THE DRAINED RESIDUAL STRENGTH OF VOLCANICS DERIVED SOIL SAMPLED ON LANTAU ISLAND, HONGKONG

The knowledge of drained residual strength of cohesive soils is essential to the geotechnical engineer involved in handling landslide, slope stability, embankment design, and interaction of pile with foundation soil. This paper presents a review on measuring methods for residual strength and factors influencing residual strength of cohesive soils. Drained residual shear tests of volcanics derived soil sampled in Lantau Island of Hong Kong are performed on Bromhead ringshear apparatus. The results of investigations exhibit a nonlinear relation between residual strength and effective normal stress. A comparison of residual strength obtained by the single stage shearing with that by the multistage shearingindicates that the multistage shearing may give erroneous results due to lateralwall friction resulting from excessive settlement of soil sample during consolidation and shearing.