Calcareous sands generally consist of marine sediments. Compared to the terrigenous sands

they tend to crush easily under load

and the mechanical character will change subsequently. Laboratory triaxial shear tests under different confining pressures and strains on calcareous sands which are taken from the South China Sea are presented. And the particle size of the sample is sieved before and after tests. The results show that the particle breakage of sand is very serious under triaxial shear. And the crushability of the sand is quantified by using Hardin model. The relationship among confining pressures

shear strain and particle breakage is also discussed.