International Journal of Geomechanics

Pretensioned spun high-strength concrete (PHC) piles are increasingly used to improve highway foundations with large pile spacing and short pile length without splicing. In this paper, a series of field tests comprising cone penetration tests (CPTs), piling, and static pile load tests were performed to investigate the load transfer mechanism of such PHC piles, the load transfer mechanisms of which are different from that of long piles with splices used in structural foundations. The variation of axial strain along PHC piles was monitored during piling and load tests using fiber Bragg grating (FBG) sensing technology and conventional vibrating wire (VW) strain gauges. The results show the superiority of FBG sensing technology in terms of reliability of data and feasibility of measurement under fast changing axial strain. The experimental data also show significant variation in the shaft and tip resistance during piling and the pile-soil strength limit state of the load tests.

Mining-induced voids provide essential channels for heat and mass transfer in disturbed strata. A group of dynamic distribution models of voidage was proposed to investigate the heterogeneous distribution and dynamic change of longwall mining-induced voids in overlying strata of a coalbed. It indicated that the voidage distribution has an evident periodicity and heterogeneity due to the periodical and inconsistent fractured subsidence of each key stratum with different thicknesses, strengths, and loads. Disturbed by longwall mining, the degree of difficulty of development increases successively from the pores and from the bed-separation fissures to the fractured fissures. In the caved zone, the porosity distribution along the coalbed strike and dip always presents a U-type appearance. In the fractured zone, the distribution shape of the transverse voidage alters from a narrow inverted U-type to a wide M-type, but the longitudinal voidage distribution always presents as an M-type from the narrow to the wide with time. The voids successively open and then gradually close from deep to shallow strata, and along mining operations they advance direction and present an arch-type distribution called the void-rich arch. The peak voidage near the mining face periodically extends forward with the advance of the mining operations and is slightly higher than near the starting line. The models and results might be applied to guide coalbed methane extraction, water influx prevention, coal fire prevention and control, and so on.

Sensitivity analysis is conducted to investigate the effects of uncertainty in hydraulic conductivity and van Genuchten parameters on transient seepage. To this end, a random number generator is used to generate random values from probability distributions of each parameter. The generator is coupled with finite-element software that handles seepage analysis in porous media. The Monte Carlo simulation approach is adopted for stochastic seepage analyses. The suggested method is applied on a homogeneous dam made of clayey sand. Uncertainties in each parameter are considered individually in different cases for rapid drawdown and rapid fill conditions. The results show that a variation of hydraulic conductivity has significant effects on transient seepage, and it is suggested that it should be treated as a random variable. However, the effects of the van Genuchten parameters on seepage are found to be insignificant, such that they can be treated as deterministic variables.

Micropiles of small diameter have been used in practice to increase load capacities of existing foundations on soft soil, which may resist additional loads from the vertical expansion of structures. Load transfer from the existing foundation to the micropiles is an important mechanism to consider when designing an existing foundation underpinned by micropiles. However, this mechanism has not been well investigated or understood. This paper presents a numerical study on an existing foundation underpinned by micropiles using three-dimensional (3D) finite-difference software. Verification of the numerical model was first achieved by comparing the results of the numerical model to those obtained from the full-scale loading test. In this verification, the numerical model was used to simulate an existing footing initially constructed on a natural soil to support a structure and later subjected to additional loads under two different conditions. Under the first condition, micropiles were installed without connection with the existing foundation. The existing foundation was subjected to initial loads, and then the micropiles were connected to the existing foundation for additional loads. Under the second condition, the foundation was first subjected to initial loads. Micropiles were installed and then connected to the foundation for additional loads. These two conditions were investigated further in a parametric study to understand the behavior of micropiles in the underpinned foundation under additional loading, including the load transfer between the existing foundation and the micropiles. This parametric study revealed that the installation sequence of micropiles had obvious effects on the vertical displacement of the footing, the percent load on the micropile, and the skin friction along the micropile. This study also revealed that the initial pressure ratio for underpinning and the length of micropiles had more effects on the behavior of the existing foundation underpinned by micropiles than the modulus of micropiles.

It is assumed that a deep spherical cavity is subjected to in situ stress at infinity, and the excavation process of the deep spherical cavity is treated like the decrease of pressure applied on its internal boundary. Trigonometric functions and hyperbolic cosine and sine functions are used in the scalar curvature. A non-Euclidean dynamic kinematic equation based on the strain incompatibility condition is derived. Laplace transformation and residue theory are used to deduce the stress fields. The strength criterion of the deep rock masses is applied to determine the number and magnitude of fractured zones and nonfractured zones of the surrounding rock masses around a deep spherical cavity.

Use of stone columns in soft soil reduces the excessive settlement and improves the bearing capacity with the additional advantage of providing a drainage path, which accelerates the rate of consolidation of the soil. Because of stone column installation in soft soil, surrounding soil properties are altered in such a manner that permeability and compressibility of the soil in the smear zone reduces and increases toward the drain, respectively. In the present paper, the effect of variable permeability and shear strength or compressibility in the smear zone due to stone column installation on the rate of consolidation of the stone column–improved ground was studied. The equal strain approach was considered in the analysis. The following three possible variation patterns of horizontal permeability and volume compressibility within the disturbed zone were considered: (1) reduced constant permeability with reduced constant compressibility, (2) linear variation of permeability with linear variation of compressibility, and (3) parabolic variation of permeability with parabolic variation of compressibility. The degree of consolidation computed by considering parabolic distribution of permeability and compressibility in the smear zone gives close prediction with field observation. Reduction of permeability in the smear zone increases the time requirement to achieve a particular degree of consolidation, and reduction of shear strength further increases the required time in the range of 5–21%. Degree of consolidation is significantly influenced due to strength reduction in the smear zone for lower diameter ratio, higher extent of smear zone, and lower stress concentration ratio.

Ground settlements above a tunnel as a result of tunnel construction can be predicted with the help of input variables that have direct physical significance. Several empirical and artificial intelligence methods for estimating ground settlements have been established by researchers. However, these methods have some limitations because the large number of influential factors involved makes tunnel–ground interaction complicated. In this work, a random forest (RF) was developed and employed to predict ground settlements above tunnels. To achieve this goal, tunnel geometry, geological properties, and construction parameters were investigated as input variables to utilize in the RF modeling, resulting in the maximum surface settlement value (S_max) and trough width (i) as the ground surface settlement index. To demonstrate the applicability of the RF model, two data sets associated with different features, which were obtained from a detailed investigation of different tunnel projects published in literature, were utilized for model development and were applied to check the performance capacity of the developed model. A fivefold cross-validation procedure was then applied to identify the optimal parameter values during modeling, and an external testing set was employed to validate the prediction performance of the model. Two performance measures, R² and RMS error, were employed. The relative importance of different parameters in the prediction of ground settlements was also investigated. Findings demonstrate that the RF method provides promising results and offers an alternative means in predicting ground settlements induced by tunneling.

The load deformation of ballasted rail tracks subjected to cyclic loading is investigated experimentally using a large-scale track process simulation apparatus and numerically through a combined discrete element–finite-difference approach. Laboratory tests were performed to examine the deformation and degradation of ballast subjected to cyclic loading at 15 Hz and a lateral confinement of $10 \mathrm{k}\mathrm{P}\mathrm{a}$. The laboratory results reveal that ballast undergoes significant deformation during the initial load cycles, followed by gradually increasing deformation attaining a steady value toward the end of testing. A numerical model based on a combined discrete element method (DEM) and finite-difference method (FDM) is introduced to study the load-deformation response of the ballast assembly while considering interaction between the ballast aggregates and the subgrade layer. In this coupled model, the discrete ballast grains are modeled by DEM, and the subgrade domain is modeled as a continuum by FDM. Interface elements are introduced to transmit the interacting forces and displacements between adjoining material domains in which the DEM transfers contact forces to the FDM, and then the FDM updates the displacements, which provides subsequent input into the DEM. This computational cycle continues with the increasing number of loading cycles. The numerical model is validated by comparing the predicted cyclic load-deformation response with the laboratory measurements. Contact force distributions and stress contours in the assembly are analyzed and presented graphically to interpret the behavior of the model track, and the effects that subgrade stiffness have on the axial strain and bond breakage of the ballast are investigated. This combined DEM-FDM analysis is also used to analyze the load deformation of an instrumented track in the town of Singleton, Australia, and the numerical predictions are compared with the field data.

First, this paper develops a new analytical model for the consolidation of stone column–reinforced ground by introducing multiple stone columns into the unit cell for analysis. Governing equations and analytical solutions are obtained for a time-varying surcharge loading, which includes four special loading schemes. The analytical model is then discussed and compared with a conventional analytical model with a single stone column in the unit cell. The results show that the conventional analytical model is a special case of the present model because they predict almost the same average degree of consolidation. This verifies the correctness of the proposed analytical model. Compared with the conventional analytical model, an apparent advantage of this analytical model is that multiple stone columns are introduced into the new unit cell, which makes it possible to extend it to solve the consolidation of a combined composite ground stabilized by impervious piles along with vertical drains with some modifications on the boundary conditions. In this context, analytical model and corresponding analytical solutions are further obtained for the consolidation of the combined composite ground based on the previously mentioned model. The new model is then applied to a field case study at the Huai-Yan Highway in Jiangsu Province, China, in which the embankment was stabilized with impervious piles in combination with prefabricated vertical drains. Good agreement can be observed between the predicted and measured settlement. Finally, a parametrical analysis is performed to investigate the consolidation behavior of the combined composite ground.

A rigid nonyielding retaining structure needs to be dimensioned to have adequate stiffness, such that it can resist mobilized lateral earth pressures. This corresponds to the at-rest condition, as there are, in general, negligible lateral deformations in the backfill. Measures that can mobilize higher soil shear strength and reduce lateral thrust are therefore sought to provide a more efficient design. The present study investigates the possibility of inserting compressible geofoam panels against rigid walls using physical model testing. Controlled yielding is allowed in the backfill with the occurrence of deformations in the geofoam. The mobilized earth pressures vary from the maximum at rest, to the intermediate, and finally to the minimum full active state depending on the magnitude of displacement. The effects of geofoam thickness and stiffness on lateral earth pressure reduction are explored. The measured pressure and displacement distributions form a comprehensive reference for use in calibrating design methods. Two analytical solutions are presented and compared with experimental data to evaluate their ability to calculate displacement-dependent lateral earth pressures.

This study presents a hydromechanical model, finite-discrete element method with fluid flow in three dimensions (FDEM-flow3D), that can simulate three-dimensional hydraulic fracturing of jointed rock mass with complex fracture networks. By taking full advantage of a unique topological connection between joint elements and solid elements in three-dimensional combined finite-discrete element method (FEMDEM) together with the cubic law, the authors built a three-dimensional fluid flow model. In addition, a connectivity search algorithm for arbitrarily complex three-dimensional fracture networks is proposed, which can be used to search the connectivity of arbitrarily complex three-dimensional fracture networks. Combining the connectivity search algorithm and the mechanical calculations of three-dimensional FEMDEM, the authors built the three-dimensional hydromechanical coupling model FDEM-flow3D, which directly implements hydromechanical coupling and can simulate fluid-driven fracturing in rock with arbitrarily complex three-dimensional fracture networks. Finally, the authors give five examples to validate FDEM-flow3D in dealing with the problems of steady flow, unsteady flow, hydromechanical coupling, connectivity search of discrete fracture networks, and hydraulic fracturing. The simulation results agree well with the theoretical or experimental results. The model provides a powerful tool for simulation of hydraulic fracturing in shale gas exploitation and geothermal extraction.

Sampling bias and class imbalance are important parts of model uncertainty that have a significant impact on the predictive probability of classification models. This study analyzed the influences of sampling bias and class imbalance on the performance of four common methods used in 10 models for seismic liquefaction—Bayesian network (BN), artificial neural network (ANN), logistic regression (LR), and support vector machine (SVM)—using controlled experiments based on penetration test (SPT) data from 350 standard case histories. The data are divided into two data sets with class distributions of 150:150 and 200:100, which are separately stratified and sampled to obtain 11 different cases of distributions (10:90, 20:80, 25:75, 33:67, 40:60, 50:50, 60:40, 67:33, 75:25, 80:20, and 90:10) to quantify the predictive performance of the four models using statistical model validation metrics, such as overall accuracy, area under the receiver operating characteristic curve, precision, recall, and F-score. The experiments show that the best distribution of liquefaction samples for training is not a fixed point but, rather, a range. The authors suggest that the best range of sample distribution is from 1 to 1.5 (liquefaction/nonliquefaction) for the BN method, from 0.67 to 1 for the ANN method, approximately 0.5 for the LR model, and from 0.5 to 1 for the SVM method. Furthermore, oversampling technology was used to try to improve the predictive capability of the four models for two samples (10:90 and 90:10) with bad class imbalance and sampling bias. The predictive performance of the oversampled sample considerably improved over the original samples with bad class imbalance and sampling bias for the LR model and the SVM polynomial (SVM-Pol) model rather than for the BN maximum likelihood estimation (BN-MLE) model and the ANN radial basis function (ANN-RBF) model. In addition, in the fields with unknown real distribution of classes in the population, when a training sample contains severe class imbalance or sampling bias, the authors recommend that researchers choose an oversampled sample that has the same class distribution as the population of the collected data to ensure optimal performance.

The fault fracture zone is vital to the stability of the surrounding rock of tunnels in geological engineering. In this study, a three-dimensional numerical model was established for Wuzhuling Tunnel of Zhuji-Yongjia Highway in Zhejiang Province, China. The dynamic processes of tunnel excavation were simulated through the fault fracture zone. The deforming performance and stress distribution of surrounding rock were investigated. Moreover, the stability of surrounding rock in tunnels was analyzed with consideration of the slope angle and the width of the fault. The simulation results indicate that the fault fracture zone in the tunnel can reduce the stability of surrounding rock. The slope angle and the width of the fault all have obvious influences on the stability of surrounding rock in tunnels. Furthermore, the collapse processes of a tunnel in the construction steps were investigated in a laboratory model. Reasonable agreements can be obtained to validate the model presented here and the simulation results. When excavating tunnels in a fault fracture zone, numerical analysis can be performed to find the dangerous area at which collapse might occur easily. This study can provide useful information on a supporting structure to prevent collapse disaster when designing a tunnel.

Numerical modelers are often faced with the challenge to numerically reproduce the physical behavior of soil–geosynthetic interaction problems using assumed values for missing soil and interface model parameters. This paper examines two such examples using the finite-difference method, (1) horizontal pullout of a geosynthetic (geogrid) reinforcement layer in a pullout box and (2) a geosynthetic (geotextile)-reinforced soil layer over a void. It also presents the results of parametric sensitivity analyses for the missing soil and interface model parameter values and identifies the values that give the best agreement with measured data. The paper further demonstrates that correct modeling of geometrical nonlinearity is key to accurately predicting the performance of geosynthetic-reinforced soil systems controlled by the tensioned membrane effect. The lessons learned in this study will be of interest to numerical modelers during numerical model design of geosynthetic-reinforced soil systems.

Control of surrounding rocks is one of the major problems in deep underground engineering under complicated conditions, such as high stress and tectonic fracture zones. This study proposed a three-dimensional confined concrete support system (CCSS) and investigated its main component: the confined concrete (CC) arch. The authors derived an internal force calculation formula for a circular arch with any number of sections and studied the effects of load, lateral pressure coefficient, node rigidity ratio, and other factors on the internal force distribution. In the analysis of CC part strength, damage first occurred to the CC159 × 10-C40 arch on both sides of the right and the left casings at an ultimate bearing capacity of 2,210 kN. To verify the correctness of the theoretical calculation and investigate the mechanical properties and damage mechanism of the arch, a full-scale indoor test on the CC159 × 10-C40 arch was conducted, and a 1:1 large-scale test system was developed. The authors found that the arch ultimate bearing capacity under the same load was 2,003.2 kN, a difference of only 9.36% compared with the theoretical calculation. The arch damage mechanism and key damaged parts were found to be consistent with the predictions of the theoretical calculations. The results of this research provide evidence for the design and analysis of CC arches.

For this study, a scaled model test is conducted to investigate the deflection of a laterally loaded pile and soil deformation in loose sand. An optical experimental setup is developed to capture images of soil movement and the readings of strain gauges along the pile. The deflection of the pile, derived from readings of the strain gauges, increases with the increasing lateral loads. Additionally, the displacement fields of ground surface and profile from a series of images are calculated using the particle image velocimetry (PIV) technique. This technique provides a more accurate estimate of the pile deflection compared with the double integration (DI) method. The images illustrate that the sand rotated in a position approximately 160 mm deep, which is identical to the results of the DI method. Finite-element analysis is used to simulate the model test, which verifies the accuracy of the PIV technique. The results demonstrate that the PIV technique and this optical setup are suitable for solving soil–pile interaction problems.

This study employed the detached eddy simulation (DES) numerical model to investigate the pier streamlining effect on dynamic turbulence intensity around bridge piers and the implication of such an effect on bridge local scour potential from a geomechanical perspective. A total of four test cases with piers having sequentially increased streamlining features were simulated. Comparison of the simulation results revealed that streamlined pier helped to reduce both the number and intensity of coherent vortices upstream of the pier. In addition, quadrant analysis of flow velocity in the horseshoe region showed that pier streamlining weakened the sweep and ejection events, the primary cause of sediment entrainment. The maximum bed shear stress gradually decreased as the pier streamlining extent increased. Findings from this study suggest that pier streamlining can serve as a scour countermeasure alternative; the numerical results also suggest that traditional excess shear stress theory on scour is at least incomplete; other factors, such as pressure fluctuation, momentum exchange between external and pore flow, and additional soil properties, should be taken into account.

Supported by available experimental and numerical findings on the behavior of geosynthetic-reinforced soil (GRS) retaining walls under working stress conditions, an analytical method was proposed to quantify the toe restraint of vertical GRS retaining walls. The lateral earth pressure on the facing is calculated by Coulomb’s theory of active earth pressure, and a polygonal distribution is used to quantify the horizontal connection loads of the reinforcement layers. The toe restraint is quantified through force and moment equilibriums of the facing column. The analytical toe restraint was then incorporated into an analytical method for reinforcement loads of vertical reinforced soil masses. The proposed approach was validated against the results from full-scale and large-scale tests. The approach can be used to compute the reinforcement loads of GRS retaining walls under working stress conditions and with active earth pressure on the facing so that the serviceability of GRS retaining walls can be better analyzed in practice.

Utilization of fly ash as a suitable and economic alternative to natural soil for construction of embankments is becoming common, particularly in countries such as India, where thermal power plants are still a major source of power. However, while using this material in a seismic zone, its dynamic properties may play a crucial role during an earthquake event. Of particular concern is the vulnerability of the material to liquefaction-induced failure, because pond ash mainly consists of noncohesive fine sand and silt. The present work focuses on dynamic response analysis of a 52-m-high pond ash embankment situated in Renusagar, northern India, using a fully coupled nonlinear finite-element analysis. Constitutive material models of the pond ash material were calibrated using cyclic triaxial experiment data performed on pond ash samples collected from the aforementioned embankment. A significant amplification in the acceleration response was observed between the base and crest of the embankment ranging from 1.43 to 4.2 (mean, 2.9). The mean amplification profile is consistent with the observation from the literature. A large amplification in the horizontal as well as vertical displacement is also observed with values up to 17.3 and 45 cm, respectively. The pond ash embankment is found to be susceptible to liquefaction for the majority of the earthquake motions considered in the study.

Most shallow foundations are built in unsaturated soils above the groundwater table. Being able to evaluate the bearing capacity of these foundations is important in foundation design because the conventional bearing-capacity equations, which were developed for soils in saturated or dry states, are not directly applicable. This paper presents an effective stress-based finite-element formulation and shows how it can be used to compute the bearing capacities of shallow foundations in unsaturated soils. The mechanical behavior of unsaturated soil is described using the elastic–perfectly plastic Mohr-Coulomb model. It is shown that suction and hydraulic hysteresis directly impact the bearing capacity of unsaturated soil foundations. The effects of three different drainage conditions are also investigated, namely, a constant suction, a constant moisture content, and a constant contribution of suction to the effective stress and strength condition (also referred to as a constant $\chi s$ condition). It is shown that the constant $\chi s$ condition provides a good approximation to the other two and may simplify calculation of bearing capacity. When foundation loading occurs quickly, meaning a condition of constant moisture content prevails, a constant $\chi s$ condition can be assumed without loss of significant accuracy. The $\chi s$ magnitude can be taken as being equal to the initial in situ value.

A discrete-element method (DEM)–based numerical model was developed to simulate the triaxial compression response of sand strengthened using microbially induced carbonate precipitation (MICP). A three-dimensional (3D) sphere packing algorithm that uses a particle-growth model was used to generate the initial assemblage of particles. A parameter identification approach was used to evaluate the five microscale parameters of the DEM model (two elastic and three rupture parameters) using experimental results from drained triaxial compression tests on sand. The interparticle friction angle was found to be the most influential of the five parameters with respect to modeling the constitutive response. A particle homogenization approach was used to model the particles when they are strengthened with low amounts of calcium carbonate (<1% by mass). The particle contacts are assigned a cohesive shear strength when higher amounts of calcium carbonate (≥1% by mass) are present to model the effect of cementation between sand grains. This DEM model was shown to be capable of adequately simulating the drained triaxial compressive response of MICP-strengthened sands. The increase in microstructural heterogeneity as the carbonate content is increased was visualized through normal contact force distributions. The model can be used to estimate the desired level of cementation for the design of MICP treatment strategies with minimal experimentation.

Geocell reinforcement has found a large applicability in the area of pavement engineering, and its deformation characteristics play an important role in the analysis and design of pavements. In the present work, a simple analytical approach that idealizes geocell reinforcement as a beam subjected to vertical symmetrical loads and foundation soil as nonlinear Winkler springs are proposed. A detailed parametric study indicated the influence of the weight of infill material, applied loads, the modulus of subgrade reaction, flexural rigidity of reinforcement, interface resistance, and the ultimate bearing resistance of foundation soil on deformation characteristics of reinforcement. Charts that are useful in the analysis and design of pavements reinforced with geocell are presented.

This paper intends to study the dispersive nature of shear waves transmitting in an inhomogeneous viscoelastic layer embedded over a prestressed orthotropic substrate. The frequency equations obtained under the combined effect of viscoelasticity and inhomogeneity were analyzed. It has been observed that the phase velocity of the shear wave is influenced by the prestress present in the half-space. The method of separation of variables has been incorporated to deduce the dispersion equation of the shear wave. Consequently, it has been found that the dispersion equations from the real and damped parts converged with the classical Love wave equation under certain suitable conditions. The graphical representations show that inhomogeneity, viscoelasticity, prestress, and shear moduli had a remarkable effect on the phase velocity of the shear wave.

Because of the lack of adequate monitoring performance data for shield tunnel segments from either laboratory testing or in situ measurement, it is difficult to improve the current segment design codes. As a result, overdesign or excessive use of reinforcement in tunnel linings is common. To overcome these segment design inadequacies, this study aimed to investigate the bending behavior of RC members based on measured strain data and the modeling results from a proposed analytical model, which takes into account section nonlinearity resulting from concrete tensile cracking and the actual effective moment of inertia. The cyclic four-point loading test was performed on a RC beam with an embedded optical fiber sensor and on a smart tunnel lining segment, in which two vibrating wire strain gauges with thermistors were welded into a rebar cage on either side of the neutral axis. The measured strain data for the rectangular beam subject to concrete curing and subsequent four-point loading justify the applicability of the optical fiber sensor. The results of the load–moment relationship obtained from the model were found to be in good agreement with the theoretical solution, verifying the correctness of the proposed analytical model. This model has been proposed to predict the bending behavior of the smart tunnel lining segment. The modeled load–deformation relationship matched reasonably well with the measured strain data, except for the modeled results of tensile strain after cracking. This discrepancy may have been caused by either the influence of the concrete tensile cracking on the local bonding condition at the concrete–sensor interface or the modeling difference of concrete tensile behavior. Despite the discrepancy between the modeling results and the measured strain data after cracking, the statistical parameters justify the application of the proposed analytical model to RC segment design and to the design of recently developed composite segments.

In this study, cyclic triaxial tests under isotropic and anisotropic stress consolidation conditions were performed on Nuozhadu granular soil, and a constitutive model based on the Bouc–Wen model and endochronic theory was applied to investigate the dynamic stress–strain relationship and pore-water pressure of granular soils under cyclic triaxial stress states. In the isotropic stress consolidation condition, dynamic stress degradation occurred as a result of increased pore-water pressure and the reduction of effective stress. This paper presents the general validity of the model and its ability to describe several features of granular soil, including soil cyclic mobility, plastic strain accumulation, and stiffness and strength changes resulting from cyclic loading. Then, the equation of the model and key model parameters related to soil behavior, such as hysteresis and contractive and dilative behaviors, are further discussed. The proposed model was used to simulate the dynamic stress–strain relationship, effective stress path, and increased pore-water pressure under undrained conditions. The numerical results were found to have good agreement with the experimental curves.

The estimation of the undrained pullout capacity of plate anchors is vital for the design of offshore floating facilities and has been an active topic of research for several years. Most of the previous studies have proposed empirical relationships to predict the undrained pullout capacities of inclined anchors. Generally, the buoyancy effect is added to the shearing resistance to obtain the total capacity, which is less than or equal to the maximum capacity. In this paper, an alternative mechanism-based simple design methodology is proposed to estimate the undrained pullout capacity of inclined anchors. A series of finite-element analyses are performed for a range of anchor inclinations in soils with uniform and heterogeneous shear strength. The effects of anchor embedment, soil unit weight, and anchor–soil interface tensile capacity are studied in a systematic manner. A relationship has been developed to estimate the depth at which the anchor undergoes a transition in the failure mechanism from shallow to deep failure mode. Robustness of the proposed methodology is also examined for a generalized shear strength profile of the soil. The proposed model estimates pullout capacity with the maximum error being less than 5% for any soil or anchor property.

In this study, an implicit finite-difference code for nonlinear consolidation and secondary compression was developed and implemented in a publicly available JavaScript Web application. The rate of secondary compression was defined based on the distance in e-log₁₀(${\sigma }_v^{\prime }$) space between a current point and a corresponding point on a reference secondary compression line (RSCL). Modeling secondary compression in this manner enables simultaneous occurrence of primary consolidation and secondary compression. The finite-difference code was first verified by comparison with three benchmarks. The influence of secondary compression on settlement versus time was then studied and found to be important for thick and/or low-permeability layers for which primary consolidation requires significant time. Overconsolidated soil was observed to result in an apparent increase in C_α with time, which was also observed in experimental data. Finally, secondary compression was found to be capable of generating excess pore pressure in soils with impeded drainage boundaries.

In this paper, a novel meshless numerical method known as general particle dynamics (GPD) is developed to reveal the mechanism of the rock fragmentation using tunnel-boring machine (TBM) cutters. Rock fragmentation by one cutter and by two cutters is investigated using GPD. The numerical results obtained from GPD well agree with the previous experimental and numerical results. Moreover, the effects of arrays of flaws on rock fragmentation are also studied using GPD as well as stress fields and rock fragmentation efficiency. It is found from the numerical results that arrays of flaws significantly influence the drivage efficiency of rock fragmentation as well as the depth of chipping and the coalescence modes of flaws.

The efficacy of phenol transport from the aqueous phase to peat soil for assessment of the attenuation capacity for migratory phenol in subsurface water pollution was investigated by the application of multiple linear regression (MLR) and artificial neural network (ANN) models. The batch kinetics study was performed, which revealed that the Freundlich isotherm model fits reasonably well with experimental results. A maximum value of 43% phenol removal efficiency was achieved in 200 g/L of soil, an initial concentration of phenol of 10 mg/L, and an equilibration time of 6 h. A sum total of 270 laboratory batch adsorption tests were conducted, and the results were applied in MLR and ANN models. Some of the influencing factors, such as pH, initial concentration, mass of soil, contact time, and so forth, on removal of sorbate by peat were also investigated in the present research. The experimental results exhibit a reasonable goodness of fit [higher coefficient of determination, R², and lower root-mean-square error (RMSE), and mean absolute performance error (MAPE)] of the previous models.

To efficiently control postconstruction settlement (PCS) of a high-speed railway embankment on sand over soft clay, a study was conducted to analyze the performance of the embankment foundation treated by one of two methods; that is, only the clay was treated by jet grouting pile (JP foundation), or only the sand was treated by dynamic compaction (DC foundation). Two-dimensional coupled mechanical and hydraulic analysis was conducted using the finite-element method, and the measured and simulated results were compared. This study analyzed mainly performance of the JP foundation involving settlement during construction, PCS, and the soil arching effect related to differential settlement between the pile and soil, vertical effective stress, and the overall efficiency coefficient. Settlement of the DC foundation is also discussed. The results show that during construction, sand of the JP foundation produced a large settlement but became stable under loading of the embankment fill. Settlement of the DC foundation during early construction was reduced significantly compared with that of the JP foundation, but deep sand and clay still produced a large settlement. PCS of the JP foundation was controlled effectively, whereas PCS of the DC foundation was controlled almost completely ineffectively. The soil arching effect took place in the JP foundation because of the differential settlement between piles and soil, the major portion of the additional effective stress was supported by the piles, and the overall efficiency coefficients reached 0.5 at the end of construction and 0.74 at the end of consolidation.

A key challenge for estimating seismic response of piles and soils in liquefied and laterally spreading ground is the efficient prediction of local loosening phenomenon (shear localization) at the interlayer between the liquefied loose sand and the overburden crust. To this end, a simplified finite-element (FE) model was developed. In the soil model, a soft interlayer element with a thickness and corresponding low reference shear modulus was developed to represent the shear localization phenomenon. The proposed FE models were then used to simulate centrifuge tests of a single pile, a two-pile group, and a six-pile group in sloping liquefiable profiles that lead to lateral spreading. Predicted results of the shear-localization-induced soil lateral spreading displacement, as well as the structural response, agree reasonably well with the test records, indicating that the proposed FE model is capable of approximating the seismic responses of soil and piles in liquefied and laterally spreading ground. In addition, a parametric analysis was performed to build a relationship between the thickness and the low reference shear modulus of the soft interlayer element.

Numerical methods that incorporate hydromechanical processes in unsaturated soils meet substantial challenges when considering semi-infinite zones. Although restricted assumptions can limit applicability, the analytical solutions can offer opportunities for appraising numerical procedures. Analytical solutions to a one-dimensional semi-infinite region were developed using a Fourier integral transformation that incorporates the coupling between infiltration and deformation in unsaturated soils. The results show that the dimensionless rainfall intensity has a significant effect on the coupling effect. As the desaturation coefficient increases, the coupling effect becomes stronger. An increase in the initial pore-water pressure causes faster movement of the pore-water pressure profile.

This study proposes a practical method for determining active earth pressure of confined cohesionless soil. A trapezoidal thrust wedge model confined by two vertical rigid retaining walls is developed to derive the governing equations of earth pressure distribution and the resultant force. The resultant force depends on the unknown incline angle of the sliding plane and must be maximized with respect to the angle. The active earth pressure can be determined once the incline angle is obtained by solving the governing equations with the finite-difference method. Based on these equations, parametric studies are conducted to investigate the effects of the confined width on the active earth pressure and the inclination of the sliding plane. As expected, the active earth pressure decreases with the confined width due to the arching effect. In contrast, the incline angle of the slip plane in the confined cohesionless soil is in close proximity to that of Coulomb’s solution. Moreover, the incline angle of the proposed solution and Coulomb’s solution are used to determine the active earth pressure, respectively. The results of the two solutions are almost equivalent. Based on these findings, a practical method is proposed, in which the incline angle of Coulomb’s solution is suggested for the derived equations to determine the active earth pressure of confined cohesionless soil. The proposed method provides satisfactory results when compared with previous studies.