Effect Of Suction On Dynamic Properties Of Unsaturated Soils At Mid- To High-shear Strain Amplitudes

Abstract

This paper presents the results from an experimental study that has been designed to assess the effect of the suction and net mean stress on the dynamic properties of poorly graded sand with silt subjected to small- to mid-shear strains. The practical implication of this study includes determining the effect on soil stiffness properties of increased matric suction (transpiration of water) at different net mean stresses (or depths) in the field. The engineering analysis of earth structures subjected to static and non-static loading under unsaturated conditions requires knowing the relevant parameters of the soil, such as shear wave velocity, shear modulus, and material damping. The traditional soil mechanics and geotechnical engineering have generally focused on soil extreme conditions, that is, completely dry or saturated state of soil; thus, these branches of soil mechanics present shortcomings to estimate the true soil strength and stiffness, and its behavior at small- to mid-shear strains, under partially saturated conditions. In the last years, additional efforts have been made to gain a better understanding of partially saturated soil behavior by using field and laboratory based measurements of soil suction. However, these efforts have not thoroughly covered the dynamic response of partially saturated soils at small- to mid-shear strain amplitudes. This work intends to study the dynamic response of unsaturated soils, particularly and the effect of varying matric suction and net mean stress on shear modulus, material damping and threshold strain.