Lateral Swelling Pressure Research Articles

At-rest lateral earth pressure of compacted expansive soils: Experimental investigations and prediction approach

This paper presents experimental studies on a compacted expansive soil, from Nanyang, China for investigating the at-rest lateral earth pressure σL of expansive soils. The key studies include (i) relationships between the σL and the vertical stress σV during soaking and consolidation, (ii) the influences of initial dry density ρd0 and moisture content w0 on the vertical and lateral swelling pressures at no swelling strain (i.e. σV0 and σL0), and (iii) evolution of the σL during five long-term wetting-drying cycles. Experimental results demonstrated that the post-soaking σL-σV relationships are piecewise linear and their slopes in the passive state (σL > σV) and active state (σL < σV) are similar to that of the consolidation σL-σV relationships in the normal- and over-consolidated states, respectively. The soaking σL-σV relationships converge to the consolidation σL-σV relationships at a threshold σV where the interparticle swelling is restrained. The σL0 and σV0 increase monotonically with ρd0; however, they show increasing-then-decreasing trends with the w0. The extent of compaction-induced swelling anisotropy, which is evaluated by σL0/σV0, reduces with an increase in the compaction energy and molding water content. The σL reduces over moisture cycles and the stress relaxation in the σL during soaking is observed. An approach was developed to predict the at-rest soaking σL-σV relationships, which requires conventional consolidation and shear strength properties and one measurement of the σL-σV relationships during soaking. The proposed approach was validated using the results of three different expansive soils available in the literature.

Laboratory Investigation of Lateral Swelling Pressure of Nanning Grey-White Expansive Soil

Laboratory Investigation of Lateral Swelling Pressure of Nanning Grey-White Expansive Soil

Model for Lateral Swelling Pressure in Unsaturated Expansive Soils

AbstractUnsaturated expansive soils annually cause major economic losses and structural damages to foundations and earthen structures, primarily due to exhibiting large amounts of swelling and shri...

A Framework for Interpreting Lateral Swelling Pressure in Unsaturated Expansive Soils

Lateral swelling pressure (LSP) develops when expansive soil volume increment associated with water infiltration is restrained in a confined domain, for example, due to construction of civil infrastructure. In this paper, initially a flowchart is developed to highlight various key factors that influence the LSP mobilization according to lab and field studies collected from previous literature studies. Then extending unsaturated soil mechanics, a theoretical framework is proposed for illustrating the LSP mobilization in the field against retaining structures and pile foundations under different boundary conditions, respectively. An example problem for a basement wall and a pile foundation constructed in a typical expansive soil from Regina, Canada, is presented to illustrate the proposed theoretical framework. The framework and corresponding analysis presented in this paper can facilitate to provide rational designs of geotechnical infrastructures in expansive soils.

Simulation of behaviour of swelling soil supported by a retaining wall

The lateral swelling pressure (LSP) and vertical swelling of a highly expansive soil supported by a retaining wall was studied. Experimental work was conducted by designing a physical laboratory model with dimensions of 900 × 600 mm in plan and 950 mm in height. The finite element method was used to simulate the retaining wall supporting highly expansive soil in saturated and unsaturated conditions using GeoStudio 2007. Verification of the physical model showed that the LSP increased linearly with the depth of the wall up to the maximum value of about 165 kPa at a depth of 0.6 m. Predictions during saturation and loading stages showed that the quantitative predictions were within the measurement accuracy. Numerical predictions of the LSP and vertical swelling were compatible with the experimental results. The vertical swelling and percentage decrease in swelling decreased with the depth of the soil. The percentage decrease in vertical swelling was 95.0% at 34 days and a depth of 0.6 m. The rate of swelling decreased with an increase in soil depth and the time required to reach an equilibrium state of swelling decreased linearly with soil depth.

Experimental Study on Swelling Behavior and Its Anisotropic Evaluation of Unsaturated Expansive Soil

Evaluation of swelling behavior is important for designing structures in expansive soils areas, especially for highway that the swelling pressure generated upon pavement and retaining structures in both vertical and horizontal directions due to infiltration. In this study, modification was made on unsaturated consolidation oedometer to provide synchronized measurement of vertical swelling strain (VSS) and lateral pressure (LP) of expansive soil under constant net normal stress and controlled matric suction. Vertical swelling (VS) test and lateral swelling (LS) test were conducted to investigate the anisotropic swelling behavior. The influence of mean net stress and net stress ratio on VSS was investigated, and the anisotropic swelling behavior of unsaturated expansive soil was characterized using anisotropic swelling ratio. The results show that the VSS nonlinearly decreased as the mean net stress increased and increased as the net stress ratio increased. The expansive soil would rapidly enter the passive state due to lateral swelling pressure under relatively low surcharge, with major principal axis rotating from vertical direction to lateral direction, which advances the possibility of passive failure for light retaining structures. The anisotropic swelling behavior objectively exists and varies with matric suction and net normal stress, which should not be ignored for engineering application.

Swelling characteristics of andesite foundation induced by water immersion and their influence on ballastless track subgrade

To study the mechanical and deformation characteristics of ballastless track subgrade filled with micro-expansion fillers in a water-immersed environment, a physical model of ballastless track subgrade was constructed on a 1:2 scale with expansive andesite fillers. A water immersion test was carried out to model the soaking of the expansive soil foundation caused by rising groundwater. The swelling behaviors of the foundation and their influences upon the mechanics and deformations of the subgrade were analyzed. The lateral swelling pressure of the foundation and the heave of the subgrade obviously increased due to the water immersion, and the values were closely related to the overlying load and lateral restraint. The heave deformation of the double-line ballastless track subgrade showed significant nonuniformity along the lateral direction, causing the track slab to incline with a maximum inclination angle of 1.55×10-3 deg. The heave of the foundation caused a heave in subgrade, but this transferred heave was significantly attenuated. The attenuation rate of the heave at the midline of the track slab was up to 13.38%. The attenuation characteristic can be fully utilized for the anti-heave deformation measures of railway subgrade in expansive soil areas.

Experimental Evaluation of Lateral Swelling Pressure of Expansive Soil Fill behind a Retaining Wall

AbstractLateral swelling pressure (LSP) of expansive soils included in the total lateral pressure (TLP) often results in instability and even sliding failure of retaining walls. In this study, a mo...

Swelling behavior of compacted bentonite-sand mixture during water infiltration

A laboratory-based water infiltration test was conducted with compacted Calcigel bentonite-sand mixture (50:50) at room temperature to mimic the transient hydration of a backfill material in nuclear waste repository conditions. The test was performed with an innovative column-type experimental device, which facilitated the continuous and non-destructive measurements of temperature, relative humidity, water content and total stresses in both axial and lateral direction at various preselected locations along the height of soil sample. The effect of groundwater geochemistry on the bentonite hydration process was not considered in this study. The distilled water was supplied from the bottom-end under 15-kPa hydration pressure for a period of 349 days to mimic the water ingress from the host rock. The test results highlighted the hydration-induced heterogeneity in the material and its effect on the lateral swelling pressure development along the height of soil sample. The axial swelling pressure measurements revealed the factors, which affect the stress-transfer mechanism between both the ends. The simultaneous measurements of relative humidity and water content indicated the porosity redistribution close to the hydration-end during the test.

Prediction of lateral swelling pressure behind retaining structure with expansive soil as backfill

Lateral swelling pressure (LSP) develops in expansive soil when the volume expansion associated with water infiltration is restrained in the horizontal direction due to a rigid infrastructure. Various types of testing techniques, used to determine the LSP from both laboratory and field studies, are critically reviewed by focusing on two key factors, namely, the boundary conditions and the saturation path. Most testing techniques are capable of reasonably simulating the stress state of a soil element behind a retaining structure by applying a fixed boundary condition in the horizontal direction and a stress boundary condition in the vertical direction. However, they are only used to determine the LSP following a simple path, which is from an initially unsaturated state to a fully saturated state. In other words, these tests fail to provide information on the variation in LSP with respect to changes in the degree of saturation, the water content or the matric suction during the infiltration process. Furthermore, the literature review suggests that a reliable model for the prediction of the LSP during the infiltration process is not available. For this reason, a model is proposed in this paper to estimate the lateral earth pressure (LEP) considering the variation in LSP behind fixed rigid retaining structures with respect to the matric suction during the infiltration process. The proposed model is simple and only requires information, which includes the soil water characteristic curve (SWCC) and a limited number of soil properties. Data from one large-scale model test and two field case studies from published literature are used to illustrate and verify the proposed model. Reasonable comparisons are made between the predictions and the measured data. The proposed model will be a valuable tool for use in conventional engineering practice for the quick prediction of the increasing LEP behind retaining structures with expansive soils as backfill due to the development of LSP associated with water infiltration.

Comparison of three inclusions in reducing lateral swelling pressure of expansive soils

Lateral swelling pressures of expansive soils impose significant threats to the stability and safety of retaining structures. Placing a layer of compressible material, such as cohesive non-swelling soil (CNS), expanded polystyrene (EPS) geofoam or cohesionless soil (such as sand), between the retaining structure and the expansive soil can effectively reduce the lateral swelling pressure acting on the retaining structure. The work presented in this paper compares the efficiency of CNS, EPS and sand inclusions in reducing the lateral swelling pressure of a natural expansive clay. A special consolidometer was used to measure the lateral swelling pressure of expansive soil samples with and without inclusions under constant-volume condition, upon saturation. An analytical approach was used to interpret the efficiency of CNS, EPS and sand inclusions in reducing the lateral swelling pressure. It is found that (i) the efficiency of EPS inclusions is much higher than that of CNS and sand inclusions and (ii) sand is more effective than CNS in reducing the lateral swelling pressure at the same degree of compaction. It is suggested that EPS is preferred, the efficiency of sand is limited, and highly compacted CNS is unfavorable in reducing lateral swelling pressures.

Discussion of “Influence of Lateral Swelling Pressure on the Geotechnical Infrastructure in Expansive Soils” by Yunlong Liu and Sai K. Vanapalli

Discussion of “Influence of Lateral Swelling Pressure on the Geotechnical Infrastructure in Expansive Soils” by Yunlong Liu and Sai K. Vanapalli

Closure to “Influence of Lateral Swelling Pressure on the Geotechnical Infrastructure in Expansive Soils” by Yunlong Liu and Sai K. Vanapalli

Closure to “Influence of Lateral Swelling Pressure on the Geotechnical Infrastructure in Expansive Soils” by Yunlong Liu and Sai K. Vanapalli

Deformation characteristics and stress responses of cement-treated expansive clay under confined one-dimensional swelling

This study presents an investigation of the effects of cement addition to expansive clay on its deformation characteristics and stress responses during swelling. The effects were evaluated by focusing on the unconfined compressive strength, swelling-shrinkage strains under various conditions, and the lateral coefficient of earth pressure during one-dimensional deformation for artificial mixtures of two different clays at three different ratios. The clays used in this study were a Na-montmorillonite bentonite and a non-expansive Bangkok clay, mixed at different proportions to simulate naturally encountered expansive clays with different degrees of swelling potential. The experimental programme involved unconfined compression, areal shrinkage strain by unconfined drying, vertical free swelling strain, and confined swelling pressure tests. The experimental results show that the cement addition led to marked decreases in the areal shrinkage strain and vertical free swelling strain in addition to the obvious improvement of strength and stiffness of soils. The confined swelling pressure test results indicated that the cement had a greater effect in reducing vertical swelling pressure than the lateral swelling pressure of the soils during one-dimensional swelling. The measured lateral coefficient of earth pressure and stress paths of untreated and cement-treated soils and their engineering implications are discussed.

Influence of Lateral Swelling Pressure on the Geotechnical Infrastructure in Expansive Soils

AbstractLateral swelling pressure (LSP) can pose significant threats to the safety and stability of the geo-infrastructure. For this reason, it is necessary to take into account the influence of LS...

Infiltration Column for Studying the Lateral Swell Behavior of Expansive Clay

Abstract Infiltration column is usually used to investigate the hydro-mechanical processes in unsaturated expansive clay. In this test, the moisture transfer is often monitored along the column during water infiltration using suction or water content probes. Nevertheless, the lateral swelling pressure developed is rarely considered. This paper describes an infiltration column for studying the lateral swell behavior of expansive clay. The column consists of a rigid cell ensuring the constant-volume condition and a hydraulic system enabling the water intake of the hosted sample. It is equipped with three types of sensors: pressure sensors, force transducers, and displacement transducers to, respectively, monitor the radial and axial swelling pressure of the sample at different positions and to check whether any axial displacement is taking place. A detailed description of the different parts of the cell is first presented. Second, analysis on the results of a test on a compacted bentonite/sand mixture allows the pertinence of such a device to be evaluated.

Experimental study on the inclusion of soilbags in retaining walls constructed in expansive soils

In this study, the reduction of lateral swelling pressure on retaining walls in expansive soils is investigated. Swelling pressures can develop if the soil is not allowed to swell freely. When some soil expansion is allowed, the swelling pressure may decrease considerably relative to conditions under which no expansion is allowed. This study introduces a new method for reducing the lateral swelling pressure on retaining walls by using the inclusion of soilbags. A modeling experiment was conducted to examine the roles of the inclusion of soilbags in accommodating soil expansion and reducing the lateral swelling pressure on adjacent retaining walls. Two artificial rainfall events were created during one month of monitoring. The results showed that the inclusion of soilbags were more permeable and enhanced drainage, which shortened the duration of the delayed response to lateral swelling pressure and kept the lateral swelling pressure steady when it reached its peak value during the rainfall period. The soil expansion was restricted in the bags during rainfall infiltration, which resulted in a reduction in the swelling potential of the soilbags. The lateral compressibility of the wetted soilbags was relatively high, which allowed for lateral expansion of the soil, especially under a small vertical load. These findings indicate that the lateral swelling pressure can be effectively reduced by using the inclusion of soilbags.

FIELD STUDY OF THE DISTRIBUTION OF LATERAL SWELLING PRESSURE OF EXPANSIVE SOIL ON RETAINING STRUCTURE

The important requirements for civil engineer are economic and technical in the field and thisappears in fill work. The civil engineer needs a suitable soil for fill works, so the expansive soil isstudied as one of the possible solution.For this research the physical, mechanical and field tests are performed. The purpose of the presentpaper is examining the distribution of lateral swelling pressure developed in clay soils on retainingwalls after adding water and to predict the values and shape of pressures distribution for designpurposes.So, five cells of strain gauges were prepared, the distance between them equals 50cm. and they werefixed at wooden sheet on bedroom's wall in one of Assiut el gadida city projects.Prediction of lateral earth pressures has been a problem to civil engineers for a long time. The firstrational approach by which lateral earth pressures could be estimated was simple and practical, andthey have come to be known as the classical methods of prediction of lateral earth pressure.The behaviour of soil is swelling after adding water then affects on retaining structures. The effectof soil is depending on many factors like water content, depth, the type and quantity of mineral insoil composition, the time, … etc.The results of this research give a good knowledge about the value and the distribution of lateralswelling pressure, and the results showed that the swelling pressure on retaining structure increasesby increasing the water content and montmorillonite minerals content in soil. Then, the resultsenable the civil engineers to attain safe and suitable design for retaining structure withoutengineering problems...

EXPERIMENTAL STUDY ON THE EFFECT OF LATERAL SWELLING PRESSURE OF EXPANSIVE SOIL ON RETAINING STRUCTURE

The lateral swelling of expansive soil on retaining structures investigation is very important for civil engineer .The used soil in this research is obtained from Assiut el gadida city projects; Assiut, Egypt .It contains SiO2, AL2O3 and Fe2O3 as main oxides. For this research the physical and mechanical properties of soil are obtained, the purpose of the present paper is examining the phenomenon of lateral swelling pressure developed in clay soils after adding water to it. Also suggest useful means to predict the magnitude and distribution of those pressures for use in retaining structure design. The behaviour of soil is swelling after adding water then affects on retaining structure. The effect of soil is depending on many factors as water content, depth, the type and quantity of mineral in soil composition, the time… etc. The results showed that the swelling pressure on retaining structure increases by increasing the depth at soil up to depth equals 60cm and decreases beyond that. Also, the maximum swelling pressure occurred after 48 hours measured from adding water to expansive soil.

Prediction of swelling pressures of expansive soils using artificial neural networks

Swelling behavior of expansive soil is a complicated phenomenon. In order to cope with the complications in describing the swelling behavior of expansive soil, researchers developed alternative approaches. In this paper, the prediction model of transmitted lateral swelling pressure, and vertical swelling pressures on a retaining structure was developed using artificial neural network (ANN) approach. In the first stage of this study, the lateral and vertical swelling pressures were measured with different thicknesses of expanded polystyrene (EPS) geofoam placed between one of the vertical walls of the steel testing box and the expansive soil. Then, artificial neural network was trained using these pressures for prediction transmitted lateral swelling pressure, and vertical swelling pressures on a retaining structure. Results obtained from this study showed that neural network-based prediction models could satisfactorily be used in obtaining the swelling pressures of the expansive soils.