Shear strength characteristics of a sand clay liner

Muawia Dafalla,Abdullah Almajed,Mosleh Al-Shamrani,Tamer Elkady,Abdullah Shaker

doi:10.1038/s41598-020-75188-1

Abstract

This study investigated shear strength behaviour of compacted sand–clay mixtures used as liners, with 10%, 20%, and 30% clay contents. A natural high-plasticity and highly expansive clay found in the eastern province of Saudi Arabia was used. A series of consolidated undrained triaxial tests and pore water pressure measurements of saturated samples with various clay contents and confining pressures was conducted using a computer-controlled Bishop and Wesley triaxial cell. The unit was equipped with pressure volume controllers and a pressure transducer for measuring sample volume changes and excess pore water pressure. The experimental test results indicate that clay content and confining pressure significantly affect stress strain response curves, pore water pressure generation curves, and steady-state shear strength. Sand–clay mixtures with clay content less than 10% showed a tendency toward contractive behaviour. The failure line slope increased in accordance with clay content increase. The deviator stress versus axial strain of saturated sand–clay mixtures indicated a hyperbolic trend. The stress ratio versus axial strain representation was more informative for the shear strength behaviour assessment. Clay content did not significantly affect critical-state friction angle. Scanning electron microscope images of the sand-clay mixtures with different clay contents are presented.

Highlights

This study investigated shear strength behaviour of compacted sand–clay mixtures used as liners, with 10%, 20%, and 30% clay contents
A reverse trend was observed at failure for the clay contents greater than 10%, with the deviator stress decreasing in accordance with an increase in the clay content
The undrained behaviour of the sand–clay mixtures is best interpreted using the stress ratio versus axial strain representation because the effective stress ratio at failure is a function of the pore water pressure measured during the undrained testing, whereas the deviator stress is not

Summary

Introduction

This study investigated shear strength behaviour of compacted sand–clay mixtures used as liners, with 10%, 20%, and 30% clay contents. Confining pressure on the shear strength and stress–strain behaviour of the compacted sand and bentonite mixtures.

Results

Conclusion