Effects of Post-compaction Residual Lateral Stress and Electrolyte Concentration on Swelling Pressures of a Compacted Bentonite

Tripathy, Snehasis; Bag, Ramakrishna; Thomas, Hywel Rhys

doi:10.1007/s10706-014-9754-7

Cited by 29 publications

(4 citation statements)

References 41 publications

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“…The equilibration period was considered to allow redistribution of water content and relative humidity (suction) within the sample. Studies in the past have shown that compacted expansive soils exhibit stresses due to the relaxation of the static compaction stress and particle rearrangement (Subba Rao and Tripathy 2003;Tripathy, Bag, and Thomas 2014). Therefore, changes in the stress were monitored during the equilibration period.…”

Section: Test With Compacted Bentonite-sand Mixturementioning

confidence: 99%

“…Geotechnical Testing Journal (Tripathy, Bag, and Thomas 2014) occurred with time at a constant water content, leading to an increase in the axial stress in the direction opposite to that of the compaction stress which, in turn, caused a reduction in the lateral stress. The other factors that may contribute to the changes in axial and radial stresses are the particle rearrangement with time at a constant water content (Subba Rao and Tripathy 2003), redistribution of water content following the compaction process, and redistribution of stress due to the presence of voids at the interfaces between the compacted samples and between the sample, the sensors, and the pressure transducers.…”

Section: (A) ( B)mentioning

confidence: 99%

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A Column-Type Experimental Device for Investigating Coupled Thermo-Hydro-Mechanical Behavior of Expansive Soils

et al. 2021

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This paper presents a newly designed column-type experimental device for investigating the coupled thermo-hydro-mechanical behavior of expansive soils. Sensors and monitoring instruments facilitated continuous and nondestructive measurements of temperature, relative humidity, water content, and total stresses in both axial and lateral directions at various preselected locations of the device. The design features and calibration of specific accessories are presented. System implementation and validation tests were performed to examine the performance of the device at an elevated temperature. In the context of underground storage of nuclear waste, a test was performed with a compacted Calcigel bentonite-sand mixture (50:50) to investigate the thermo-hydro-mechanical behavior of the material under an applied temperature gradient involving temperatures of 80°C and 20°C at the opposite ends of the sample. The test results highlighted the key features of temperature-driven processes in unsaturated compacted porous media. Thermal loading caused changes in the water content and relative humidity within the sample. During the temperature equilibration period, the thermal dilation phenomenon in the regions closer to the heat source was found to be responsible for the development of axial and lateral stresses in the sample. A longer duration of thermal loading caused volumetric shrinkage of the material, which in turn affected the magnitudes of both axial and lateral stresses.

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Section: Test With Compacted Bentonite-sand Mixturementioning

confidence: 99%

Section: (A) ( B)mentioning

confidence: 99%

A Column-Type Experimental Device for Investigating Coupled Thermo-Hydro-Mechanical Behavior of Expansive Soils

et al. 2021

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“…As an impermeable material in engineering application, vertical swelling strain is an important factor for MB. The vertical swelling strain of MB represents the corresponding vertical load causing expansion to the same strain under the same load [43]. Hence, the relationship between vertical swelling strain of MB specimen and vertical pressure levels could express the constitutive relationship between vertical swelling strain and vertical swelling stress.…”

Section: Effect Of Vertical Pressurementioning

confidence: 99%

Swelling Capacity and Hydraulic Conductivity of Polymer-Modified Bentonite under Saline Water Conditions

Liu

et al. 2018

Applied Sciences

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Bentonite is widely used as a waterproof material in civil engineering. The swelling capacity and impermeability will be reduced in saline water conditions. A polymer-modified bentonite was used in this study, and the swelling characteristic and hydraulic conductivity in saline water were investigated. Results show that: the modified bentonite (MB) has good swelling characteristics and low permeability in saline water conditions; the unload swelling strain of MB in saline water conditions increased with rising swelling time; the final unload swelling strain of MB decreased with the increase of vertical pressure and increased with increasing initial dry density; and, as the swelling time increased, the swelling pressure increased rapidly at first and then decreased. Based on experimental results, this study obtained a linear relationship between the ratio of time to unload swelling strain and swelling time, a formula for load swelling strain that was related to initial dry density and vertical pressure, a linear relationship between the ratio of time to swelling pressure and swelling time, and an exponential relationship between swelling pressure and initial dry density. The MB can be used as a waterproof material in seepage-prone applications under saline environmental conditions in civil engineering works.

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“…The salinity of groundwater has a strong inhibitory effect on swelling potential due to the influence on the diffuse double layer (DDL) (Yong & Mohamed, 1992; Tripathy et al ., 2004; Siddiqua et al ., 2011; Liu, 2013; Tripathy, 2014). When the ionic strength increases, the thickness of the DDL and the net repulsive stress between bentonite particles decrease, leading to a decrease in the swelling potential (Schanz & Tripathy, 2009; Tripathy et al ., 2014; Xu et al ., 2014). The DDL model was valid in the cases of osmotic swelling when compacted bentonites were brought into contact with dilute salt solutions (Liu, 2013; Xiang et al ., 2014).…”

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confidence: 99%

Prediction for swelling deformation of fractal-textured bentonite and its sand mixtures in salt solution

Xiang

et al. 2019

Clay miner.

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Swelling deformation tests of Kunigel bentonite and its sand mixtures were performed in distilled water and NaCl solution. The salinity of NaCl solution has a significant impact on the swelling properties of bentonite, but not on its surface structure. The surface structure was characterized using the fractal dimension Ds. Based on the fractal dimension, a unique curve of the em–pe relationship (em is the void ratio of montmorillonite and pe is the effective stress) at full saturation was introduced to express the swelling deformation of bentonite–sand mixtures. In mixtures with a large bentonite content, the swelling deformation always followed the em–pe relationship. In mixtures with a small bentonite content, when the effective stress reached a threshold, the void ratio of montmorillonite em deviated from the unique em–pe curve due to the appearance of a sand skeleton. The threshold of vertical pressure for mixtures in different solutions and the maximum swelling strains were estimated using the em–pe relationship. The good agreement between estimates and experimental data suggest that the em–pe relationship might be an alternative method for predicting the swelling deformation of bentonite–sand mixtures in salt solution.

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Effects of Post-compaction Residual Lateral Stress and Electrolyte Concentration on Swelling Pressures of a Compacted Bentonite

Cited by 29 publications

References 41 publications

A Column-Type Experimental Device for Investigating Coupled Thermo-Hydro-Mechanical Behavior of Expansive Soils

A Column-Type Experimental Device for Investigating Coupled Thermo-Hydro-Mechanical Behavior of Expansive Soils

Swelling Capacity and Hydraulic Conductivity of Polymer-Modified Bentonite under Saline Water Conditions

Prediction for swelling deformation of fractal-textured bentonite and its sand mixtures in salt solution

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