Shear wave propagation in residual soil–rigid inclusion mixtures

Abstract

Residual and tropical soils are particulate materialswith a wide range of particle sizes. Usually these geomaterials have a fine particle matrix containing dispersed rigid inclusions that affect theirmechanical behavior. This paper presents experimental results showing the influence of rigid inclusions on the shearwave velocity (Vs, or S-wave velocity) and small strain shearmodulus (Gmax) of a residual soil. Load tests under zero lateral displacementwereperformed with simultaneous measurements of Vs in mixtures of a residual soil with different amounts of steel spherical inclusions. The results show that specimens with a volume fraction of rigid inclusion equal to 70% have a Vs up to 250% higher than the same soil without inclusions when tested at close-to-zero effective vertical stress. This increase reduces to 150% when the effective vertical stress is over 400 kPa. Also, increasing the effective stress applied from0 to 400 kPa raises Vs 200% and 350% for high and lowvolumefractions of rigid inclusions,respectively. The results enabled the influence of both inclusion volume and effective stress on the Gmax of residual soils to be quantified.