Abstract: Using large-scale shearing device, isotropically consolidated-drained triaxial test under different
confining pressures are performed for relative density overburden material of Shuangjiangkou earth dam.
The influence of density on strength and deformation properties of sand-grained material is studied. The
results show that the linear strength index nonlinear strength index  and  all increase with the relative density
 increases, and the increases in nonlinear strength index  and  are linear. The volume
strain value of sand-grained material decrease with the relative density increases and the dilatancy of
sand-grained material increase with the relative density increases. The secant modulus and the failure
Poisson ratio of coarse-grained soil both increase with the relative density of sand-grained material increases.
According to the test data, a formula for relation of the secant modulus of sand-grained material and the
relative density Dr and confining pressure is obtained, And meanwhile, a relation formula for the failure
poisson ratio ?1f and the relative density Dr and confining pressure ?3 is also obtained under specific
confining pressure.