Abstract：For investigation on the characteristics of shear deformation and strength of layered salt rocks in Yunying Salt Mine，Hubei Province，direct shear tests on three types of rocks are carried out. It is shown that the curves of shear stress vs. displacement of salt rock，anhydrite and layered salt rock are similar：during the beginning stage of shear loading，the slope coefficients are small，the shear displacement increasing fast while the shear stress increasing slowly；when the shear stresses reach a certain value，the increase of shear displacement slows down，and the slope coefficients get larger；the increase of shear displacement becomes fast again prior to shear stress reaching peak value；after peak point，strain softening appears，the shear stresses decreasing slowly and reaching residual strength finally. The test results also show that the shear strength of layered salt rocks is close to or even slightly higher than that of salt rock and anhydrite：cohesive strength MPa，and frictional angle 45.9°. This indicates that the interfaces between salt rock and anhydrite are not weak as expected. The strong interface property of layered salt rocks will guarantee the sealability and stability of salt caverns，and benefit the energy(oil and gas) storage in layered salt rocks formation in depth.
