Abstract: The salt layer in the deep stratum is usually used to form cavern for natural gas storage. The behavior of dilation of salt rock is the important criterion for the safety of storage. In this paper, the volumetric dilation behavior and the dilation angle model of salt rock with mudstone is analyzed from the compressed test under different confining pressures. Experimental results show that strain-hardening law and obvious volumetric dilation during the test. From Mohr-Coulomb plastic potential function, the dilation angle of samples increases with the increase of plastic shear strain. And the dilation angle can approach 7o-10oat last. Finally, the dilation angle model with plastic shear strain and confining pressure is constructed. The dilation angle model that simulates perfectly the volumetric strain of salt rock with mudstone is verified by the numerical simulation.

Key words: salt rock with mudstone, natural gas storage, rock dilation, dilation angle