Matric suction and stiffness measurement on soil containing fines at low stress state

Abstract

Matric suction significantly attributes on both strength and stiffness of the geomaterials. Earthen structures constructed by soil containing fines are profoundly found to be at an unsaturated condition. The unsaturated soil is often subjected remarkably significant and continuous changes in matric suction with variation in moisture content. This study focuses on an experimental investigation of Matric suction variation and its attribution on stiffness by means of elastic wave measurement on fine sand (Toyoura sand) with two types of fines; kaolin and non-plastic silt as well as natural soil containing fines(Edosaki sand). The small-scale triaxial apparatus equipped with disk transducer for measuring elastic wave and pressure membrane technique for evaluating matric suction is employed. A cylicndrical specimen is prepared by sandy soil with several amounts of fines and subjected to change in moisture content by injecting water inside the specimen. Both compressional and shear waves velocities are measured in conjunction with an associated matric suction at low stress level that replicates the soil behavior of the shallow depth. This investigation reveals that the presence of fines in soil appears to play an important role in mechanical behavior of sandy soil. The small strain stiffness as well as dynamic properties seems to be affected by the moisture condition in the soil.