Kiyoshi Namikawa

Soil failure under undrained quasi-static and high speed triaxial compression test

Abstract Experiments were conducted in unsaturated silty loam and sandy loam soils under undrained conditions. Soil failure under quasi-static and high speed triaxial compression were studied. The amount of energy used in breaking soil specimens was found to be a function of soil moisture content. During undrained quasi-static triaxial compression tests, two cases of brittle failure, a general shear failure and a fragmentation were observed. The test soil specimen broke more by fragmentation than by general shear failure. During undrained high speed triaxial compression tests, the energy use for breaking the soil specimen increased with increase in loading speed up to a certain critical speed range of 4.5–5 m/s, and then it decreased. Two types of soil failure, brittle failure and plastic flow, which were a function of the loading speed, were noticed. At lower speed, dilation of shearing along a slip plane was observed. However, at higher speed, barreling of the cylindrical specimen with top and bottom conical shaped wedges, or only a single wedge with a small crack or fluidization, was observed.