Behavior Of Clay Soil Research Articles

A Strain-Controlled Finite Strain Model for CRD Consolidation of Saturated Clays Considering Non-Linear Compression and Permeability Relationships

Consolidation is the combined phenomenon of the compression and groundwater seepage of clay. Accurate evaluation of the consolidation characteristic is essential for the design, construction, and long-term stability of geotechnical structures. In this study, a strain-controlled non-linear finite strain model for constant rate-of-deformation (CRD) consolidation was developed for quickly and reliably predicting the consolidation behavior of clay soils. The model can account for any form of non-linear compression and permeability relationships, thus considering variations in the coefficient of consolidation. Being strain-controlled, it overcomes the limitations of stress-controlled models which require complex numerical iteration. The validity and accuracy of this model were verified through rigorous comparisons with both numerical simulations and experimental data. For normally consolidated soils, a non-linear e-lgσ′compression model was used instead of a linear compression model. For overconsolidated soils, the Harris function compression model was determined to be recommended to overcome the discontinuities in total stress and pore pressure caused by the traditional piecewise e-lgσ′ model. It was also found that determining the steady state of consolidation for normally consolidated soils should use the non-linear method, while the linear method is suggested to be adopted for overconsolidated soils.

Identification of calculated parameters of the Hardening Soil model based on laboratory soil tests

The modern soil model Hardening Soil, which is used in many software complexes intended for solving geotechnical problems, is considered. The model makes it possible to take into account changes in deformation parameters of soils depending on the level of applied stresses and to describe the deformation processes of cohesive soils under complex loading/unloading trajectories.
 The paper also presents tables and graphs obtained during laboratory studies of semi-hard clay "Kyiv marl" in a triaxial system and an oedometer. Based on these data, the soil strength parameters с' and φ', as well as the stiffens modules , , were determined.
 To correlate the results of numerical simulation with the real behavior of clay soil in the Plaxis software complex, using the SoilTest virtual laboratory, a test in a triaxial compression device was simulated and soil parameters were identified. This approach makes it possible to increase the accuracy and quality of calculation results.
 During identification, the parameters that most affect it were analyzed, which made it possible to better understand which parameters and in which ranges to vary in order to achieve the desired result.
 It was determined that the most sensitive parameters are the section modulus of rigidity and the coefficient of destruction Rf. Their percentage sensitivity is 65.9% and 32%, respectively.
 By varying the c' and φ' characteristics during the tests in the virtual laboratory, the destruction of the sample was simulated in accordance with real soil studies. Therefore, it is very important to correctly determine these parameters, because this can lead to an underestimation or, on the contrary, an overestimation of the strength of the soil base.

Effect of mineralogical composition and chemical properties on the consolidation behaviour of clay soils

ABSTRACT Consolidation characteristics like coefficient of consolidation (cv ) and compression index (cc ) are greatly influenced by the clay mineralogical composition of the soil. For the purpose, 20 clay soil samples collected from various locations of Tamil Nadu were subjected to one-dimensional consolidation test, and the clay minerals like montmorillonite, illite, and kaolinite were quantified using soil chemical properties. From the test results, it is observed that cv varies with consolidation pressure σ due to varied mineralogical composition. cv -σ trend decreases for soils with montmorillonite percentage (%M) greater than 42% and increases for soils with illite (%I) and kaolinite (%K) percentages greater than 42% and 41% respectively. The paper also focuses on the effect of CEC and SSA on cv and cc of the clay soil samples. A new correlation for cc in terms of clay mineral percentages and chemical properties (CEC, SSA) has been developed using regression analysis.

A Structural State Model Interpreting the Residual Strength Transition Behavior of Clay Soils

A Structural State Model Interpreting the Residual Strength Transition Behavior of Clay Soils

Kaolinite subgrade strength characteristics variation with RBI Grade 81

The shrinking behaviour of clay soil due to moisture variation causes damage to the foundation of structures, residential, commercial structures and embankment construction. To overcome this problem, the soil needs to be treated to improve its strength and durability of the ground. The best technique is stabilization, which enhances the engineering soil properties, upgrades the shear strength, and reduces the consistency limit. In this present study, Kaolinite clayey subgrade soil is stabilized using Road Building International Grade 81 (RBI), and its effects on the strength characteristics of the soil are studied. Compaction characteristics, Atterberg's limits, Unconfined Compression Strength tests (UCS), and Split Tensile Strength (STS) on the soil samples were performed. The same composites are studied for SEM and XRD results to confirm the morphology of the new compounds formed. Compaction factors increased optimum moisture content (OMC), and the maximum dry density (MDD) decreased with RBI Grade 81 to kaolinite. UCS values increased significantly for the clayey subgrade with the addition of RBI Grade 81. RBI Grade 81 at 8% shows an enhanced upgrade in the clay subgrade's strength compared with the natural kaolinite subgrade. Hence, RBI Grade 81 can be recommended as a potential soil stabilizing agent, particularly for clayey subgrade soil.

Effect of bio-cementation on the strength behaviour of clay soils using egg shell as calcium source

Effect of bio-cementation on the strength behaviour of clay soils using egg shell as calcium source

Mechanical Behavior of Clay Soil Stabilized with Fly Ash and Bottom Ash

Soil is one of the most important aspects of an infrastructure given its functions of receiving and holding structural loads. However, not all soils have good physical and mechanical properties. To overcome those conditions, stabilization of the soil is practiced to meet the technical requirements. This study aims to determine the behavior of high plasticity clay stabilized with lime, fly ash, and bottom ash. These additives can be used as a stabilizing agent to increase soil strength. The percentage of additives varied from 5%–25% then mixed with clay and were tested through the (Unconfined Compression Strength (UCS) test. The UCS test was carried out with 6 treatments, including consecutively non-curing and unsoaked, non-curing and soaked, curing for 7 days and unsoaked, cured for 7 days and soaked, cured for 28 days and unsoaked, and cured for 28 days and soaked. Results show that the UCS value increased along with the span of curing time. Meanwhile, the soaking treatment of the sample decreased the UCS value.

Combined effect of nano-silica and randomly distributed fibers on the strength behavior of clay soil

Combined effect of nano-silica and randomly distributed fibers on the strength behavior of clay soil

Failure analysis of clay soil-rubber waste mixture as a sustainable construction material

Rubber waste (RW) causes serious environmental problems in human societies; however, it has valuable engineering properties, particularly recruited as an additive to construction materials. Hence, the reuse of such wastes is of both geotechnical and environmental importance. In this study, the behavior of clay soil (CS) mixed with RW was evaluated using the unconfined compressive strength (UCS) test. Accordingly, the effect of three rubber shapes, two rubber sizes, and four rubber contents on the UCS, failure modes/mechanisms, strength, modulus of elasticity, failure strains, post-peak loss of strength, and test repeatability were investigated. The findings revealed that, among the three rubber shapes, namely, granular, chips, and fibers, the granular rubber with a larger size than other shapes could more effectively improve the geotechnical properties of CS and produce more repeatable results. Moreover, the CS-RW mixtures showed failure modes/mechanisms different from pure CS ones, depending on the shape of the RW. The RW could also change the CS failure behavior from brittle to ductile. Some practical correlations were further proposed to estimate the strength of CS-RW mixtures. According to the study results, it is recommended to apply granular RW, as a suitable construction material in geotechnical projects in the role of fillers, in view of its failure mode, strength, and low weight along with other positive properties of CS-RW mixtures.

Assessment Principles for the Mechanical Behavior of Clay Soils

The factors that determine the geotechnical behavior of soils are mainly their composition, the size of their grains and their moisture content. The design of a soil structure or foundation project must ensure the shear adequacy of the soil in all phases of construction and throughout the life of the project. However, the shear strength, in general, of the soil is not "constant" but depends on key external factors such as the prehistory of loads, the time and succession of load states, the overpressure of the pore water as well as other factors such as relative density, or any preload, the pressure field, the rate of change of the intensive state, etc. The influence of the deformations as well as the change of the intensive state during the sampling should not be ignored. Unlike other materials, in clay materials the determination of shear strength and its interpretation is a very complex problem. The aim of this article is to search for the mechanical behavior of clay soils (lignite, kaolinite, marl) as shown by the laboratory illustration related with the problems on shear strength of materials, based on the results of experimental research

3-dimension stresses and new failure model to predict behavior of clay soils in various liquid limit ranges

Data analytics are becoming important to better characterize the material behavior. In this study, over 3000 data from the laboratory studies and literature for the field soils were analyzed to quantify the relationship between the density, natural moisture content, shear strength, deviatoric shear stress at failure (3-dimension stress) with the liquid limit (LL). With the increase in the construction of wells, tunnels, piles, and storage facilities, there is interest in determining the safety of soils under multiaxial loading. The range of liquid limit (LL) for the soil investigated varied from 20 to 60%. The ranges of the dry density (γd) and the natural moisture content (MC) for the soils varied from 1.2 to 2.6 g/cm3 and 13 to 56% respectively. The statistical distribution of the data collected varied from normal distribution to Weibull distribution. Vipulanandan correlation model correlated some of the physical properties of the soils. Vipulanandan failure model was used to the failure stresses for the soil and compared to the Mohr-Coulomb failure model and other failure models. Based on the coefficient of determination and root mean square error, the Vipulanandan failure model predicted the results more reliable than the other models. Vipulanandan failure model also predicted the maximum shear strength limit and maximum second deviatoric stress invariant for the soil, whereas none of the other models predicted the maximum shear tolerance for the soil investigated. With the Vipulanandan failure model, the maximum shear strength predicted for the soil was 57 kPa. The maximum second deviatoric stress invariant for the soil in the LL range of 20 and 60% varied from 44 to 30 kPa.

Farklı Havza Sularının Killerin Kıvam ve Mukavemet Özellikleri Üzerindeki Etkisinin Araştırılması

The engineering behavior of clay soils, vary depending on the amount of water they contain. Thesevariations depend on the crystal structure of the clay mineral and the chemical structure of the water in the voidsof the soil. In this study, on the geotechnical properties of high plasticity (CH) and low plasticity (CL) clays theeffects of waters with different chemical structures were investigated. Within the scope of the study, somegeotechnical experiments were carried out on two different clays from Erzurum with high plasticity and lowplasticity and, tap water and water with different chemical structures obtained from three different basin inEastern Anatolia (Fırat Basin, Çoruh Basin and Aras Basin) were used. The consistency limits, standard proctorand unconfined compression tests were carried out on clays, and the experiments were repeated using differentbasin waters and, the results were compared with the test results with tap water. The test results showed thatdifferent waters significantly changed the consistency and compaction properties of high and low plasticityclays and that they did not cause a significant change in unconfined compression strength. Çoruh Basin reducedthe liquid limit of the CH and CL clays of the water by 33% and 20%, respectively. With the effect of the ÇoruhBasin, the optimum moisture content of the CH clay decreased by 41.2%, while the optimum moisture contentof the CL clay increased by 52.7% with the effect of the Fırat Basin.

A study on the effect of waste plastic strips in the stabilization of clay soil

The black cotton soilis the kind of soils whose size of size modifications together with the variation in moisture content material. They will have a conduct of expanding and contracting that is a severevulnerability to constructed building above them. The swelling behaviour of clay soil is existing in north Karnataka region. Thestudy demonstrates the results of an effortto strengthen and stabilize the clay soil with waste synthetic strips. The synthetic pieces being kept readyand integrated at three diverse blending proportions (0.5%, 1% and 1.5%) by mass of soil with various aspect ratios (8*8mm, 8*16mm, and8*24mm). The exploratory results demonstrated that there was obviously a development in the shear quality factors. The expanding and drying upwards conduct behaviour are additionally sensitively reduced. There was a reduction that is substantial the OMC and insignificant improvement in MDD. The maximum size of plastic (aspect ratio) and synthetic content that results in maximum outcome may be chosen based on the value for the selection parameter for a definite engineering work. Stabilizing black cotton soils with unwanted plastic containers at the same time solves the tasks of unsuitable plastic waste reutilizing that is presently a teething issue in many countries that are developing. The outcomes obtained from this investigation positively suggest that addition of this product in clay soils would succeed for ground enhancement in geotechnical engineering.

Strength Behaviour of Clay Soil Stabilized With Lime

Geotechnical Engineers are searching for new sustainable material, which can be suitable and effectively used to improves the engineering properties of clay soil. In this research lime is used as stabilizing material in the variable percentage of 1%,3%,5%,7%,9%,10%,12% and 15%. Lime is used as the admixture for soil stabilisation. Swelling pressure of the soil mixed with various proportions of lime such as 1, 7, 12 and 15%. Unconfined compression test, Plastic limit, Liquid limit, standard compaction proctor test, free swell index test and one-dimensional consolidation test are conducted to evaluate the clay soil strength in the laboratory. The experimental investigation results show that maximum strength improvement was achieved in the 12% lime mixed with clay soil and the strength improvement in the range of 300kPa. The results of the swelling test showed that applying lime to the soil decreases the swelling nature of clay soils.

Effect of forced carbonation on the behaviour of a magnesia-stabilised clay soil

ABSTRACT This paper presents an investigation into the behaviour of a clay soil stabilised with MgO under forced carbonation and comparison with conventional chemical stabilisation methods. The tests were conducted in two groups. In the first group the soil was mixed with 5, 10, 15 and 20% MgO or cement. Unconfined compressive strength (UCS) tests were performed on compacted samples from these mixtures at curing times of 7, 14 and 28 days. In the second group, samples prepared with different percents of MgO were subjected to CO2 under pressures of 0.5, 1.0 and 1.5 bar for periods of 4, 8, 12 and 24 h. The results showed that adding MgO increases the strength of the soil and, like other binders, the amount of increase in strength depends on the percent of MgO and curing time. It is also resulted that the effect of MgO is less than cement in increasing the strength. It was revealed that forced carbonation can facilitate the stabilisation of MgO-stabilised soil in a few hours compared with usual process that takes several days. XRD and SEM results showed that the gained strength is resulted from the interaction between the soil and the agents.

Geotechnical behaviour of clay soil mixed with rubber waste

In recent years, many engineering researchers have used waste rubbers for the purpose of soil improvement because of its geotechnical and environmental benefits. Rubber wastes extracted from tire waste and can exist in various forms. Three different forms of rubber including granular, fiber and chips were used in this study for evaluating the shear strength of the clay soil mixed with rubber wastes. Different tests including compaction, uniaxial, direct shear, and triaxial tests were employed for evaluating the geotechnical parameters of the mix, as well as microstructural studies by optical microscopy and binocular examination, for a better understanding of the underlying mechanisms. Rubber content, size, and form were the parameters investigated in this study. The results are suggestive of the increase in the strength and shear strain of the mixture by increasing the rubber size. According to the results, the strength of the mixture containing crumb rubber increased by 10–25% as compared to the mixture containing rubber powder under various confined stresses. Further, it was found that rubber fibers offered a higher strength than the other forms of rubber. The limited drop in the strength after the peak is also significant regarding the soil–rubber waste mixture. The separate study of strength under optimum moisture content and saturation conditions shows that this parameter demonstrates different behaviors under each of the conditions. The volume changes of the soil mix specimens are suggestive of a contraction in the mix. Given the reduced maximum dry density of the mix specimens and the favorable shear strength of the mix, using the waste rubber for various geotechnical engineering applications, such as filler material, is recommended.

Influence of Polypropylene Fibre (PF) Reinforcement on Mechanical Properties of Clay Soil

This study investigated the effects of polypropylene fibre (PF) reinforcement on the mechanical behaviour of clay soil. Using clay soil and polypropylene fibres from China’s Inner Mongolia and Hebei Provinces, respectively, a series of soil samples with 0%, 1.5%, 2.25%, and 3% PF content by soil weight were subjected to compaction, shear strength, consolidation, California bearing ratio, and microstructure analyses. The study results indicate improved compaction, shear strength, consolidation, and the bearing ratio of the PF-stabilised clay soil. As the PF content increased, its maximum dry density increased and its optimum moisture content decreased; its angle of internal friction increased and its cohesion coefficient decreased; and its void ratio, consolidation coefficient, and hydraulic conductivity all decreased. Comparing the unstabilised (0% PF) and stabilised (3% PF) clay soil, the void ratio, consolidation coefficient, and hydraulic conductivity decreased from 0.96 to 0.93, from 2.52 to 2.34 cm2/s, and from 1.12 to 1.02 cm/s, respectively. The optimum PF content was determined to be 3% by the weight of the soil, as this quantity resulted in the best improvement in soil properties.

Tensile response and fracturing process in moderate- and high-plasticity clays

Sinkholes in clay soils can be considered as the collapse of a soil layer previously bridging a void. Here, flexural deformation in the clay drives the formation of tensile cracks from the lowest surface of the layer and the consequent soil collapse is from crack propagation. Considering a simplified model of the sinkhole geometry, this paper aims to describe the tensile and fracture behaviour of clay soils with different plasticity indices. Speswhite kaolin, London, and Durham clays were tested using direct tensile and bending tests. Moderate- and high-plasticity clays showed a nonlinear fracture response with increasing moisture content, while low-plasticity clays demonstrated a linear response. Bending tests confirmed the importance of the moisture content while the plasticity index confirmed the difference in ductile or fragile collapse for fracture propagation. To assess the results, elasto-plastic fracture mechanics (EPFM) theory was applied to clays with appropriate modifications. The analysis demonstrated that EPFM theory provides a good baseline for predicting tensile fracture behaviour in clay soils, which can be extended in future research.

Performance of Eggshell Powder Addition to Clay Soil for Stabilization

The behavior of clay soil often becomes problematic for the building above it. One problem is its shrinking and swelling behavior which is affected by its water content, which also frequently influences the soil bearing of capacity in holding the load of the building above it. The powder from eggshell which abbreviated as ESP is a food industry waste that is high calcium and not often used for reprocessing. This experiment purposes is to know the effect of adding ESP as a stabilizing material in clay. Soil sample for laboratory testing was carried out from Cot Bagie Village, Blang Bintang, Aceh Besar District, and Aceh Province. From AASHTO classification system, the soil sample is A-7-5 (21) and from USCS system, is organic clay with high plasticity (OH). The percentages of ESP added are 0%, 3%, 6% and 9% of the dry weight of the clay for experiment on laboratory. The Atterberg Limit parameters commonly incline with ESP addition. Based on the standard Proctor test, the original soil has an Optimum Moisture Content (OMC) of 19.8% and a maximum dry unit weight (γd max) of 1.367 gr/cm3 . Overall, adding ESP to the clay sample increases the mechanical properties of soil compared to the sample without ESP. Thus, the use of ESP for stabilization in this experiment can improve the bearing capacity, so that it is beneficial for construction in the field.

Effect of human hair fiber reinforcement on shrinkage cracking potential of expansive clay

This paper presents the results of an experimental investigation carried out to study the shrinkage cracking behavior of clay soil under natural and reinforced conditions. Waste human hair fibers collected from barbershops are used as reinforcement along with other natural/synthetic fibers such as coir fibers and polypropylene fibers. Effect of reinforcement is studied on Atterberg’s limits of soil and shrinkage limits. The progressive crack propagation with drying is assessed using an image processing technique under unreinforced and reinforced conditions. The cracking potential of soil is interpreted in terms of crack intensity factor and crack reduction ratio. It is inferred from the results that the geometric and morphological characteristics of crack patterns were significantly altered by random inclusion of fibers. It is found that polypropylene fibers are most efficient in controlling the cracking potential, and human hair fibers are also found to perform practically comparable with polypropylene fibers. The percentage reduction in cracking with coir fibers is relatively less.