Effects of coarse-grained material on hydraulic properties and shear strength of top soil

Sidewalk failures associated with top soil of low shear strength are a common problem in urban areas. Mixing top soil with granite chips can be used to increase its permeability and shear strength. The effects of mixing granite chips with top soils on the hydraulic properties and shear strength under saturated and unsaturated conditions were investigated in this study. The results showed that the mixing top soils with granite chips caused changes in several key parameters of the soil–water characteristic curve (e.g., the air-entry value, the residual matric suction, and the residual volumetric water content) and the unsaturated permeability of the top soils. The saturated permeability and shear strength of the soil mixture increased with increasing content of granite chips.