Tensile strength of unsaturated coarse and fine-grained soils

Abstract

Soils at the ground surface experience multiple cycles of drying and wetting. On drying, the soils experience shrinkage and cracks may appear. The development of cracks depends on the tensile strength of the soil. Such cracks increases the permeability of the soil and can cause slopes and earth structures to fail due to rainfall. Several tensile strength models have been proposed for unsaturated soils considering the effect of matric suction. However, the tensile strength models proposed are for either cohesionless (coarse-grained) or clayey (fine-grained) soils. The tensile strength models were shown to be different in their definition of suction stress and the presence or absence of a cohesion term. As tensile strength data of fine-grained soils with the same soil structure and soil-water characteristic curve data are lacking in the literature, Brazilian tensile tests and SWCC tests were conducted on compacted fine-grained soils from two residual soil formations. The test data highlighted the problem in the friction angle used in existing tensile strength models. Using a general form of the suction stress and the extended Mohr-Coulomb criterion with the Brazilian test Mohr circle, a new tensile strength model applicable to both coarse-grained and fine-grained soils was proposed. The proposed model was shown to perform better than existing models using independent data.

A Study on Uniaxial Compressive Strength and Ultrasonic Non-Destructive Analysis of Fine-Grained Soil in Seasonally Frozen Regions

“…High clay content in a fine-grained soil tends to shrink and expand as the volume of water changes. The change in volume can lead to structural problems for buildings hence posing critical threats to geotechnical engineers [1][2]. Due to the variation of mechanical properties exhibited by these soils, frost susceptibility, excessive compression, high swelling potential, low strength, and collapse behavior are examples of possible structural damages to be encountered [3][4][5].…”