that root-reinforced soil samples have a maximum of 88.2% higher shear strength compared to root-free samples. The added cohesion of vetiver rooted soil has a positive correlation with the root length, but for the root content shear strength increases up to an optimum root content and then decreases. The results from the present study have also been compared to the previous studies and found in good agreement with each other.

The particle migration phenomenon in porous media during fluid injection is influenced by various factors such as drilling mud composition, particle properties, fluid flow, and porous medium characteristics. Further, this process is predominantly governed by hydrodynamic forces acting on the porous granular medium in addition to the in situ stress state, rheology of the injecting fluid, and constriction size distribution. During fluid injection, the void spaces of the porous medium are filled by the particulates present in the suspension, leading to the obstruction of flow paths. Thus, the overall porosity is reduced, and the hydraulic conductivity decreases as a result of the time-dependent filtration process. In this study, the filtration process is examined by means of a specially designed laboratory experimental setup, with the collection of filtrates resulting from the injection of drilling fluid at a constant pressure. Furthermore, the flow properties of these filtrates are quantified at different time intervals during the experiments to gain an understanding of the impact of particle migration on the filtration process. The characteristic features (viscosity, storage modulus, and shear modulus) of the filtrates at different filtration times are provided by the experimental investigation. Notably, these findings reveal a shift in the fluid properties of the filtrates toward the continuous phase, specifically water. Moreover, it is determined that the effective filtration time for the specific composition of drilling fluid is approximately 30 min, and it is significantly influenced by the properties of both the drilling fluid and the porous medium.

The occurrence of secondary compression is a peculiarity of soils rich in organic matter derived from plant remains. The ratio of secondary compression to primary compression (C_α/C_c) has been considered a valid parameter for predicting secondary compression behavior in peats or organic soils. In the present study, a low organic soil sourced from the Kuttanad region of Kerala State, India, has been studied for its consolidation characteristics. The inclusion of chitosan for the modification of compressibility is a novel method as it contributes to the recycling of 8 million tonnes of crustacean wastes yearly. One-dimensional fixed ring consolidation tests were conducted on samples treated with chitosan (at 0.5%, 1%, 2%, and 4% dosages added by dry weight of soil) and prepared at optimum moisture content (OMC) and maximum dry density (MDD) conditions. The increase in chitosan concentration reduced the compression index by 78% for 2% amended samples at a consolidation pressure of 50 kPa. With an increase in consolidation pressure up to 800 kPa, C_c increased indicating higher stiffness of the soil matrix. At 50 kPa, C_α declined to 0.007 for 2% and 4% chitosan which falls outside the normal range of organic soils. The variation in C_α/C_c was marginal with an increase in consolidation pressure and fell in the range of 0.03–0.05 at 2% chitosan which indicated the transformation of soil into inorganic material. The scanning electron microscopic images revealed that a flocculated and aggregated soil structure was observed with chitosan treatment up to 2% dosage. However, the higher concentration of chitosan particles led to aggregation with soil particles and resulted in interaggregate voids. Based on the study’s findings, crustacean biopolymers stipulate detailed research to explore their suitability for soil amelioration.

DSM (deep soil mixing) is a flexible approach of soil improvement. Soft clays, silts, and fine-grained sands are among the soils that this method can help stabilize. The binder factor (BF) is the ratio of the weight of dry binder to the volume of soil to be treated, and it varies between 150 and 700 kg/m³ for conventional ordinary Portland cement (OPC), with clayey soils requiring a higher BF. Because cement manufacturing accounts for 8% of global carbon dioxide emissions, reducing the carbon footprint of cement usage is becoming more significant. As a result, a major increase in the use of low-carbon binders is expected on the road to long-term ground improvement. The current study shows early laboratory testing using a new addition to minimize cement content in the mix design while maintaining the mechanical properties. CEM I and CEM III cements were used in this study, and unconfined compressive strengths (UCS) tests were carried out at 28 days. The use of a calcium silica hydrate nanoparticle reduced the binder factor (BF) from 220 to 140 kg/m³ while maintaining strength properties over the baseline condition. The carbon footprint was also calculated and showed a potential reduction in CO₂ savings greater than 50%.

In recent years, microbially and enzyme-induced calcite precipitation (MICP and EICP) have gained traction as ecologically friendly methods for stabilizing soils. More recently, using the concepts associated with MICP and EICP, “bioslurry” was developed. Bioslurry is very similar to traditional MICP, but calcium and urea are added to the initial bacterial solution. In this study, several Florida soils were treated with bioslurry using a combination of techniques, ratios of bioslurry to cementation solution, and solution concentrations. Specifically, two soils were examined—beach sand and soil with high organic content. Beach sand specimens were treated via a surface percolation technique and subject to erosion testing using a pocket erodometer. Soils with high organic content were treated using a hand mixing technique and were tested for unconfined compressive strength. In addition, preliminary X-ray diffraction analysis was conducted on treated specimens to characterize crystallization. Regardless of soil-type or test-type, results appeared to indicate that optimization was achieved when approximately 25% of the specimens’ pore volumes were filled with bioslurry and 75% of their pore volumes were filled with cementation solution (i.e., calcium plus urea) and that at this approximate optimization point, soil properties were improved.

Hurricane storm surges can significantly damage transportation infrastructure and consequently hinder access routes for relief and quick recovery of the affected communities. Problematic coastal soils are often weak in strength and stiffness and highly erodible, which causes distress to the pavements and arterial roads after flooding events. As a result, enhancement of the engineering properties of such weak soils is essential to provide resilient coastal infrastructure systems. A research study was designed to assess the efficacy of calcium-based stabilizers including lime and cement on the strength, stiffness, and erodibility characteristics of coastal soils. Laboratory studies were conducted on natural sandy and clayey soils as well as 7-day cured cement-treated sandy soil and 14-day cured lime-treated clayey soils to evaluate the improvements in resilient modulus, unconfined compressive strength, and erodibility. Specimens were also tested after soaking in the water bath for 6 and 24 h to replicate storm surge aftereffects. Test results indicated that the application of stabilizers significantly increased the strength and stiffness values for treated clayey and sandy soils. The treated clayey soils retained an average 150% higher strength after moisture conditioning and also recorded an average of 60% less degradation in the resilient moduli values as compared to untreated soils. Similar results were also observed for cement-treated sandy soils. The stabilized specimens also illustrated a reduction in the erodibility coefficient, from 0.1 to 0.02 cm³/N-s in lime-stabilized clay and 8 to 0.007 cm³/N-s in cement-stabilized sand. Consequently, the behavior of the natural soils changed from erodible or very erodible soils to resistant or very resistant soils after chemical stabilization. Overall, the study provides a comprehensive understanding of the efficacy of calcium-based stabilizers in improving the resiliency of transportation infrastructure, which could extend the service life and provide quick recovery from coastal hazards.

Installation of urban piles presents a number of difficulties in terms of noise, vibration, and impact on adjacent structures. The environmentally friendly ground improvement technique known as “biopolymer-based soil treatment” (BPST) is being actively considered in both academic and real-world settings. It is expected that the shear thinning properties of biopolymer hydrogels lessen frictional resistance during pile movement. In addition, trivalent ion-induced crosslinking between soil particles and xanthan gum biopolymer hydrogel improves the interaction between the soil and the pile after pile installation. Through these properties, in this study, the pile skin resistance reduction and pullout resistance enhancement effects induced by biopolymer hydrogel injection and subsequent crosslinking have been assessed. The interface direct shear test was conducted to evaluate the interface shear behavior between sandpaper and soil/treated soil. The model pile was pulled out to evaluate the load carrying capacity of the pile. The load carrying capacity of the biopolymer-treated pile was the smallest. Also, piles in sand and crosslinked biopolymer-treated piles exhibited similar load-displacement curves, especially in the initial displacement. However, in the residual state, the resistance of the pile in the crosslinked biopolymer-treated sand was higher. Through the experimental results, the feasibility of applying biopolymer to increase installation efficiency is reviewed. In addition, it was found appropriate to use the crosslinking method to increase the load carrying capacity.

Geotechnical engineers encounter several challenges in infrastructure development due to the presence of black cotton soil in the field. Black cotton soil contains a higher percentage of montmorillonite and provides low bearing capacity, high shrinkage, and high compressibility. Various ground improvement techniques are adopted to enhance the strength of these soils. Chemical treatment is one of the most important and widely adopted methods for ground improvement of high plastic clays. Alkali-activation of the geomaterials leads to the formation of various compounds that provide strength due to geo-polymerization. Utilization of kaolin serves two purposes, that is, reduction in the formation of shrinkage cracks and increase in the availability of alumina content to enhance the process of geo-polymerization. There is no study available on the geopolymerization of black cotton soil, which includes the influence of the kaolin content and alkali concentration. In this work, the shear strength of the black cotton soil and kaolin-amended black cotton soil was performed using unconfined compressive strength (UCS) tests. The UCS tests were conducted on black cotton soil amended with different percentages of kaolin using different concentrations of alkali (NaOH) under controlled curing conditions. Controlled curing refers to the heating of samples at 40℃ or 60℃ for the desired duration. The study considered the 5M, 7.5M, and 10M of NaOH, and 5%, 7.5%, and 10% of kaolin for amendment of black cotton soil. The results of the study showed the use of a sustainable binder to improve the shear strength of the black cotton soil.

Microbially induced calcite precipitation (MICP) or biocementation is a bio-mediated process that can be used to improve the engineering properties of granular soils through calcium carbonate precipitation. Although most commonly this process is accomplished using microbial urea hydrolysis, other microbial metabolic pathways can be used to enable biocementation with the potential to eliminate ammonium byproducts. Microbial organic acid oxidation presents one alternative pathway by which increases in solution carbonate species can be generated to enable calcium carbonate mineral formation. While past studies have considered the potential of this microbial pathway to enable biocementation for surficial applications, to date few studies have examined the feasibility of this pathway for subsurface applications wherein dissolved oxygen is more limited. In this study, 18 small-scale batch experiments were performed to investigate the ability of microbial organic acid oxidation to enable biocementation soil improvement. Experiments investigated the feasibility of using both acetate and citrate oxidation to mediate biocementation as well as the effect of differences in techniques used to supply dissolved oxygen, the effect of supplied growth factors, bicarbonate salt additions, and solution sampling frequency. Results suggest that aerobic oxidation of acetate and citrate can be used to enable calcium carbonate biocementation, though ensuring dissolved oxygen availability appears to be critical towards enabling this process.

Colloidal silica (CS) is a non-toxic soil stabilization solution with proven effectiveness against liquefaction in both laboratory and field tests. Specifically, CS treatment has been shown to increase unconfined compressive strength with time. However, limited knowledge exists regarding the performance of CS-treated soils after 1,000 days post treatment. This paper presents UCS test data for CS-treated sand samples of varying ages (freshly made and preserved since 2009). The fresh samples were prepared to replicate 2009 sample conditions by mixing poorly graded concrete sand, colloidal silica (5%–9% concentration), and NaCl accelerator (0.3N–0.45N). Additionally, scanning electron microscopy tests were performed to support result interpretation and monitor microstructural changes over time. The preliminary results from this study comparing freshly prepared versus the oldest known CS-treated sand specimens advances understanding of colloidal silica microstructure evolution and prediction of unconfined compressive strength over time.

One practical approach to directly lessen our reliance on natural resources is using industrial wastes as construction material. This frees up significant spaces that are otherwise needed for storage and disposal. It also has the potential to enhance the applicability of water-sensitive clayey soil as a construction material. This study examines two industrial wastes, Jarosite waste from the zinc industry and red mud from the aluminium industry, as unconventional stabilizers for highly clayey soil. A comprehensive geotechnical investigation on clayey and treated soil samples has been carried out, considering time effects. The lightweight compaction method and maximum unconfined compressive strength for 7 and 28 days of the curing period have been used to determine the optimum mix for the clay-waste blend. Strain-controlled cyclic triaxial experiments have been performed on clayey and treated soil samples at axial strain amplitudes of 0.2%, 0.4%, and 0.6% with a loading frequency of 1 Hz. The results show that the unconfined compressive strength of the treated sample rises by about 57% to 123%, compared to virgin soil, after 0 to 28 days of curing. The free swell index value decreases to 10% from 44%, and swelling pressure drops to 9.1 from 95.5 kPa for treated samples after 28 days of curing.

Basic oxygen furnace steel slag (BOFSS) has been widely investigated for its use in both bound and unbound pavement layers. BOFSS particles entail both volumetrically unstable components and heavy metals. In this study, a volumetrically stable mixture that contains 80% BOFSS and 20% FFA by weight (BOFSS20FFA) was produced and tested. Basic characterization tests (i.e., specific gravity, sieve, and hydrometer) were performed on the BOFSS and BOFSS20FFA mixture. Compaction behavior and the permeability of the mixture were assessed. The corrosion potential of the mixture was evaluated through pH and electrical resistivity tests. The results of the leaching tests performed on BOFSS and FFA samples used in this research study were also evaluated. The dry unit weight of BOFSS20FFA was higher than that of BOFSS, corresponding to a lower optimum moisture content. The hydraulic conductivity of BOFSS20FFA was close to fine-grained soils due to the increased fines content and inter-particle cementation. pH measurements and electrical resistivity tests on the samples indicated the relatively high corrosion potential of BOFSS20FFA. The leachate analysis on BOFSS indicated that heavy metal concentrations in the leachate for almost all metal parameters tested (except chromium) were within the acceptable limits of generally accepted local and international drinking water standards. On the other hand, the results obtained for FFA were well above the limits of drinking water standards. These results showcase the importance of FFA selection in the geo-material mixture designs. As the heavy metal concentration depends on various site-dependent factors, pH-dependent advanced laboratory tests and field tests are required to better understand the environmental impacts of using mixtures.

This paper evaluates three ground improvement techniques used in engineering practice: (1) press-in sheet piles around the foundation, (2) lowering groundwater level (GWL) by 1.5 cm, and (3) a combined approach. The objective is to investigate their effect on excess pore water pressure (PWP), foundation settlement, and tilting, and propose technically sound and economically viable measures. In this study, a series of moderate scale 1-g shake table experiments were conducted at the University of Nevada, Reno, to evaluate the performance of those techniques in liquefiable soils. A 1/5 scaled model consisting of three soil layers with varying densities, namely the crust, liquefiable, and dense layers, was prepared, and a shallow foundation was placed over the crust layer. The proposed ground improvement techniques were then applied to the model ground, which was excited using a shaking duration of 13 s and a PGA of 0.28g. Experiments showed that all the mitigation measures reduced the foundation settlement and tilting and generated excess PWP. Among the three ground improvement techniques, the combined technique proved most effective, reducing excess PWP by 74%, and foundation settlement and tilting by 87% and 95%, respectively. These findings offer valuable insights for engineering practice in mitigating liquefaction-induced foundation settlements.

The performance and longevity of lightweight infrastructure depend on the engineering behavior of the underlying soil. Such infrastructure systems typically do not perform satisfactorily when built on expansive soils owing to the moisture-induced volume change characteristics. Lime stabilization has been successfully used worldwide to address the problems associated with expansive soils. However, lime treatment is often ineffective when the expansive soil has appreciable soluble sulfates. This research study has been designed to assess the scope of utilizing a novel admixture derived from quarry fines to suppress sulfate heaving in an expansive soil having a sulfate content of 20,000 ppm. Strength testing, before and after capillary soaking, and one-dimensional free swell tests were conducted on cured chemically treated specimens to evaluate the moisture-induced strength loss and volume-change characteristics of the problematic soil. Different dosages of quarry fines (QF) (0%, 15%, and 30%) were considered to assess the efficacy of the novel admixture in mitigating ettringite-induced heaving. Supplementary mineralogical and micro-structural analyses using X-ray diffraction, scanning electron microscopy imaging with energy dispersive X-ray spectroscopy, and differential thermal analysis were used to understand the underlying causes of the observed changes in engineering properties. These test results were analyzed to investigate the role of co-additive dosage and curing period on the efficacy of the novel admixture. Test results indicate that the quarry fines can effectively suppress ettringite-induced heaving when used as a co-additive with lime stabilizer; the benefits are pronounced at higher dosages and after longer curing periods.

The State Pier Complex is being redeveloped into an offshore wind support port that will become the first operational United States-based port of its kind. The site is uniquely positioned for the deployment of wind turbine installation vessels and offers the size and configuration that is sought after for these types of terminals. Redevelopment includes the creation of a single, large pier by constructing a new bulkhead between the existing piers and infilling between them, demolition of existing structures, construction of two heavy-lift relieving platforms that will support loads of up to 5,000 pounds per square foot (psf), and construction of several other new bulkhead walls. This paper presents the site history, subsurface conditions, construction, and geotechnical engineering challenges associated with the project.

The offshore wind industry increasingly turns to floating platforms in deeper waters due to their consistent wind resources and site suitability. This shift, however, demands cost-effective and robust anchors capable of handling heavy loads. While steel has traditionally been the go-to choice, concerns about its supply chain and environmental impact have arisen. As a result, the industry is exploring alternative materials that align with sustainability criteria and site-specific factors, such as turbine size and lifespan. Potential substitutes include carbon fiber-reinforced polymers (CFRP), high-strength concrete, and other metals. These alternatives offer benefits such as corrosion resistance, reduced CO₂ emissions, and enhanced strength-to-weight ratios. This study delves into how the choice of anchor material influences design optimization to meet load capacity requirements. Its findings aim to guide the selection of the most suitable anchor material, taking into account economic considerations and environmental concerns. By optimizing both design and material selection, the offshore wind industry can achieve cost-effective and eco-friendly solutions for its floating platforms, addressing the challenges of today’s energy landscape.

Wetlands act as a line of defense against the increasing impacts of hurricane storm surge and waves, rising sea levels, and the effects of changing weather patterns. Evaluating the wetland soil-root matrix shear strength is challenging due to both the complex nature of roots and the differences in live biomass and necromass volume with depth. Reasonable estimates of the root matrix shear strength in a horizontal mode of shear were developed using a large-scale direct shear apparatus (LDSA). Test beds for this study are the Atchafalaya and Terrebonne Basins in Louisiana; three sites were selected per basin across a salinity gradient of fresh to saline marsh. Initial findings indicate that the stress-displacement response witnessed an upward curvature. This behavior is attributed to the effect of the longitudinal and diagonal roots on the shear strength of the soil-root matrix when the shear plane cuts along the roots.

Conventional methods for recovering methane gas from natural hydrate-bearing sand (HBS) involve dissociating the hydrate, impacting the mechanical properties of the HBS. Existing numerical models used for predicting ground behavior over long-term production are calibrated based on laboratory tests conducted after hydrate formation and not dissociation as limited research studies have been conducted to comprehensively understand the changes in HBS shear strength during dissociation. In this research, experiments were conducted on laboratory-synthesized HBS specimens that had undergone hydrate dissociation to varying degrees by thermal stimulation as well as depressurization revealing notable reductions in both stiffness and peak strength. These observed alterations in mechanical properties commenced within the confines of the bulk hydrate stability region, suggesting the influence of sediment grain size and pore diameter. Further studies aim to explore the other contributing factors to these observations.

Bentonite-polymer composites (BPC) have been developed for use in waste and chemical containment applications where barriers comprising traditional sodium bentonite (NaB) are likely to undergo adverse chemical interactions that degrade barrier performance. Previous research has indicated BPC can maintain low hydraulic conductivity, k (e.g., k < 10⁻¹⁰ m/s) even when in contact with solutions of high ionic strength, extreme pH, and/or multivalent species, such that diffusion remains the dominant mechanism by which contaminants transport through the barrier. However, diffusion properties of BPC can be highly variable and are not yet fully understood. Further, diffusion testing on BPC can be challenging to perform, limiting available data. In this study, diffusion tests were performed on a range of BPC specimens using calcium chloride (CaCl₂) source solutions to evaluate potential correlations between measured solute diffusion coefficients (D_a) with index test properties that are simpler to measure. The index tests included cation exchange capacity (CEC), liquid limit by fall cone penetration (LL), and active water content (AWC). The four different materials evaluated were all commercial BPCs containing NaB that had been amended (via dry mixing) with either 4% or 8% anionic polymer (by weight). The preliminary results confirmed that index test results may be useful for predicting diffusion behavior of BPC. For example, there was an inverse relationship between D_a and AWC for all materials. However, the best empirical correlations between measured D_a and corresponding BPC index properties (R² ≈ 0.7) were relationships that combined all three parameters (CEC, LL, and AWC). Additional data points are needed to further refine such correlation and will be the focus of subsequent experimental research. The ability to estimate BPC diffusion coefficients from index test results when a diffusion testing program is not feasible can improve the prediction of long-term containment barrier performance and support BPC selection for site-specific conditions.

Climate change has resulted in accelerated permafrost thawing, which wreaks havoc on infrastructure in the Arctic such as pipelines, buildings, and roads. The thawing permafrost can have remarkable impacts on the mechanical behavior (e.g., bearing capacity and settlement) of pile foundations supporting Arctic infrastructure. This study was carried out to investigate the effect of warming on the behavior of pile foundations in frozen soils by performing axial loading and creep tests of model piles in a frozen soil-pile interaction lab at Clarkson University. A soil box of 1.38 m in length, 0.90 m in width, and 1.22 m in height has been built in a cold room. The air temperature in the cold room can be regulated from −50°C to 75°C to produce temperature cycles or freeze-thaw cycles of the soils using a programmable temperature control system. A model pile was installed in the soil box with a diameter of 63.5 mm, and length of 81.0 cm. In this study, axial load capacity and creep test were conducted to evaluate the behavior of the pile installed in frozen sandy soil. The axial load capacity of the model pile was 87 kN based on the quick test. Creep settlements of the pile subjected to a constant load of 10 kN were measured as the temperature of the frozen soil gradually increased from −8.20°C to −0.15°C to simulate the effects of warming. The creep rate was 0.007 mm/day when the temperature changed from −8.0°C to −1.0°C, but progressively increased to 1.787 mm/day at −0.20°C. This observation is presented in detail in this paper and underscores the importance of understanding pile foundation behavior in response to rising soil temperatures.

After several extreme natural disasters, such as earthquakes, hurricanes, and floods, huge trees are still alive and standing while manmade infrastructure has collapsed and failed. The natural foundation adopted by nature for supporting trees is significantly different from those constructed for supporting manmade infrastructure. Therefore, a new, economical foundation configuration can be developed by studying the tree root system. This study is part of a significant effort to understand the root configuration and load transfer mechanism using three-dimensional finite element modeling to develop innovative foundations for infrastructure systems. Specifically, in this study, the mechanical properties of roots from several trees were measured in the laboratory, and the results are reported. To accomplish this, three common tree species in the Southeastern United States were selected: pine, sweetgum, and white oak. Different-sized tree roots were collected from all interested tree species and were modified to make cylindrical samples with varying diameters and constant heights. The samples were then tested in a laboratory under compressional axial loading. The results show that the varying diameters of the samples have a correlation for the white oak roots: as the diameter increased, the compressional elastic modulus decreased. However, this was not evident for the pine and sweetgum samples. Also, the white oak roots had the largest compressional elastic modulus, followed by the pine and sweetgum roots, respectively. From the stress-strain plots, the sweetgum roots were determined to be the most ductile, followed by the white oak roots; therefore, the pine roots were the most brittle. Also, the stress-strain plots show that the white oak roots had the maximum peak and yielding stress values of the tested tree species, followed by pine and sweetgum, respectively. Finally, the failure mode was important to note while testing the root samples. These failure modes were generalized into two main categories: buckling and shearing. The main failure mode for the white oak and sweetgum roots was buckling, while shearing was the main failure mode for the pine roots. However, there were other important observations noted during testing and discussed in this study.

The Downtown Redmond Link Extension project is a major extension of the regional light rail system within the Puget Sound area of Washington State. Because of the prevailing site conditions and design philosophy as well as the shallow groundwater and flat topography, managing stormwater was a major design element of the project and required a complex system of collection and distribution network of infiltration facilities. Careful analyses and design were therefore necessary for creating the infiltration system to manage stormwater using multiple facilities in a highly developed area with a shallow groundwater table while mitigating adverse impacts of flooding. The stormwater management solution achieved in this project illustrates a successful outcome from a close and continuous coordination among geotechnical, civil, and stormwater engineers.

Iowa has become the number one state in America in egg production in the past several years. Consequently, large amounts of eggshells are generated as unused wastes. Eggshell is made almost entirely of calcium carbonate crystals. Due to the rich calcium in eggshells, it has the great potential to be used as a calcium-based stabilizer material. However, such benefits of eggshells have not been evaluated and practiced in Iowa yet. This study aims to assess the beneficial use of Iowa eggshells as bio-based cementitious materials in stabilizing Iowa subgrade soils. Eggshells were ground into eggshell powder (ESP) through a coffee grinder. The testing results indicated that ESP treatment could elevate the plasticity of soil as well as the strength. The optimum content of ESP is 8%, which can achieve up to 30% strength improvement. The outcomes of this study indicate that ESP could be used as a non-traditional additive for Iowa soil stabilization.

Unified soil classification system (USCS) identifies a problematic high-liquid-limit clay that contains montmorillonite minerals as fat clay. Fat clay exhibits excessive swelling when wet and shrinkage when dry. Such drastic fluctuation in behavior qualifies fat clay as the most notorious member of the problematic soil group. This study identified wood-based biochar as a potential additive to fat clay to improve its engineering behavior and investigated the changes in the mechanical properties of the resulting mixture. Biochar amount is varied by volume-based percentage, and the compression and strength behavior of the clay-biochar mixture is assessed using laboratory tests. Compaction tests showed that the maximum dry unit weight of fat clay decreased as the percentage of biochar amendment increased. Six percent biochar added to the fat clay increased the optimum moisture content. The optimum moisture content remained unchanged when the volume of biochar rose from 6% to 10%. Unconfined compression tests showed that the shear strength of the fat clay increased at least twofold as the percentage of biochar was increased. Compression tests showed that the compressibility of fat clay decreased as the biochar percentage increased. Overall, the results of this study elucidated biochar’s potential as a novel soil improvement additive.

This paper aims to investigate the mechanical behaviour of peat stabilised with glacial rock flour for foundation construction. Peat, a natural organic soil, presents challenges for construction due to its high compressibility and low bearing capacity. This is an especially acute problem in Scotland (UK) where 25% of the territory is covered by peat. Glacial rock flour, a fine-grained powder produced by the crushing of stone in the construction industry, has been identified as a potential stabiliser for peat. This study evaluates the effect of varying percentages of glacial rock flour on the mechanical properties of peat, considering the unconfined compression strength (UCS). The findings indicate a significant improvement in UCS₂₈ of the mixture with the addition of up to 15% rock flour. Hence, it is concluded that peat stabilisation with glacial rock flour can be an alternative, cost-effective, and sustainable solution to the typically used excavate-and-replace technique in peatlands in the UK.

Municipal solid waste (MSW) is typically composed of organic and inorganic constituents that can decompose and release substantial amounts of phosphate into the environment, while impoundments contain the same phosphate-contaminated leachate. Stormwater retention ponds, on the other hand, have high concentrations of phosphate resulting from surface runoff. Infiltration of these waste liquids into the subsurface can contaminate the groundwater which necessitates the use of engineered liners to prevent such conditions. Compacted clay and geosynthetic clay liners are commonly used liners in these waste containment systems, but availability of these materials in remote areas of developing countries is challenging. This study proposes using bentonite amended fly ash as a potential sustainable alternative liner. Fly ash is a locally available by-product of coal combustion at power plants, and use of this will prevent its disposal and utilize it as a useful resource material. Preliminary studies showed 80% fly ash and 20% bentonite mix proportion is optimal to provide required hydraulic conductivity. The present study reports laboratory testing to investigate phosphate retention at this optimal mix conditions. Batch tests are conducted using fly ash and bentonite to determine their removal potential under different phosphate concentrations. In addition, column experiments were conducted on optimal bentonite-amended fly ash to assess the hydraulic conductivity and phosphate retention potential. Overall, the test results showed that the optimized bentonite-amended fly ash will serve as an effective low permeable liner with efficient phosphate retention.

Post-consumer plastic water bottles are foremost source behind the adverse effects on animals and the ambient environment as majority of quantity are dumped without being recycled or reused owing to a lack of awareness or infrastructure. This study explored the possible reuse of such post-consumer plastic water bottles as an admixture for altering the soil subgrade properties. The extent of replacement and sizes of waste material are the key aspects for improving the geotechnical parameters. So, this study focused on investigating the impact of plastic waste content and size through standard compaction, California Bearing Ratio (soaked and unsoaked), expansion ratio, and resilient modulus on stabilized soil subgrade. The series of experiments were conducted by varying the plastic waste content with 0%, 0.2%, 0.4%, 0.8%, and 1% of dry soil and two different sizes of waste strips with aspect ratios 2 and 4. It was discovered that adding plastic waste noticeably improves the behavior of stabilized soil subgrade under extreme conditions. Among the various combinations, laboratory test result of mix with 0.4% plastic content and strips with width 5 mm and length 10 mm shows the significant improvement in strength properties. Thus, this research provides an important approach to use waste plastic bottles for the construction of subgrade in order to lessen harmful impact of waste plastic bottles on living organisms and environment.

Over the last 10 years, the southeastern region of the United States has been directly impacted by climate change through a greater frequency of more intense rainfall and hurricanes, and led to billions of dollars in damage to infrastructure. The study defines the specific impacts of climate change on a random selection of geotechnical infrastructure components (GIC) (embankments and retaining walls) in southeast Mississippi and determines adaptive climate solutions. During this study, statistics (hurricane records) were presented to expose the severity of the geotechnical infrastructure components damage and how climate change directly impacts GIC; direct assessments are proposed as a predictive measurement to mitigate damage costs. Determining the steps that could be taken to develop and better prepare for lasting issues that come with climate change is the primary purpose of the pre-assessments. With a detailed inventory of deterioration to the existing infrastructure prior to the return of severe storms, adaptive climate solutions can be explored on a case-by-case basis, allowing a more holistic approach than what is typically available during emergency response following a storm.

Shallow geothermal is a renewable green energy that can provide heating and cooling for buildings in a safe, non-emitting, and affordable way, thus reducing the dependence on natural gas. The ground source heat pump (GSHP), also known as a geothermal heat pump, is the most efficient technology to utilize shallow geothermal by transferring heat between the shallow ground and buildings. It primarily consists of borehole heat exchangers with a U-pipe installed inside a borehole where water is continuously circulated in a closed (supply-return) loop using a heat pump. A thermal response test (TRT) is performed to assess the performance of a borehole heat exchanger. A constant input heat (Q) is applied to the circulating water, and its temperature on the supply and return side of the closed loop is continuously measured. Conventional instrumentation (i.e., the thermocouples installed at the end of the supply and return pipes) and methods for analyzing TRT results (e.g., using the line source method) evaluate only the average thermal properties without considering any variations along the depth. Using distributed fiber optic sensors (DFOS) in TRT can provide continuous temperature measurement throughout the depth with a good spatial resolution. The temperature profile data can provide a complete understanding of the thermal mechanism, eventually leading to a better and more efficient design. This paper describes a field-scale installation, testing, and sensing of three 600-feet geothermal boreholes. DFOS were installed inside and outside the U-pipe to measure the circulating water and the nearby soil temperature. A Brillouin-based interrogator was used to monitor the temperature changes during TRT with an accuracy of 1°C and a spatial resolution of 1 m. The temperature profile data were analyzed to understand the thermal response and estimate the variation of thermal properties with depth. The study also shows that DFOS can be effectively deployed in a borehole heat exchanger to provide real-time and long-term monitoring capabilities resulting in a better-informed and more efficient design.

Ultra-lightweight foamed glass aggregate (UL-FGA or FGA) has been broadly used in the United States in geotechnical applications as a lightweight fill to raise grades over soft soils or near-sensitive structures. Produced from post-consumer recycled bottle glass, UL-FGA has a high porosity and a non-reactive elemental composition that may also make it an ideal candidate for use in stormwater infrastructure. Mechanical properties of the aggregate have been evaluated through geotechnical laboratory work, and case studies have confirmed the long-term performance; however, limited information is available regarding water flow and storage properties for use in stormwater applications. This study aimed to evaluate the hydraulic and environmental properties of UL-FGA through laboratory-scale physical models. The water storage capacity and infiltration properties as well as how these may change over multiple events, at different compaction levels, or in different engineered systems, were evaluated in addition to any possible impacts on water quality. Results indicated that FGA drains rapidly, has a high capacity for water storage, and has a minimal impact on effluent pH and electrical conductivity. Production and transport of fine particles and related geotextile compatibility should be investigated further in future research.

Transportation infrastructure systems such as pavements constructed near coastal areas suffer distress from sea level rise and hurricane storm surges due to the presence of weak subgrades of cohesionless geomaterials. Traditionally, ordinary Portland cement (OPC) is used to improve the subsoil properties and design a resilient foundation for coastal pavements. However, the production and use of OPCs are often associated with significant carbon dioxide emissions, which affects the long-term sustainability benefits of such applications. Recently, geopolymers (GPs) have gained major traction as an alternative sustainable construction material due to their ability to provide superior mechanical performance and lower carbon emissions than traditional stabilizers. Therefore, a research study was performed to evaluate the engineering properties of metakaolin-based GP as a stabilizer for cohesionless coastal soils. Laboratory studies, including unconfined compressive strength (UCS) test and repeated load triaxial (RLT) test on untreated, OPC-treated, and GP-treated soil specimens, were performed at different curing periods. Sustainability benefit assessments were performed using a unified framework considering the effects of embodied energy of production, environmental factors, and socioeconomic factors. UCS and RLT studies showed that 20% GP treatment was effective in significantly improving both strength and moduli values beyond three days of curing. Sustainability assessments indicated that the application of GP has comparable sustainability benefits as compared to OPC-treated soils. Overall, the application of GP was found to be an eco-friendly solution to enhance the properties of cohesionless geomaterials for the long-term serviceability of coastal pavement infrastructure.

The present study aims to investigate the influence of fly ash leachate (FL) on the hydraulic and mechanical behaviour of two Indian bentonites with discrete mineralogical and chemical compositions. The investigation revealed that both bentonites with different mineralogical and physical properties noticeably affected free swelling, Atterberg limits, swelling potential, swelling pressure, and hydraulic conductivity. However, a comparative assessment for both types of bentonites shows that swelling capability, liquid limit, cation exchange capacity, and the specific surface area experience a directly proportionate variation to the free swell (80% decline), liquid limit (74% decline), swelling potential (61% decline), and swelling pressure (59% decline) when permeated with FL. In addition, a rise in hydraulic conductivity (28 and 38 times rise at a void ratio of 1.1) was observed with leachate presence for both bentonites. The research findings would therefore prove constructive to engineers for deciding on bentonite types for liner application in landfills.

Distributed fiber optic sensing (DFOS) technology transforms a fiber optic cable into a temporally and spatially dense sensor. When connected to a DFOS interrogator, kilometers of fiber optic cable become capable of continuous spatial monitoring of in situ variables such as vibrational strain (via distributed acoustic sensing, DAS) and temperature (via distributed temperature sensing, DTS). The USACE, ERDC, CRREL is studying the application and performance of DFOS as a geotechnical engineering monitoring tool in cold regions. A field-testing program at a soil DAS test bed monitored the seasonal effect of below-freezing temperatures. Seismic source impacts were performed along the DAS array, and response to impact was quantified using signal-to-noise ratio (SNR) as a performance metric. The array was observed to perform similarly before and after a blizzard. Results from ongoing cold regions DAS research studies of fiber optic cable installations in pond ice and at CRREL’s permafrost tunnel in Fairbanks, Alaska, support findings that DAS arrays perform well in cold regions. The ice-installed cable was continuously monitored during a breakthrough failure event, and results indicated that the DAS array responded to crack formation prior to the breakthrough. A DTS array was installed to monitor underseepage and the efficacy of a cutoff wall in a cold region earth embankment dam due to changing permafrost conditions. The DTS installation demonstrated significant temperature variability in an area of known structural instability, while structurally sound portions of the dam exhibited more consistent temperatures. These DFOS studies indicate that technologies such as DAS and DTS are useful cold regions geotechnical monitoring tools to help localize and remotely monitor in situ changes along kilometers of fiber optic array.

Seasonal frost heave impacts critical infrastructure in northern regions and creates design challenges for engineers. Frost heave issues occur where there are simultaneously a frost susceptible soil, cold temperatures, and a ready supply of water. At more northern latitudes in permafrost zones, conditions exist where the vertical moisture flow could be limited by a frozen layer at depth. However, climate change effects could lead to alternative moisture availability over the life of a project. This paper will explore moisture availability conditions during two laboratory freezing experiments on a frost susceptible soil. Temperature profiles, heave, and water intake data are collected, as well as digital images. Results show frost heave quantity and rate are reduced when moisture access is limited. Instead of increasing in overall volume throughout the test due to both phase change and taking on additional pore water, the dominant outcome is rearrangement of moisture along the vertical profile. Results of the research will serve to inform cold regions engineers on frost heave issues within the context of changing ground conditions due to climate change.

Warming of the climate adversely impacts the permafrost by causing a degradation in the shear strength, especially in regions of discontinuous permafrost. This is triggered by an increase in the temperature of the permafrost resulting in an increase in the unfrozen water content and a weakening of underlying materials. Thus, infrastructure built in such regions will be prone to damage and failure. This study investigates the shear strength of fine-grained soils as a function of temperature. For this purpose, a temperature-controlled direct shear device was developed to conduct direct shear experiments at desired temperatures between −10°C and +4°C. The temperature-controlled direct shear device circulates chilled glycol within the device to prepare specimens with uniformly distributed ice contents at various vertical stresses. The results showed that shear strength decreased with an increase in temperature. This reduction in strength was also dependent on the vertical stress and shearing rate. At low temperatures, the samples were seen exhibiting dilative behavior, while contractive behavior was observed in the samples tested at temperatures greater than −2℃. Finally, the peak shear strength of the soil mass decreased with a decrease in the shearing rate.

Due to the recent rapid environmental changes, there are significant changes in frozen soils, permafrost, and seasonally frozen ground. The seasonal temperature fluctuation-induced freeze-thaw (F-T) cycles significantly influence geotechnical infrastructure and especially impact the pavement foundation due to deterioration of pavement quality and imposed slope instability. Recent studies have confirmed that the application of fiber-reinforced soil is successful in the desiccation and wetting-drying cycles related to clayey soil cracking. However, different types and content of fiber impacts on surface cracking phenomena of clayey soil under the freeze-thaw cycle behavior have not been studied. Therefore, this study focuses on the influence of different types of fibers (i.e., carbon, glass, and basalt) and fiber content (i.e., 0%, 0.05%, 0.1%, and 0.15%) on surface cracking under freeze-thaw cycles on clayey soils. Each freezing and thawing process is continued for 12 h and controlled at temperatures of −20°C and 20°C, respectively, and the whole experiment consisted of five freeze-thaw cycles. The 2D image processing techniques and water evaporation characteristics were utilized to capture the crack evolution and propagation under the freeze-thaw cycle process. Results show that with an increased dosage of any type of fiber for the freeze-thaw samples, the crack area, total crack length, fractal dimension, and average crack width decrease. Further results showed that based on selected fiber types, carbon had the best performances; this might be with respect to the smaller specific gravity-related higher number of fiber particles used for the treatment and its higher tensile strength. In terms of basalt and glass, the quantification results for cracks were fairly similar, while their specific gravity and tensile strength values also hold close resemblances.

Ground source heat pump (GSHP) system has been introduced as an alternative to conventional snow/ice removal systems. The system exchanges heat with the ground through soil-borehole or energy pile heat exchangers with vertical U-tubes. The performance of the heat exchangers depends on the thermal properties of the ground formation and borehole arrays. This study evaluates the design and construction process of a soil-borehole thermal heat exchanger system (SBTHES) installed in a clayey deposit at Arlington, Texas. Parameters, such as total demand heat flux, soil thermal conductivity, and borehole arrays, are involved in the design of SBTHES. In addition, a thermal response test is performed to determine the in situ thermal conductivity of the ground formation in the vicinity of a borehole heat exchanger, as well as the thermal resistance.

Thermal conductivity of soils is a critical soil property in geotechnics, which provides essential information about the soil’s ability to conduct heat transfer. Erroneous data can be responsible for the inefficient design of infrastructure systems which rely on heat transfer, such as buried cabling, piping, and geothermal systems. This study investigated the influence of variations in salinity concentrations and soil type on soil thermal conductivity, considering potential implications for areas with a high water table or flooding events, as well as offshore wind projects. A total of 23 experimental tests were performed, and resulting 36 thermal conductivity data points were recorded. The results indicate that the salinity concentration or type of soil on site can increase (silty clay) or decrease (sandy soil) soil thermal conductivity at varying moisture contents during testing, which could provide a more informed, economical design for buried infrastructure that relies on heat transfer through soils.

Containment barrier systems, such as vertical slurry walls and low-permeable liners in waste containment systems, are commonly used to prevent groundwater contamination. However, traditional low-permeable clays used in these barriers have limitations in effectively removing various contaminants, including phosphate, which is a contaminant of global concern. The overarching goal of this work is to create a novel chitosan-bentonite composite barrier for improving the performance of containment systems. Chitosan, a material derived by deacetylating chitin, is a promising barrier material due to its ability to adsorb various contaminants. The purpose of this study is to investigate incorporating chitosan into these barriers to enhance their contaminant adsorption capacity. Previous studies were performed on three chitosans with varying degree of deacetylation (DOD) and molecular weights (MW) and one type of bentonite. The current study presents results from batch tests on four additional chitosan materials and a different source of bentonite. These tests assessed their individual phosphate removal capabilities and were compared with earlier findings. The chitosans exhibited varying phosphate removal efficiencies based on DOD, MW, surface area, and source. The highest removal efficiency ranging from 20.9% to 85.6%, at different initial phosphate concentrations, was achieved by one of the chitosan variants. In contrast, bentonite achieved 15.3% to 41.6% removal at different phosphate concentrations. Results suggest a composite material of chitosan and bentonite in engineered barriers could significantly enhance phosphate removal, especially at lower concentrations (0.5 mg/l), compared to a simple bentonite-based barrier.

Heavy metal accumulation in soil is a widespread concern due to the rapid infiltration of high contaminant loads into the groundwater aquifers. Phytoremediation is a promising biosolution for the removal of such hazardous substances. This study is an attempt to compare the potential of different agronomic (Abelmoschus esculentus, Vigna unguiculata ssp. Sesquipedalis), aromatic (Mentha, Ocimum tenuiflorum), medicinal (Catharanthus roseus, Aloe vera) plants in phytoremediation. Pot experiments were carried out with soil artificially spiked with heavy metals and compared to the control soil samples. Results indicate phytotoxicity signs in the growth and yield characteristics of the plants in contaminated soil. The medicinal plants and Ocimum tenuiflorum outperformed the other plant species in terms of germination, survival, and biomass yield. The plants showed higher removal of Zn (45%) in comparison to Pb (35%) and Cd (33%). The inferences highlight the higher heavy metal phytoremediation potential of medicinal plants and basil over agronomic crops.

Soil-bentonite slurry trench cutoff walls have been used for over 50 years to control groundwater flow and contaminant transport. During the summer of 2016, a 200-m-long and 0.9-m-wide full-scale, instrumented soil-bentonite slurry trench cutoff wall was constructed to a depth of 6.2 to 7.1 m. Primary research goals for the wall included evaluation of (1) the anisotropic stresses in the backfill, (2) stress-dependency of the backfill hydraulic conductivity, and (3) the rate of consolidation. These phenomena are time dependent and affected by the construction and post construction movement, including excavation, backfilling, backfill consolidation, and long-term backfill secondary compression (creep). This paper presents the results of six years of monitoring of earth pressure cells and pore pressure sensors. After six years, effective stresses within the wall remain far below geostatic. The maximum stresses observed are transverse to the axis of the trench and attributed to lateral deformations (i.e., inward movement of the sidewalls). The lowest stresses observed are the vertical stresses, reflecting the impact of arching or side wall friction as the soft backfill moves downward within the trench. Longitudinal horizontal stresses are intermediate between the transverse horizontal stresses and vertical stresses. For the last five years, the principal phenomenon controlling changes in stress has been secondary compression (creep).

One of the major purposes of landfill final covers is to minimize the infiltration of precipitation into the underlying waste. Deployment of conventional clay covers, geosynthetic clay liner, evapotranspiration (ET) covers, etc., has mostly been in practice to achieve the purposes. However, they have their shortcomings in the full attainment of the goals. In recent years, engineered turf has been introduced for landfill closure as a precipitation barrier to enhance cover performance. However, the field demonstration of engineered turf cover as the infiltration barrier is very limited. Soil moisture being one of the performance indicators of landfill covers, the objective of this study was to investigate moisture distribution characteristics of three distinct prototype landfill final cover systems: ET cover, compacted clay cover, and engineered turf cover, under in a humid subtropical climatic region. All the test covers (3 m × 3 m) were constructed side by side and were instrumented with moisture sensors at shallow depth (0.3 m depth). Descriptive statistics and histograms were used to summarize the features of the moisture distribution. Gaussian distribution theorem was used to investigate the spread out of the moisture data. In addition, the original moisture data were transformed to the standard normal distribution for a consistent framework for investigating the moisture variability of different covers. The analysis showed that 95% of the data were clustered around 0.173 to 0.238 m³/m³ at 0.3 m depth of engineered turf cover. On the contrary, the other two covers’ soil had a similar wider spread out of moisture data ranging approximately from 0.041 to 0.34 m³/m³. Results obtained from this study indicated the efficiency of engineered turf cover as an effective barrier to precipitation.

The characterization of in situ spatial variability of soil moisture content (θ) is highly relevant for understanding the landfill’s water balance (WB) cover hydrological processes, better modeling the processes, and applying them to effective cover design and planning. Considerable in situ soil heterogeneities and uneven climatic events result in unanticipated yield in the cover performance. Hence, it becomes necessary to probabilistically characterize the θ in the field for enhanced reliability. This study used Gaussian distribution analysis to produce probability density functions (PDF) of soil moisture at variable depths (0.30 and 0.76 m) of a pilot-scale WB cover under a semi-humid climatic region. In addition, the kernel density estimate (KDE) was used to produce a smooth estimate of the PDFs to define the multimodality of soil moisture distribution. The dimensions of the WB cover were 12 m × 12 m and 1.2 m in depth. The cover was constructed with local fine-grained soil (CH). Moisture sensors were installed at 0.3 and 0.76 m for continuous measurement of θ. The data collected from the instrumentation were analyzed using the R program. Results indicated that the soil moisture distribution at 0.30 m is more spread out than at 0.76 m depth. Also, the soil at 0.30 m depth showed a relatively more degree of normality than the soil at 0.76 m. The statistical analyses indicated that the soil at 0.76 m depth was significantly negatively skewed (skewness = −1.87). The θ distribution at both depths showed multimodality. The KDE-generated PDFs showed a distinguishable probability difference compared to the Gaussian distribution, especially at 0.76 m depth. The performance of Gaussian distribution was greatly improved using the KDE, especially when the soil moisture PDF showed highly skewed features. The results also indicated the initial soil moisture content affects the overall distribution of θ under the field conditions.

Global warming and subsequent sea level rise will cause the intrusion of saltwater into freshwater aquifers, affecting the pore fluid composition of both saturated and unsaturated soils. The change in hydration force caused by the dissolution of a charged solute (e.g., natural seawater salt) in pore water can reduce the water potential and produce osmotic suction in a soil. Previous studies have indicated that the volume change properties of reconstituted clay soils are dependent on both clay mineralogy and the pore fluid chemistry. In this study, the effects of salt content on the volume change behavior of two types of clay, that is, a natural lean clay collected from a coastal site in Delaware and a commercially available kaolinite, were investigated. The goal of this study was to investigate the effects of salt content on the compressibility behavior of the two aforementioned clays by performing one-dimensional consolidation tests. In this study, the initial osmotic suction of the saturated soil samples was changed by mixing the soils with varying amounts of sodium chloride (NaCl), in order to yield different salt contents. Compressibility test results showed that the compression ratio decreased as the osmotic suction increased from 0 to 3 MPa at an electrical conductivity (EC) = 49,000 (μS/cm). Additionally, increasing the level of salinity of the pore fluid from EC = 49,000 (μS/cm) to the saturated NaCl solution salinity, that is, EC > 100,000 (μS/cm), increased the compression ratio. This observed behavior is discussed in accordance with the effect of pore fluid salinity on the clay soils’ physiochemical factors, in particular the van der Waals attractive forces that occur at the clay particle scale.

Soil thermal response is of great importance in thermally related geo-environmental practices such as contaminated soil thermal treatment and renewable energy storage systems. Despite previous studies showing natural convection influence on soil thermal response in hydrostatic conditions, less attention has been given to its effect in the presence of subsurface flow. Additionally, the few studies that considered this matter in their analyses explored that only in the presence of confined groundwater flow. Therefore, this study investigated the role of natural convection on soil thermal response in the presence of unconfined groundwater flow. A finite element model was developed in COMSOL Multiphysics to simulate hydro-thermal behavior of saturated soils. Results showed that, depending on the soil permeability and groundwater flow velocity, natural convection impact on soil thermal response can be significant. Moreover, results were interpreted using a non-dimensional number, known as mixed convection number, which considers the coupled effect of permeability and groundwater velocity. It was revealed that when mixed convection number increases, natural convection effect intensifies.

Enhancing energy efficiency for attaining net-zero homes is a crucial subject that is of great interest for advancing sustainability and addressing the issue of climate change. Almost 43% of the annual energy bill of a typical US household is known to be accounted for by heating and cooling expenses. While there have been significant works on insulating the superstructure of a home, limited research work has been performed on insulating the foundations and substructures. A research study was designed and performed to examine the role and efficacy of expanded polystyrene (EPS) geofoam in insulating a slab-on-grade foundation system, a common type of shallow foundation where the concrete slab rests directly on the ground below it. Small-scale laboratory tests were conducted on a soil box with an insulated superstructure above a slab-on-grade foundation prototype. The performance of different thicknesses and installation configurations of geofoam insulations was compared to a control section with insulated superstructure and bare slab. The tests were performed inside a temperature-controlled environmental chamber set at −18°C. Thermocouple probes were used to monitor temperature profiles within the test setup. The insulated test sections were found to have consistently warmer slab temperatures compared to the bare slab conditions, and significant variation in performance was observed between the tested configurations. The configuration with insulation around the slab perimeter showed the best performance with over 10°C warmer indoor temperatures observed compared to the control section. The test results clearly indicated that the application of geofoam has significant potential in reducing the heat transfer between the foundation and the soil/air interfaces and therefore could lower the energy losses from residential homes.

Frost heave of frost-susceptible soils in the active layer can produce uplift forces that can jack up pile foundations. One source of these uplift forces is the adfreeze stress that develops along the pile shaft. More accurate adfreeze stress values (both adfreeze shear strength and residual adfreeze stress) must be determined to properly consider them in pile design. This research utilized the direct shear test to characterize adfreeze stresses at frozen clay till and steel pile interface. The impacts of temperature, initial water content, and shear rate on adfreeze stresses were also evaluated. Both temperature and initial water content significantly affect adfreeze shear strength but have minimal impact on residual adfreeze stress. In contrast, the shear rate has a considerable impact on both. A wide range of adfreeze shear strength values were measured, ranging from 40 to 400 kPa, while residual adfreeze stresses are significantly lower, ranging from 15 to 60 kPa.

Oceanic erosion in arctic coastal areas experiences some of the highest erosion rates with an average rate ranging from 2 to 6 m/year and extreme events seeing as much as 20 m/event. The soils in these areas are characterized as having high soil-ice content and low densities due to the preexisting permafrost. Seasonal weathering cycles are not typically thought of as direct contributor to the high erosion rates in the arctic oceanic areas, but they can increase the amount of sediment susceptible to transport by erosion. With the increased susceptibility to erosion, it’s much easier for mechanical wave action or groundwater runoff to transport the soil. Due to the high erosion rates of arctic coastal soils, the number of freeze-thaw cycles they experience is relatively small before the sediment is transported away exposing new soil. This study sought to investigate the impact that soil density, moisture content, and freeze-thaw cycles have on its erodibility. To accomplish this, a low plasticity soil was prepared at three different density and moisture content combinations, exposed to 0, 1, 2, 3, 4, and 5 freeze-thaw cycles, then their erosivity was measured at frozen, thawing, and thawed states to determine how soil-ice particle interactions change the soils erosivity. It was concluded that soil moisture content plays the largest role in the degradation effects that the soil mass experiences. With larger amounts of available water in the samples, the expansion forces generated during the freezing stage result in more pronounced breakdown of the soil fabric.

Temperature fluctuations lead to the deterioration of concrete through phenomena like frost action and thermal stresses. As the concrete in bridge decks cracks and spalls, the steel reinforcement is exposed which leads to corrosion and further deterioration of the bridge deck. This research will investigate the use of a ground-source bridge deck deicing system to mitigate deterioration within concrete bridge decks. Ground-source bridge deck deicing systems extract heat from the Earth and transfer it into the concrete through a closed-loop system of heat exchanger pipes embedded in the ground and the concrete bridge deck. This paper outlines the design and construction of a physical geothermal bridge deck model constructed at Montana State University (MSU). Preliminary results from experiments in MSU’s Subzero Research Laboratory under generic Montana weather conditions suggest that the heating system can mitigate certain mechanisms of concrete deterioration.

In this study, an innovative fungal-mediated technique is proposed to mitigate the frost heave in unsaturated pavement foundation. A bio-safe fungal strain, Pleurotus ostreatus, was fed with wheat straw and developed fungal mycelium successfully. A finite element model was established to investigate the mitigation of frost heave in unsaturated soil when growing fungi on the surface of pavement embankment. The results show that fungi slightly reduce the water content in pavement under the low rainfall intensity, which renders pavement unsusceptible to the freezing climate. Using the frost heave in pavement without fungi as a baseline, the frost heave is reduced to 83.63% at the center and to 61.20% at the shoulder edge by the fungal-mediated technique.

Particle size distribution (PSD) is recognised among geotechnical engineers as an informative soil descriptor, and often used to predict geomechanical behaviours. However, the effectiveness of PSD to characterise frost action is debatable. Existing criteria for assessing frost susceptibility have relied on traditional PSD descriptors_, such as C_u, which depend on individual parameters (i.e., d₁₀, d₆₀) which explicitly neglect the effect of fines and gravel content. In turn, it has been reported that fines content is critical in the formation of ice lenses. Grading entropy is a method which accounts for all the information in the PSD. In this work, normalised entropy coordinates are used to review PSD-based frost susceptibility criteria and assess whether alternative PSD descriptors can more successfully characterise frost action susceptibility. The effect of PSD (via grading entropy coordinates) on the development of frost heave is investigated using existing experimental datasets. The findings in this work highlight significant variability in the PSD criteria, suggesting that PSD alone is not a reliable indicator. However, examining experimental datasets indicated a clear effect of PSD using grading entropy coordinates for understanding the development of frost heave.

This paper investigates the altered behaviour of frozen pile-soil interfaces with respect to rising temperature in permafrost regions, especially near melting states. A series of steel model piles, embedded in artificially frozen cohesionless soil, were subjected to both sustained pull-out forces and constant rates of displacement to observe the creep behaviour and acquire the load-deformation curves. The pile-soil temperature was increased from a lower limit of −10°C up to the point of melting to study load transfer and creep behaviour of the pile under different exposure temperatures. Significant reduction of pull-out capacity and accelerated creep behaviour were found to be the primary consequences of rising temperature.

Due to the increase in global average temperatures, seasonal ground deformation has become a crucial engineering aspect for the safe design of structures built on permafrost regions. The present study investigates frost heave and thaw settlement in a cold region through finite element modelling (FEM). The study focuses on the effect of sequential placement of laminae on reconstituted varved clay profiles under free convective flow due to temperature gradients followed by freezing and thawing processes. Two representative soils were chosen to simulate the two laminae of actual varved clays. To perform numerical modelling, the input for van Genuchten parameters, water contents, saturated permeability, index parameters, stiffness parameters, and shear strength parameters were determined through laboratory tests, and thermal properties were adopted from the literature. The soil freezing characteristic curves (SFCCs) were obtained using the corresponding soil water characteristic curves (SWCCs). The study shows that the two selected soils exhibit varying levels of deformation under similar temperature conditions. Furthermore, the sequential placement of the two soils to create a reconstituted varved clay profile also impacted the deformation.

Accurate predictions of freezing and thawing depths could help set up an accurate time for seasonal load restriction (SLR), a load limitation policy that transportation agencies apply to reduce road damages during spring-thaw seasons. Mechanistic or empirical models have been used to predict the freezing and thawing depths. However, these model-based approaches cannot efficiently utilize the rapidly increasing data. This study attempts to apply recurrent deep learning to develop a data-based approach for the prediction of freezing depth. For this purpose, one frequently used algorithm in multivariate time series predictions, that is, long short-term memory (LSTM), is employed considering its ability to preserve historical information and dependencies. An LSTM network was constructed and implemented using the Keras deep learning library in Python for multi-step predictions of freezing depth with weather information as input. This new data-driven approach was tested on available data from road weather information sites in Michigan. Based on the training and validations with different model parameters, the optimum LSTM architecture was obtained for the application. This study showed that the proposed method can obtain satisfactory results for multi-step ahead predictions of the freezing depth.

This study explores the application of a geothermal deicing system as an environmentally friendly and cost-effective method of reducing the dangers and hazards caused by frozen roadways during the winter season. The existing snow removal method of using chemical solutions and salts not only has significant environmental consequences but also degrades roadway surfaces. Concrete is also subject to freeze-thaw cycles, which can eventually lead to deterioration, and the life span of the concrete pavement can be shortened significantly. This study investigated the efficacy of a geothermal system that uses only geothermal energy to de-ice bridge decks. Two demo bridge decks were built with embedded heat exchanger tubes connected to geothermal boreholes. The experimental results showed that the shallow geothermal system helps heating and deicing the pavement’s surface. The temperature inside and on the surface of the demo bridge decks remained less fluctuated during the winter, which helped to reduce the risks associated with freeze-thaw cycles.

Freezing and thawing indices are practical for assessing and predicting climate change, energy balance, carbon exchange, surface and subsurface hydrology, moisture balance, and productivity. Using daily maximum and minimum temperature records as well as future projections for 2000–2100, freezing and thawing indices were calculated along the Hudson Bay Railway. We applied a linear regression method to analyze past trends in the freezing and thawing indices over time and project these trends over three representative concentrated pathways (RCPs). The results of this study show that the freezing index has decreased significantly since 2000 and is expected to continue to decrease in the future, while the thawing index shows an increasing trend. As altitude increases, freezing index decreases while thawing index increases. According to the results of calculating frost numbers, permafrost coverage in sporadic zones will decrease to less than 10% by 2100. In continuous permafrost regions, the permafrost is projected to become discontinuous by 2100.

The application of energy geotechnology and artificial ground freezing technique always encounters the frozen soil layer in the subsurface. In cold regions, accelerated climate change induces freeze-thaw cycles on earthen structures. It is essential to develop a constitutive model for thermo-hydro-mechanical (THM) behaviors of frozen soils to assess the stability and serviceability of geotechnical infrastructure in the frozen ground. This study developed a constitutive model to investigate the pore-scale granular interaction between soil grains and ice crystals in saturated partially frozen soils. The microscopic temperature-dependent distribution of the ice phase in the soil pore spaces was anticipated as pore-filling and load-bearing particles. It was found that not all the ice crystals were being loaded in the soil skeleton. This microscopic morphological distribution of the ice phase was found to be associated with the soil stress states, indicating the dependency of THM behaviors of frozen soils on stress state and temperature. The model was validated by existing experimental results and showed considerable accuracy in the prediction of undrained shearing behaviors of frozen soils under various temperature and confining conditions. It also revealed the process of the ice invasion in the pore spaces, affecting the stress state and yield surface. Furthermore, the model might also explain the soil degradation due to freeze-thaw cycles by considering the variation in the effective granular void ratio, as reflected by the soil freezing characteristic curves. This study provides insight into the pore-scale mechanistic soil-water-ice interactions for frozen soils. The proposed model is compatible with the critical state framework and could be applied to geomaterials’ characterization in cold regions.

Organic soils in permafrost regions pose a significant challenge for engineers and planners due to their high compressibility and time-dependent settlement properties. This study characterizes the thaw-settlement behavior of highly organic soils using laboratory and field data from Canadian permafrost regions. The study compares the index properties of these soils with mineral soils and discusses the application of various easily determined index properties to predict the parameters that characterize the thaw settlement of peat samples. Water content was identified as the most reliable predictor of the compression index and thawed void ratio, which are critical parameters in calculating settlement. We illustrate how these models can be used to calculate different components that contribute to the total settlement of peat, including initial thaw strain due to the presence of excess ice, primary consolidation, and secondary compression. The results will help planners and designers estimate anticipated settlement, design and plan more effectively for new developments under changing climate conditions, reduce maintenance costs, and improve safety and serviceability.