Influence of Soil Suction on the Shear Strength of Unsaturated Soil

摘要

A laboratory investigation was conducted to assess the influence of suction onthe shear strength of unsaturated soil. Variables included the effects of compacting specimens of an expansive clay at different water contents, shearing specimen at various densities, and adding potassium chloride (KCl) to pore fluid of selected specimens. It was determined that shear strengths were dependent on the applied stress, density and water content of specimens at failure. A modified Mohr-Coulomb strength relationship was proposed to predict the shear strength of unsaturated soils. The effect of matrix suction was to increase the value of the cohesion intercept in this model. A method was proposed to characterize the influence of matrix suction on the shear strengths of unsaturated soils. It was determined that the magnitude of a suction depended on water content and the degree of saturation of the saturated specimens at failure while the effect of suction was a variable which was dependent upon the degree of saturation of the specimens. Elected specimens were treated with KCl prior to compaction. The effect of solute suction was to increase the value of the cohesion in the modified Mohr-Coulomb strength relationship. Keywords: Soil mechanics; Saturated soils; Soil stabilization; Soils/compacting/expansion; Shear strength; Pore pressure; Clay/montmorillonite; Potassium chloride; Soil tests; Moisture content; Cohesive soils. (mm)