Geo-China 2016: In Situ and Laboratory Test Methods for Site Characterization, Design, and Quality Control

There is very little information available in the literature directly related to the compaction of clay type materials in highway embankment construction during cold weather in seasonal frost areas, although every construction season some work is done during the winter on account of the short construction season normally available in seasonal frost areas. This paper addresses a case study of a low highway embankment fill (less than 3 m in height) constructed during freezing temperatures. This case study embraces compaction behaviour during winter, observations made during spring thaw, embankment remedial works following spring thaw, and the subsequent performance of this roadway.

In order to accurately analyze the reason of coal mine water inrush and study on coal mine hydrological condition, this paper takes coal mine water inrush as an aquifer dewatering test. Integrating hydrogeological drill, hydrogeological prospecting, hydrological monitoring system, etc. the paper provides an original groundwater seepage field recovery technique. And this technique was successfully applied to recover the original seepage field of the weathered Zhiluo Group roof aquifer of the 2^-2 coal seam of the south panel of Ningtiaota Coal Mine. Based on the water inrush data collected by the hydrogeological monitoring system, this paper did an inverse calculation of the parameters of the aquifer. The permeability coefficients calculated from pumping test are 2.13m/d and 2.15m/d, while the coefficient from inverse calculation is 6.88m/d. The influence radiuses calculated from pumping test are 106m and 89m, while the influence radius from inverse calculation is 1941m. The results shows that the hydrogeological parameters calculated from water inrush inverse calculation are apparently bigger and more accurate compared to the parameters calculated from pumping test.

Clarity and definiteness of the spatial distribution characteristics of continuous compaction measured values are the preconditions for the compaction uniformity evaluation. In this study, by applying the method of geostatistics and the exploratory spatial data analysis to the continuous compaction measured values in an test area within Loudi construction site of ShangHai-KunMing High-Speed Railway, the frequency distribution, the spatial autocorrelations and the anisotropy of continuous compaction measured values have been evaluated. The objective is to determine the spatial distribution characteristics of the continuous compaction measured values. The results show that continuous compaction measured values are close to the standard of normal distribution and the continuous compaction measured values have a positive spatial autocorrelation. The spatial variability and spatial autocorrelation of the continuous compaction measured values in the transverse direction of the subgrade are larger than those in the longitudinal direction of the subgrade. The spatial distribution characteristics of continuous compaction measured data of road subgrade are able to reflect the compacted state of road subgrade accurately. It is therefore a more accurate method for compaction uniformity evaluation and quality control and quality assurance.

This paper summarizes the study on stress distributions induced by light weight deflectometer (LWD) tests on typical road subgrade soil masses in Hong Kong and they were subsequently compared with the ones from mechanistic and finite element analyses. The key findings are as follows. The vertical stresses were observed to have a more rapid reduction within the upper region (400 mm approx.) of the soil mass along the centre-line under the applied load. An inflexion point exists of stress change occurs at a depth of approximately 400 mm (1.5 times load plate diameter). Beyond the inflexion point, the rates of deterioration in stresses were found to be considerably lower. Both MePaDs and SIGMA/W analyses showed similar findings. For example within the coarse subgrade material with the applied stress of 132 kPa (i.e. full drop-height), 81% and 90% of stress reductions were resulted from the MePaDs and SIGMA/W analyses respectively in the upper region and the actual measurements yieled about 78% of reduction. Along the centre line under the applied load, the horizontal confining stresses decreased dramatically within a very shallow region of the subgrade material. The measurements exhibited most of the confining stress deterioration occurred at the top 300 mm (1 times load plate diameter) whereas both MePaDs and SIGMA/W analyses showed a distnctive inflexion point of change in stresses, being located at approximately 250 mm and 150 mm respectively. Over 95% of the confining stresses diminished beyond the inflexion point and the levels of stress were observed to marginally increase near the bottom of the container. The LWD moduli yielded against the two classic stress ratios: (1) deviator stress / confining stress ratio, and, (2) bulk stress / deviator stress ratio followed similar patterns of the ones for resilient moduli obtained by RLT tests. This has formed important breakthroughs in explaining the ways which in-situ stresses induced by the LWD tests may cause alterations in ELWD as previously investigated by other researchers in this area.

Hereafter are the results of underground testing by the piles with the method of vertical static testing O-cell (Osterberg method) are presented, which had been made on Expo 2017 projects, buildings of Pavilion in Astana, Kazakhstan, in 2013. Experienced bored piles with a length of 31.5 m, diameter 1000 mm. Bi-directional static load tests carried out in accordance with ASTMD1143.The method proposed by George Osterberg, allows to simultaneously determining the estimated soil resistance under the lower end of piles and on its lateral surface. Feature of O-cell test is that the load is applied not on the pile head, and the body of the pile, where is a jack (power cell), which works in two directions. Power cell (O-cell) shares the experimental pile into two parts: upper (upper test item) and the bottom (lower test item). Hydraulic jack is installed at a depth of 2/3 the length of the piles-16.8 m. This O-cell test can obtain biggest bearing capacity of boring piles on difficult soil conditions.

Desirable soil properties can be obtained through densification of soil using compaction. To control the quality of compaction, the sand cone and nuclear density gauge (NDG) are commonly used to measure the in-situ dry density and moisture content of compacted soil. However, the sand cone test is destructive and time consuming while the NDG poses a health hazard because it uses radioactive emissions to measure the density and moisture content of compacted soil. The alternative safer option could be the electrical density gauge (EDG). This study evaluated the repeatability, accuracy and applicability of the EDG using a range of four sandy soils. First, two EDG readings were taken for each test spot, followed by the sand cone in the same location. EDG measurements were then compared to those of the sand cone and oven drying method for dry density and moisture content respectively. Results showed that EDG had good repeatability based on test-retest comparison of the paired values. EDG values for moisture content were consistent with those of the oven drying method. However, EDG measured dry density differed from the sand cone. It was recommended that the EDG be used for moisture content determination and that the density calibration relationship be revised to improve its accuracy.

In view of the traditional vacuum preloading, the vacuum pressure cannot transfer to the deep foundation, so the deep foundation reinforcement effect is poor. This paper presents a case study on the application of vacuum preloading on the deep dam foundation of the Huaihe River. In order to overcome the disadvantage of the traditional, it uses the pipeline system instead of sand cushion layer for horizontal drainage channel. And the vacuum pressure under membrane, ground settlement, and pore water pressure were monitored, and the change of moisture content and void ratio before and after reinforcement were analyzed. The test results show that the vacuum preloading is effective to improve the deep foundation.

In this paper, in order to compare the differences between open-ended boots pipe pile and closed boots pipe pile in sandy soil, a discrete element method is applied to investigate the foundation bearing capacity test based on the numerical simulation software PFC^2D, obtaining both the foundation bearing capacity, the scope of reinforcement in sand and the failure pattern under the load. The analysis has a certain guiding importance on optimization design, construction of pile foundation and cutting down the engineering costs. Additionally, it provides certain reference significance for an understanding of the failure mechanism of soil deeply.

The flood-control wall is a kind of structure widely used in Shanghai to prevent the overflow of river water. As the flood-control walls are usually used in wharves, the hitting of cargo ships often cause the damages of the wall. In this paper, the damage of a flood-control wall because of the sinking of the cargo ships is evaluated by back analysis of the displacement data of the wall measured in the field. Analytical and numerical methods are adopted to perform back analyses. From the results of back analyses, it is found that although the horizontal displacement is obvious, the bearing capacity of the flood-control wall can meet the requirements of the accidental load resulted from the sinking of the ship and it won’t fail.

The ground penetrating radar (referred to as GPR) is a method using the reflection of high frequency electromagnetic pulse wave to detect the subsurface conditions, which has the properties of high precision, convenient to perform, easy to use and nondestructive detection. In this paper, the GPR method is employed to detect the potential cracks in a flood-control wall, of which the surface cracks has been found on the top surface. From the results of the nondestructive method, it is found that obvious internal cracks do not exist in the flood-control wall and the integrity of the wall is still good enough to work normally.

Design of foundations can be performed using empirical Menard pressuremeter rules. Another trend of interpretation of these tests consists of identifying the rheological soil parameters using analytical or numerical methods. These parameters are then used to evaluate the bearing capacity and settlement of soil foundations using numerical software. This paper deals with the bearing capacity and settlement predictions of bored pile based on numerical interpretation of pressuremeter tests. A numerical program is developed to analyze these tests taking into account a non linear elastic model and an elastoplastic model based on the generalized elastoplastic Prager’s model with the Von-Mises. Numerical calculations using FLAC software, taking into account the rheological parameters derived from this approach are performed in order to predict the behavior of a single bored pile subjected to an axial vertical load. The predictions are compared to the measured data.

Reclamation lands have been widely evolving worldwide in the last decades especially in the Arabian Gulf where major reclamation fill projects were developed. This paper focuses on some projects that took place in United Arab Emirates (UAE) which is considered to be one of the leading Gulf countries in reclamation projects. Most of the reclamation projects in UAE were done in water depths ranging from a few meters up to 20 meters. The fill material composed mainly of shelly carbonate sand, with fine contents limited to 10%. Vibro compaction (VC) technique was used in most of the projects to improve the deep fill material and was combined with surface compaction of the top 1 to 2 m. In a recent project and after completion of deep and surface compaction, subsidence cases started to appear with different sizes that varied from minor surficial depressions up to sizable sinkholes with a depth up to 2.0 meters. This paper provides an overview of projects that were constructed in the same area using similar material and reclamation techniques. The paper attempts to identify possible causes that contribute to the formation of these depressions/holes.

Soil stabilization with cement is a common technique applied for improvement of the mechanical properties of natural soils. Consequently, the stiffness assessment of these materials, namely at small strain levels, has particular importance both for design and quality control purposes. One novel test method developed by this research team is EMM-ARM (elasticity modulus measurement through ambient response method), which is based on resonant frequency identification of a mould that contains the sample under testing. A new sampling technique aimed for in-situ application of EMM-ARM is presented and tested in this paper. This research further involved the use of piezoelectric transducers (bender-extender elements) for discrete measurement of shear modulus in laboratory tests using reconstituted samples of this stabilized material. All test results were analysed, compared and validated through reference tests based on unconfined cyclic compression testing with local strain measurement.

The stochastic and complicated pore characteristics have significant influence on engineering properties of unsaturated soil. Taking remolded red clay of Jiangxi province with different clay content as objects and taking complete soil-water characteristic fitting curves by using MATLAB software as carrier, the distribution of pores during dehydrated procedure is analyzed from micro-view of point. Based on previous achievements and large number of experimental results, the equivalent calculation method of pore radius for clay grain is proposed by using statistical theory. Taking indoor experimental results as the basis, the method of incremental step is presented and the algorithm are implemented in detail. By comparing the theoretical results of maximum capillary rise height with one-dimensional capillary experimental data, a good agreement is achieved, which is verified the proposed calculation method. As a result, the quantification of micro-structure is realized. Moreover, the proposed calculation method offers an effective method for calculating the maximum capillary rise height.

This paper is an attempt to study the influence of pore hydro-dynamics on consolidation characteristics of soft clays using two vertical geodrains viz. coir-jute fiber drain and sand drain of ‘n’ value 11.04. Objective is to analyise soil-structural changes due to effect of various physico-mechanical parameters on consolidation phenomena and its influence on degree of consolidation based on isochrones. A theoretical philosophy of pore water and pore behaviour on consolidation characteristics is presented and results are analyised using theoretical solution of consolidation based on isochrones developed by authors. Soil structural changes were determined using SEM and volumetric characterization was done with micro structure characterization (MIC) software based on ASTM method. Results justify the importance of pore hydrodynamics on rate of consolidation of soft clays and further giving a new concept of changing soil structure/orientation as per equilibrium of pore hydrodynamics for rapid compression.

To clarify the three-dimensional diffusion mechanism of grouting in fault, a test device with a large size was developed. Considering the interaction of multiple grouting, four times grouting tests were developed by using three sets of grouting pipes. During grouting process, the real-time injection pressure, injection rate, soil pressure, and seepage pressure were monitored. Moreover, three-dimensional diffusion form of slurry was exposed by excavation. Based on collected coordinates, the three-dimensional diffusion form of slurry was sketched, which were curved surfaces with four kinds of colors. The test results show that soil pressure and seepage pressure increase continuously during grouting while decrease gradually when grouting is stopped. The yellow and red grouting veins respectively formed by the first and the fourth time grouting test have larger size and span. The interaction of multiple grouting are mainly reflected in injection pressure and the distribution of grouting veins. The conclusions play a guiding role on developing grouting theory to some extent.

In order to analyze the diffusion mechanism of single grouting in fault, a large sized test device was developed to conduct simulated grouting diffusion test in fault medium by single injection pipe. At the same time, the real-time key parameters including injection pressure, injection rate, soil stress, seepage stress, and effective stress were acquired. In addition, the fault medium was excavated by nine sections, and the three-dimensional diffusion form of slurry was therefore sketched. It can be concluded that the soil stress, seepage stress and effective stress increase continuously during grouting while decrease gradually when grouting is stopped. The volume of injected cement and waterglass slurry is 7.3% of the volume of fault medium. The the consolidation body of grout with the maximum thickness of 133 mm is in the section of the -50 mm. Based on test conclusions, four suggestions are proposed for the design and application of grouting engineering.

To clarify the strength of fault gouge with preset structural plane after strengthening by cement and sodium silicate grout, a test device was developed. The grouting tests were therefore conducted under the conditions of different structural plane angle, ratio of C-S grout and injection pressure. It can be concluded that the uniaxial compressive strength of samples with α=0°, 45° and 90° increased by 156%, 400% and 50% after grouting, respectively. The strength of samples with α=45° were relatively low both before and after grouting. By the extremum difference analysis method, ratio of C-S grout is confirmed to be the most important factor followed by structural plane angle and injection pressure to influence the strength of samples. Compression failure characteristics of typical samples were analyzed. It was found that grout veins played a role of skeleton during the compression process. In terms of strengthening mode, strengthening effect and the dominant factor, the strengthening characteristics of cement grout, and C-S grout are contrasted. By using the cement grout, structural plane angle is the most important factor to influence the strength of samples, which is different from C-S grout.

This paper presents the results of intensive laboratory testing program investigating the effects of wetting on the drained shear strength and deformation characteristics of silty sands. The materials used were clean medium to fine grained Nile River bed sand and plastic Nile silt. The sand was mixed with 4%, 8%, 12%, 16%, 25% and 40% by dry weight of the Nile silt. The test specimens were prepared at two relative densities 30% and 79.4% and drained direct shear tests were performed on air dry and wetted “submerged” specimens. Results from the tests, i.e. shear stress versus displacement and volume change versus displacement, were analyzed and discussed. The dry specimens showed compression and then dilation during shearing. The volume change behavior of wetted silty sands depends on the silt content and the relative density. With silt content up to 25%, the wetted loose silty sands compressed during shear whereas the wetted dense mixtures showed compression and then dilation during shear. The wetted specimens with fines content of 40% showed compression only during shear. The wetted specimen with (sand + 40% fines) behaved like fine grained soil. Significant drop in shear strength caused by wetting has been measured for all tested specimens. The drop in shear strength was greater for the dense specimens compared to the corresponding loose ones. The drop showed general trend of increase with fines content.

The surfaces of unbound granular materials are often rough and a discrete element modeling of rough granulates is very important to understand the behavior of unbound granular materials. But the existing particle flow modeling rarely consider the effect of particle size distribution on mechanical properties of unbound granular materials. This paper presents an absolute distribution simulation method to generate a three-dimensional particle flow model. In contrast to the conventional particle generation method, the present method was incorporated into a DEM code to investigate the permanent strain response of the granular materials of different particle size distribution. A series of numerical simulation results has been conducted to get the optimum particle size distribution of granular materials under cyclic loading. The results showed that the particle size distribution was significantly correlated with the permanent deformation of unbound granular materials.

The impacts of soil contamination on the behavior of pile group driven into clayey soils and subjected to a combination of axial static and lateral cyclic loads have been investigated in this research. Mechanical model was prepared in order to study the behavior of pile group, 2 × 2. Tests were performed on a free headed pile with a ratio of eccentricity to embedded length (e/L) of 0. 334. The piles are embedded in intact and synthetically contaminated soils. The intact clayey soil samples were contaminated synthetically with industrial wastewater of 10%, 20%, 40%, and 100% from the weight of water used in the soaking process of soil samples, which continued for 30 days. It was observed that different percentages of contaminants have significant effects on the vertical and lateral displacements of the pile group. It was concluded that, the vertical displacement of piles cap increased by 5.5% to 26.6% as the percentage of contamination increased, while the lateral resistance of the pile group decreased by 5.9% to 23.5% with increasing the concentration of contamination. Furthermore, the ratio of permanent displacement to the total displacement varied by 29% to 33% as the percentage of contamination in the soil increased. The efficiency of pile group ranged between 85% and 96%.

Expansive soils in Saudi Arabia have received wide attention in recent decades, following the rapid urbanization of rural and agricultural parts of the country. Wadi Al Dawasir region located at the south part of Riyadh where its soil formation consists of mudrock formations. The behavior of mudrock is tending to be expansive in some parts while the other is not. According to that, this region inflicted serious damages to some light structures, roads and boundary walls. This research is aimed to study the engineering characteristics of the different mudrocks at this region including the basic geotechnical parameters as well as swelling behavior under oedometric loading conditions. Mudrock characteristics are defined with its swelling potential and swelling index. Prediction of heave values for light structures constructing on this types of swelling formations are calculated to find the better solution to reduce the risk of potential swelling distress for future constructions at this site. Recommendations are given to geotechnical engineers for preliminary investigations on this type of mudrock formations to predict its characteristics against swelling prior to perform more detailed of soil investigations of their projects.

It is a well established fact that, both pore size and volume govern the density and particle size characteristics of any soil. For clayey soils, higher densities followed by lesser particle size result in low pore volumes. However, not many studies were conducted on how these pore characteristics alter with variations in density and particle size. This paper presents the results of a study conducted to understand the effect of compaction effort on the pore size and pore volume characteristics on two semi-arid expansive clays. These two clays selected represent soils with different degrees of expansivity, particle sizes and mineralogy. Mercury intrusion porosimetry tests were conducted to study the pore size characteristics at 100, 95, 90, 85, 80, 75 and 70% of maximum dry density (MDD) at corresponding optimum moisture content values. Both pore volume and pore size were analysed with varying density characteristcs and particle sizes. It was observed that in case of samples conducted at 100% MDD, about 50% of the pores were larger than 0.1 µm and this value increased with reduction in density. The current observations assume practical importance especially in the wake of microbial treatments for soils where the the passage of microbes depends on the pore size and more specifically pore throat size.

This paper investigates the effects of sample preparation method on the density and California bearing ratio (CBR) of a cohesive soil. The samples were prepared at two moisture contents (dry and wet of optimum) by consolidation and compaction methods with various efforts (energy). The density and CBR of these samples were than measured and compared. Results of these tests indicate that, at dry of optimum, samples prepared by compaction method yielded higher density and CBR than samples prepared using consolidation method. On the other hand, at wet of optimum, the density and bearing capacity of samples prepared using compaction method were lower than samples prepared by consolidation method. It is evident that over-compaction occurred for samples prepared at wet of optimum using compaction method.

Mining is one of the major economic activities in Australia, which produces millions of tonnes of waste materials every year. Mine tailings derived from crushed waste rock are generally utilized as backfilling material to fill the underground voids created during mining operations. Generally, additives are used to enhance the engineering behaviour of soils and concrete. Cement is one of the most popular additives used to improve the properties of soils. Lately, there have been attempts to use pozzolanic materials such as fly ash and slag to partially replace cement. Excessive cement usage in soil may be reduced by using supplementary cementitious materials such as fly ash and slag, blended cement and geopolymers in some geotechnical applications, which should lead to environment sustainability and substantial cost savings. This paper summarizes the effectiveness of three type of binder in paste fill in terms of their strength and stiffness.

Differing from common vibration testing facilities, bucket with limited mass and stiffness is used as reaction of centrifugal shaker to trigger reduced scale earthquakes. Dynamic interaction between centrifuge shaker and bucket is inevitably generated as a crucial issue for centrifugal shaker development, especially large scale. Based on the robust control strategy and general design of 1-D centrifugal shaker, an equivalent mathematic model for centrifugal shakers was developed and the corresponding transfer function was derived for analyzing the dynamic interaction of centrifugal shaker and bucket. A series of numerical analysis using the transfer function was performed to understand the influence of main parameters of bucket on the performance of centrifugal shaker through the dynamic interaction. A visible oscillation was observed around the first modal frequency of bucket. The results show that increases in the mass ratio or damping ratio of bucket are effective means to mitigate the oscillation, and the recommended parameter values are 4 and 0.1, respectively. The developed model and analyzed results provide references for optimal facility design and numerical simulation of dynamic centrifuge tests.

Granular materials are usually used in low traffic pavement structures as base layer or sub-base layer. The influence of the fine content on mechanical behavior is significant as well as the water content. In this study, based on the test results, a proposed empirical-analytical model was used to determine the permanent axial deformations of Missillac sand in repeated load triaxial tests (RLTTs). The model was also used to simulate the other experimental results existing in the literature. Globally, the results show a good capacity of model to estimate the permanent deformation behavior of granular materials.

This paper presents a study of a uniform dry sand compacted by the pluviation method and submitted to different isotropic and anisotropic stress paths. The stress states were performed in two distinct triaxial cells using specimens of 100 mm and 150 mm diameter in order to assess also the scale-effects. The small strain stiffness for each stress state was evaluated in both triaxial cells by bender elements which were assembled vertically and horizontally for the comparison of the shear wave velocity in the two directions. In the specimens of 100mm, additionally to the bender elements in the vertical direction, accelerometers were used for the improvement of the results accuracy. All tests results were analysed in order to assess the initial fabric (inherent) anisotropy and the induced anisotropy by the different anisotropic stress paths.

In practice, the soil is subject to more than one shear stress in many cases. For instance, the soil in an embankment is subject to a static shear stress along sloping direction, and the sloping direction is usually different from the direction of an earthquake loading. Therefore, there is a necessity to investigate undrained soil behaviors under shear stresses along multiple directions. This paper employs the first commercially available bidirectional direct simple shear apparatus (VDDCSS) to investigate the soil responses of Leighton Buzzard sand under two directional shear stresses. Sand samples are first subject to a static shear stress under drained conditions along different directions from 0° to 180°, followed by a monotonic or cyclic shear stress along 0° until failure occurs. In static tests, the soil strength is the lowest when the angle between these two shear stresses is near 90°, and the strength is the highest at 0°. In addition, a smaller angle leads to a more brittle response, and a greater angle leads to a more ductile response. In dynamic tests, liquefaction resistance is decreased from the angle of 0° to 90°, and then increased from 90° to 180°.

The objective of this research paper is to create new hydrophobic material using polymers for reducing swelling and shrinkage potential of bentonite (montmorillonite) clay. Three low cost polymers viz. polyvinyl alcohol (PVA) and polyvinyl chloride (PVC) and β-Cyclodextrin is used in present investigation in proportion of 2%, 4% and 8% of dry weight of soil. Series of swelling and shrinkage tests (paraffin-coated wax method) as per IS code was carried out to determine swelling and shrinkage parameters. The selection of polymers is based on clay-polymer interaction and cation exchange capacity. Post analysis of clay-polymer complexes was analyzed to study the change in mineral concentration and exchangeable cations by EDAX and CEC tests. From the results it is concluded PVA reduces swell and shrinkage potential up to 60–65% and with efficient use of soil-chemistry interaction much better results can be obtained for expansive clays.

Through laboratory tests of unconfined compressive strength (UCS) on the five types of cement-soils with different cement contents and curing times, the stress-strain curves and the UCSs of different cement-soils were obtained. The influence of boundary conditions on the UCS of silt cement-soil was analyzed. Moreover, the curve fitting equations of the five different cement-soils with different cement contents and curing times were given. Test results indicate that the stress-strain curve of cement-soil consists of ascending and descending parts. Comparisons of the peak strain of different cement-soils show that the gravel cement-soils have the minimum peak strains, around 0.01, while the peak strains of other cement-soils (silver sand cement-soil, silt cement-soil, clay cement-soil and muck cement-soil, respectively) are around 0.016~0.03. The UCS of silt cement-soil without both ends oiled is larger than that with both ends oiled, and the strength ratio is about 1.1~1.2. Less than 60 days, the UCS of cement-soil increases remarkably with the increasing curing time. The ratios of the secant modulusE₅₀ to the UCSf_cu are about 25 to 140 and are slightly influenced by the curing time.

The majority of engineering problems is based on the analysis of soil properties determined from compression tests, from which the soil behaviour is mainly affected by the change in the initial moisture content, void ratio, scale and overburden stress. On the other hand, setbacks encountered are with the sample scale and the initial moisture content effects on engineering applications in field conditions. Accordingly, in this study, the effect of both the initial moisture content (ranging from 55% to 105%) and the sample scale on the compressibility parameters was investigated. The outcome showed that there is a positive correlation of 0.546 between the initial moisture content and the coefficient of consolidation (c_v), and 0.162 and 0.026 with the compression index (c_c) and the coefficient of volume of compressibility (m_v) respectively. Also, c_c with the sample scale has a negative correlation factor of -0.115 and -0.085 (for sample height and diameter respectively). This shows that as the sample height and/or diameter increases, c_c has a tendency to decrease. It was similarly observed that m_v fluctuates with an increase in the sample scale and pressure until a pressure of 220kPa±3.7kPa, where the value decreases. Hence, there is no significant influence between c_c and m_v.

The following article represents results obtained from foundation bearing capacity analysis carried out by international and Kazakhstan researchers. Evaluation of soil bearing capacity that used in USA and Europe based on Terzaghi-Prandl solution and further improvement of Meyerhof. The solutions considered in this article based on an assumption of stiff wedge propagation under foundation base made of compacted soil. Advancing of the following wedge further down impacts on surrounding soil up to the critical state. The use of approximate formulas for bearing capacity determination allowed for derivation from the theory of plasticity or experimental data. The design code for basements and foundations in Kazakhstan is planning to shift into Eurocode “Geotechnics-7”. In that case, an approach of foreign researchers used in studies conducted by the authors, analysis of differences between the regulations and principles of design to Eurocode.

Sabkha soils are recent saline sediments characterized by low strength and high compressibility. They become impassable when dampened, which indicate that this type of soil is susceptible to collapse upon flooding. The present study deals with the collapsibility of sabkha soils using conventional and modified oedometers. The modified oedometer which allow water to percolate through the consolidating sample demonstrated its ability to detect the collapse potential of saline soils.The results showed that the studied sabkha soil is moderately collapsible.

In this paper, the behaviour of geosynthetic-reinforced controlled modulus column-supported embankments is studied for different distributions of loadings induced by arching on the load transfer platform (LTP). This study proposes a mechanical model for idealising the response of LTP-soft soil-column system, by representing each sub-system using commonly used mechanical elements such as rough-elastic membrane, beam, and spring. The soil arching effect is incorporated in the model to determine the deflection of the soft soil as well as mobilised tension in the geosynthetics more accurately. The effects of the column stiffness and consolidation of saturated soft soils are also incorporated in the model. Moment and shear force in the LTP, tension developed in the geosynthetics, and settlements of the improved soft ground are predicted using the proposed model. To evaluate the proposed model, a parametric study is conducted to investigate the influence of different pressure distribution due to different arching theories. It is observed that the pattern of distribution of the arching loads affect the performance of controlled modulus column-supported embankments significantly.