Advanced Direct Shear Testing for Collapsible Soils with Water Content and Matric Suction Measurement

At natural, in-situ water content, collapsible soils have high strength and relatively high void-ratio with low compressibility. These soils could easily collapse when wet. If the differential deformations and slope stability effects have been neglected in the design and construction processes, they could cause damage to constructions. Therefore, the identification of collapsible soils with estimation of the collapse potential and shear strength become major components in appropriate engineering for these moisture-sensitive soil sites. To deal with shear strength of unsaturated soil or collapsible soil, the direct shear box apparatus for measuring in water content with matric suction must be modified. The electrical sensors for water content measurement are installed near the shear plane. Due to low friction material, Teflon sheets are then used as a spacer to control the water content of the specimen during testing.