Soft Clay Soil Research Articles

Enhancement of pavement sections on soft clay soils to sustain overloading

Enhancement of pavement sections on soft clay soils to sustain overloading

Effect of Engineering Properties of Soft Clay Soil Stabilized with Limestone, Eggshells Powder and Eggshells Ash

Effect of Engineering Properties of Soft Clay Soil Stabilized with Limestone, Eggshells Powder and Eggshells Ash

A thermodynamic-based model for modeling thermo-elastoplastic behaviors of saturated clayey soils considering bound water dehydration

The non-isothermal deformation of soft mudrocks or clay soils is one of the most critical issues in energy and environmental related geotechnics. Clay-related geomaterials hold complex microstructure and mineral composition, which brings difficulty in investigating their thermo-mechanical behaviors. Previous studies pay little attention to the difference between a thermal plastic strain and the strain from clay dehydration. In this study, a new constitutive model is proposed for describing the thermo-elastoplastic behaviors of clayey soils under water-saturated condition. The effect of temperature variation and mechanical loading on elastoplastic strains and dehydration are investigated. The thermodynamics laws and the unconventional plasticity are applied to quantify the thermo-mechanical behavior. The irreversible strain is captured by using Cam-Clay plasticity and subloading yield surface concept. The dehydration strain is described by utilizing a novel method based on generalized thermodynamics approach and Helmholtz free energy function. The internal variables, and the first and second laws of thermodynamics are applied in the model. The hardening rule is established by implementing the laws of physical conservation, energy dissipation, and plastic flow. The proposed model is validated using specially designed thermal consolidation tests on laboratory prepared heavily consolidated clayey soils and some published data of clayey soils with different geological origins.

PENGARUH PENGGUNAAN ENDOCARP SAWIT UNTUK STABILISASI TANAH LUNAK PEATLAND

During this use Endocarp mostly produced by the oil palm plantation industry. Research is done by mixing Endocarp oil palm that has been sun-dried with maximum dry conditions along with soft clay soil with a content of Endocarp 4%, 6%, and 8%. The sample used in this study is a samples undisturbed , and samples disturbed prepared in the laboratory by mixing clay and Endocarp with a variation of the mixture used is 4%, 6%, and 8% from one bag of clay weighing 2 kg. There is a mix Endocarp the following results were obtained: equal to 1.37 gram/cm3 with a water content of 24.72% (original soil). The CBR value of the mixture Endocarp this study 4%, 6%, 8% obtained the result that the CBR value is mixed Endocarp 4% has the greatest CBR value, which is equal to 7.99% (Unsocked) and 6.69% (socked). The UCT value of the soil will increase in the presence of a mixture Endocarp until mixed Endocarp added by 4% and the UCT value will decrease after the mixture Endocarp above 8% fiber content, maximum UCT value is produced in the mixture Endocarp 4% with a qu value of 0.9295 kg/cm2. The value of the soil shear resistance (su) on the test Vane Shear Test continued to improvement in the mixture Endocarp as much as 4% worth 92 kPa (25 blow condition).

Shear Strength Prediction of Treated Soft Clay with Sugarcane Bagasse Ash Using Artificial Intelligence Methods

Soil shear strength is an essential engineering characteristic used in designing and evaluating geotechnical structures. In this study, we intend to analyse and compare the performance of the Genetic Algorithm - Adaptive Network-based Fuzzy Inference System (GANFIS) and Artificial Neural Networks (ANN) in predicting the strength of soft clay. Case studies of 144 soft clay soil samples from Sarang Buaya, Semerah, Malaysia, were utilised to generate training and testing datasets for developing and validating models. RMSE and R have been employed to validate and compare the models. The GANFIS has the highest prediction capability (RMSE=0.042 and R=0.850), while the ANN has the lowest (RMSE=0.065 and R=0.49). From a comparison of the two models, it can be stated that GANFIS is the most promising technique for predicting the strength of soft clay.

The Perception of Farmers on Soil Erosion and Conservation Measures in the Surrounding Areas of Lake Ziway, Central Rift Valley of Ethiopia

The level of sediment deposited in the Lake Ziway is increasing through time as a result of soil erosion, and eventually the depth of the lake has decreased. Therefore, the objective of the study was to assess farmers’ perception of soil erosion and the conservation measures to the surrounding areas of Lake Ziway in the central Rift Valley of Ethiopia. The survey was made using purposive sampling techniques. The survey has considered the 14 Kebeles from the 3 districts adjacent to the lake. From each Kebele, 10 respondents were selected randomly. Totally, 140 respondents were selected from the community. The descriptive statistic was used to compare the dependent variables. The majority of respondents (92.2%) have observed the presence of soil erosion in the study area. The hillsides and slope areas are the major sources of soil erosion, according to 80% of the respondents. The respondents that have identified the most and least susceptible soils to erosion by their textural classes are sand soil (Biyyo Chirecha) (57.1%) and soft clay soil (Biyyo Bole) (1.4%), respectively. The soil erosion is increasing in their cultivated land and surrounding areas. The study has found that most of the respondents (86.5%) are participating in soil and water conservation activities. Leucaena leucocephala, Faidherbia albida, Azadirachta indica, and Schinus molle are the dominant tree species planted in the study area for soil and water conservation purposes. In conclusion, there is heavy soil loss due to erosion on cultivated land from the upland which directly deposited to Lake Ziway as sediment which decreases the lake depth. The study recommends that appropriate soil and water conservation measures and land management should be implemented on erosion prone areas in the Lake Ziway watershed with full participation of all stakeholders including the local farmers.

An empirical formula for the accumulative deformation of saturated clay under different cyclic loading frequencies

Road and subway tunnels in soft clay soils subjected to traffic loading often cause lager settlement. It can pose danger to the surrounding buildings and structures. Hence, it is necessary for engineers to correctly predict the long-term deformation of saturated clay foundations under cyclic loading. In this paper, a series of dynamic triaxial tests were carried out on Nanning clay to investigate the effect of loading frequency and cyclic stress on axial strain accumulation of clay under undrained condition. Results show that loading frequency has a great effect on the axial strain accumulation of clay. Based on the experimental results, an empirical formula for calculating the accumulated deformation of saturated clay under cyclic loading was presented.

One-dimensional large strain electro-osmotic consolidation model based on multi-field coupling

Current electro-osmotic consolidation theories and numerical models usually ignore the variation of chemical fields and are applicable to soft clay soils with a single chemical composition. In this paper, a numerical model, called EC4, is presented for one-dimensional large strain electro-osmotic consolidation with coupled electrical-hydro-chemical fields. The algorithm accounts for non-linear variation of soil parameters, ion transport and a variety of chemical reactions, including ionization-neutralisation reactions, ion adsorption–desorption reactions and electrolytic water reactions at electrodes. The laboratory electro-osmotic consolidation tests on kaolin samples with different NaCl concentrations were conducted. The laboratory results were used to verify the accuracy of EC4. Then EC4 was implemented to example problems to investigate the effect of important chemical characteristics on the electro-osmotic consolidation. The effects of electrical voltage and initial pH on settlement, degree of consolidation, excess pore pressure and energy consumption of multi-field coupled electro-osmotic consolidation were further analyzed.

A Study On Stabilization of Soils by Using Egg Shell Powder

Using alternative materials, which have better engineering quality than traditional materials and are more cost-effective, has received a lot of attention recently. One of the most crucial components in many building projects, such as earth canals and earth dams, is soil. The fact that soil might offer all the resistant qualities required for a project highlights the value of several techniques used to enhance soil quality. The vast majority of construction projects employ clay soil. Because clay soils, especially soft clay soils, have good plastic qualities, their shear strength, compressive strength, and volume changes decrease as moisture content rises. Structures generally suffer permanent harm as a result of these issues, which emphasises how crucial soil improvement is. The use of such refuse and industrial wastes and their subsidiary products as alternatives to construction materials may effectively contribute to environmental preservation and minimize their negative effects on the Environment, especially in light of the millions of tonnes of waste produced annually across the nation, which not only poses the problem of disposal but also adds to environmental contamination and health risks. In the current study, eggshell powder was utilized as a waste to mix with soil in order to examine clay soil's index characteristics, compaction, and shear strength at various mixed proportions. The shear strength of soils that had already been tested was then contrasted with experimental specimens that had been combined with various ratios of eggshell powder.

Effectiveness Of Portland Cement Type 1 In Stabilizing Soft Clay Soil As Subgrade For Road Construction

Sawah Lunto – Talawi road segment (STA 139 + 700 m) in Sawah Lunto city, West Sumatera province has sustained major damages and been the scene of several accidents since the past few years. The degression of soft clay subgrade, which has a limited bearing capacity and makes it structurally impractical to sustain road construction, was discovered to be the source of these damages. As a recent option for enhancing soil qualities, soil stabilization by employing a variety of pozzolanic and industrial materials has gained popularity. The objective of this study is to investigate the effectiveness of Portland cement type 1 as stabilizing material in improving the soil properties and carrying capacity requirements for soft clay soil used as subgrade in road construction. To accomplish the objectives of this study, a laboratory testing procedure was implemented. Unconfined Compressive Strength (USC) values on natural soil and treated soil with Portland cement type 1 admixture were measured and compared during laboratory experiments. Soft clay soils were stabilized with varying percentages of Portland cement type 1 with the proportions of approximately 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 10% by dry weight of soil during a 7-days curing period. Laboratory testing were performed in compliance with Indonesian National Standard (SNI): SNI 3420-2008 for testing Unconfined Compressive Strength. According to the results of laboratory testing, the UCS values increased roughly from 0.634 kg/cm2 (undisturbed natural soil) to 2.832 kg/cm2 (treated soil) by adding 3% of Portland cement type 1, and up to 8,024 kg/cm2 (treated soil) by adding 10% of Portland cement type 1. Based on the findings, it can be demonstrated that Portland cement type 1 can enhance clay soil's properties used as a subgrade for road construction, can create more stable road conditions, and can ultimately meet the technical feasibility requirements for the subgrade carrying capacity, particularly at the Sawah Lunto - Talawi road segment (STA 139 + 700 m).

Behavior of Piles Reinforced by Geosynthetics Under Lateral Load

This paper introduces the results of eleven lateral pile loading testsperformed on concrete piles reinforced with different materials such as FRP bars,geosynthetics geogrids, and composite of two materials to check their efficiency incarrying the lateral load. The lateral loading pile test was applied on three groupsconsisting of ten reinforced concrete pile specimens, and control concrete pilespecimen reinforced by steel bars. All samples have the same dimensions (150 mmdiameter x 1050 mm length). This research assumed that the pile was placed in avery soft clay soil and rested on a crushed stone layer, so the frictional effect of thesoil was neglected. A comparison has been carried out between experimental resultsfor all samples. The experimental results illustrated that the lateral loads carried bypiles were increased up to 25.3% by using FRP bars, biaxial geogrid, and uniaxialgeogrid. Moreover, a non-linear finite element analysis was verified by Abaqusstandard software and achieved a great rapprochement with the experimental results.Finally, a comparison was carried out between the reinforcement cost for allsamples, which showed that using these composite piles decreased its cost up to59%.

Utilization of bottom ash waste as a granular column to enhance the lateral load capacity of soft kaolin clay soil.

Implementation of industrial wastes such as bottom ash in ground improvement can be cost-effective and environment-friendly. Ground improvement is an effective method of mitigation to improve problematic soils including soft kaolin clay soils as the problematic soils always expose to the severe settlements, low shear strength, immoderate plasticity, greater compressibility, dispersivity, bulging, erodibility, and susceptibility to climatic variables. Several studies conducted on the granular column using the bottom ash column. However, only a few studies have reported findings coherent with the statistical analysis. In this study, the lateral load capacity of bottom ash column-kaolin clay has been conducted. Coherently, the reinforced kaolin clay samples were tested via particle size distribution, Atterberg limit test, relative density, compaction test, permeability test, unconfined compression test, and unconsolidated undrained triaxial test with the single and group of encapsulated bottom ash columns with the geotextile encasement and a prediction model was developed. The effect of a number of columns, column diameter, column height, area replacement ratio, height penetration ratio, height-diameter column ratio, volume replacement ratio, and confining pressures on the shear strength of the single and group of encapsulated bottom ash columns have been investigated. The findings showed the effectiveness of using the bottom ash columns at various number of column, column diameter, column height, area replacement ratio, height penetration ratio, height-diameter column ratio, volume replacement ratio, and confining pressures can enhance the shear strength of the soil up to 77.00% at the optimal utilization of single encapsulated bottom ash column of 10-mm diameter and 80-mm height. Therefore, the study proved that the utilization of bottom ash waste as a granular column can significantly enhance the lateral load capacity of soft kaolin clay soil.

The behavior of micropiled raft foundations subjected to combined vertical and lateral loading: numerical study

The micropiled raft offers a foundation system that combines the advantages of the conventional piled raft and the efficient installation of micropiles. In this paper, a comprehensive numerical analysis was conducted on the behavior of micropiled rafts under combined vertical and lateral loading using finite element modeling. A numerical model calibrated against full-scale axial and lateral field tests is used to conduct the analysis. The soil profile was soft clay soil underlain by a layer of dense sand. Numerous cases were analyzed to assess the lateral performance of micropiled rafts while considering several factors that may affect the performance, such as micropiles spacing, raft thickness, the magnitude of vertical loading, micropiles length, and their arrangement. The difference between the lateral performance of a primary micropiled raft and that of an existing raft enhanced by underpinning micropiles was also investigated. The lateral load capacity of the micropiled raft, the bending moment, and the shear force along the micropiles depth were estimated. Moreover, the load-sharing ratio between the micropiles and the raft was assessed. Based on the parametric study results, significant guidelines for choosing suitable micropiled raft configurations for initial design purposes were provided.

The Effect of Jet Grouting on Enhancing the Lateral Behavior of Piled Raft Foundation in Soft Clay (Numerical Investigation)

Soft clay soils cannot usually support large lateral loads, so clay soils must be improved to increase lateral resistance. The jet grouting method is one of the methods used to improve weak soils. In this paper, a series of 3D finite element studies were conducted using Plaxis 3D software to investigate the lateral behavior of piled rafts in improved soft clay utilizing the jet grouting method. Parametric models were analyzed to explore the influence of the width, depth, and location of the grouted clay on the lateral resistance. Additionally, the effect of vertical loads on the lateral behavior of piled rafts in grouted clay was also investigated. The numerical results indicate that the lateral resistance increases by increasing the dimensions of the jet grouting beneath and around the piled raft. Typical increases in lateral resistance are 11.2%, 65%, 177%, and 35% for applying jet grouting beside the raft, below the raft, below and around the raft, and grouted strips parallel to lateral loads, respectively. It was also found that increasing the depth of grouted clay enhances lateral resistance up to a certain depth, about 6 to 10 times the pile diameter (6 to 10D). In contrast, the improvement ratio is limited beyond 10D. Furthermore, the results demonstrate that the presence of vertical loads has a significant impact on sideward resistance.

Evaluating the Effectiveness of Nonwoven Geotextile-Encased Cinder Gravel Column in Improving Load-Bearing and Deformation Characteristics of Soft Clay

Application of vertically installed columnar materials made of natural gravels or crushed aggregate is one of the commonly implemented practices to improve the performance of soft clay grounds under footing load. Alternative materials like cinder gravel also plays a reinforcing role when blended with soft clay. However, information on the precise extent to which a vertically installed cinder gravel column is effective in improving the properties of a clay foundation and its potential response to the permanently applied footing load has not been well documented in the literature. Hence, the current study specifically aimed at evaluating the effectiveness of geotextile-encased cinder gravel column in improving deformation and bearing capacity of soft clay ground. The experimental model which considered installation of a single geotextile-encased cinder gravel column into soft clay was considered. A cylindrical steel container was used in designing the experimental test. The container was filled with clay soil and the cinder gravel column was vertically installed through a replacement method. Finding of the study revealed that ultimate load-bearing capacity of the soft clay foundation after being reinforced with conventional cinder gravel was 1.85 times that of the untreated soft clay soil. The load-carrying capacity of the clay soil decreased with increment in diameter of the column whereas it is directly related to the volume replacement ratio. With regard to directional improvement, the vertical reinforcement performs better than the horizontal geotextile strips in cinder gravel column from bearing capacity improvement view point. In lessening settlement, however, application of horizontal geotextile discs at spacing ranging between half- and full-column diameter overweighs performance of the vertical encasement. In summary, application of geotextile encasement to the top 75% of the clay thickness is sufficient to come up with optimum improvement in bearing capacity and encasing the entire thickness is not necessarily required.

Two-dimensional study of the inclusions of skirt sand and deep cement piles to improve the load‒displacement behavior of circular foundations on soft clay soil

The bearing capacity of clayey soils is low, and the induced settlements play an important role in estimating the stability of structures built on these weak soils. Therefore, these clayey soils need improved mechanical strength. In this study, a two-dimensional finite element model was used to improve the bearing capacity and settlement of soft clay soil by employing skirt sand piles, and the results were compared with reinforced cement piles. Skirt sand piles consisting of thick sand cores and closed tubes placed under a circular shallow foundation with a steel plate of suitable dimensions, as well as reinforced cement piles of different lengths and in nondrained situations were studied. These calculations were carried out using PLAXIS 2D software, and a series of finite element analyses were performed. The Mohr‒Coulomb and hardening soil models were used to model the fine-grained and granular soils, respectively. A linear elastic model was used to simulate the circular plate and skirt components. Previous experimental studies were used to validate the numerical model. The experimental test and the 2D axisymmetric model agree well. According to the assumptions, the efficiency of skirt sand piles is superior to that of deep cement piles. In addition, increasing the length of SSP skirt sand piles has a significantly greater effect on improving the bearing capacity than increasing the length of deep cement piles. As a consequence, the failure modes of piles with skirt sand were determined. It was found that the failure mode when skirt sand piles were tied into clayey soils occurred in the underlying sandy soil layer as a general shear failure.

Geotechnical behavior of encased stone columns in soft clay soil

Geotechnical behavior of encased stone columns in soft clay soil

Consolidation Attributes and Deformation Response of Soft Clay Reinforced with Vertical Scoria Drains under Road Embankment

Application of vertical drains in soft clay soils is a common practice widely known to facilitate the consolidation rate. To overcome the adverse impact of a long-lasting consolidation process, highly permeable materials such as sand and crushed aggregates are used as drains. However, limited information exists regarding the applicability of scoria gravel as a vertical drain that no concisely documented information is observed in the literature. This study hence aimed at investigating suitability of scoria as a vertical drain in perpetuating the consolidation process of soft clay under highway embankment. Finite element-based numerical simulation was used to model the drain. The model was carried out by using 3D version of Plaxis software. In order to incorporate the effect of gradual load increment on the consolidation rate, the staged construction approach was employed. Both the square and triangular installation patterns were considered in the model in order to explore the critical effects of the drain installation pattern on the rate of consolidation. The numerical analysis also included varying dimensions of the vertical drain so as to investigate the effects of the dimension parameters of the vertically installed scoria drains. The conducted numerical analysis revealed that the rate of consolidation was considerably accelerated with provision of a group of scoria drains. With increase in the diameter of the drain, the consolidation rate increases, whereas the consolidation rate is inversely related to increase in drain spacing. For the drain installed at a spacing of 2 m, a diameter of 0.4 m, and a length of 8 m any arbitrary settlement magnitude is achieved 25 days earlier than the case without drains. Besides, incorporation of scoria drains lessens the pore pressure developed. The comparative analysis conducted on the effect of drain arrangement revealed that no considerable difference was witnessed in the performance of the square and triangular installation patterns even though the consolidation rate remains slightly faster in the case of the triangular installation pattern.

Numerical study on vertical bearing behavior of pedestal pile’s embedded in fine grained soils

The aim here is to investigate the behavior of pedestal/belled piles present in soft clay soil through numerical analysis using Plaxis 2D software. The method used here was based on finite element analysis to simulate pile-soil interactionandtoanalyzethepile’sbehaviorunderdifferentloadsbyvaryingparameterssuchaslengthembedded inthesoilandalsothediameteroftheshaft.Theresultsindicatethatincreaseinlengthaswellastheshaftdiameter of the pile enhances the pile’s load-bearing capacity. The study also shows that the pedestal/bell pile can improve the pile’s performance in soft clay soil by reducing the soil’s displacement and increasing the pile’s axial capacity in comparison to conventional straight pile. The study concludes that the pedestal/belled pile is a promising option for the foundation of structures in soft clay soil, and the numerical analysis using Plaxis 2D software can provide quick and reliable predictions of the pile’s behavior. The study’s findings can be useful for optimizing the design of pedestal/belled piles in soft clay soil and improving the efficiency and safety of foundation systems in similar geotechnical conditions.

Numerical Simulation of Embankment Settlement in Vacuum Preloading Systems

In Indonesia, the construction of the road has challenges because the road was built on soft clay soil. The vacuum preloading method was used to improve the shear strength and compressibility properties of soft soil in this project. Moreover, what needs to be a concern for practitioners is the issue of increasing simulation accuracy in predicting soil settlement in a vacuum preloading system. The research objective of this study was to determine changes in soil settlement behavior that occurred from the vacuum preloading system using a numerical simulations Geostudio with the 2D Multi Drain-Plane Strain approach and the settlement result of the simulation will be compare with instrumentation data. In this study the vacuum pressure distribution is modeled using water total head negative pore water pressure and the pressure value used following vacuum gauge data in the field with distribution approach is 100% at the surface of the sand platform, 85% to a depth of 5 m, then 60% to the end of the PVD. Based on the simulations, the conlusion is the vacuum pressure applied along the vertical drainage is not modeled constant, but changes with depth, the value of 60% at the bottom of the vertical drainage is quite representative of the conditions in the field and the settlement from the simulation is quite good at approaching the field observation with a prediction of the settlement due to vacuum preloading of ±0.93 m, when compared to the field observation data there is a difference of about 1.6%.