Static and Cyclic Direct Shear Tests on Carbonate Sands

Abstract This paper examines the static and cyclic behavior of different types of carbonate sediments and one type of silica sand under direct shear test conditions. For both static and cyclic loading, the effects of interface surface roughness, overburden pressure, void ratio, size and shape of grains, and saturation are studied. It is found that the static shear resistance is influenced by most of these factors and that the cyclic behavior depends significantly on the number of cycles and the cyclic displacement amplitude. The amount of crushing caused by cyclic loading is found to depend strongly on particle shape and grading characteristics. The results of the static tests can supply useful information about the strength parameters (δ and ϕ), which are important in assessing skin friction for the design of pile foundations. The cyclic test results provide useful indications of the likelihood of degradation of pile skin friction under cyclic loading. The larger the volume change under cyclic loading, the greater is the likely amount of degradation.