Experimental investigation of mechanical behavior of bedded rock salt containing inclined interlayer

• We conducted matrix-test of uniaxial and triaxial compression tests on composite rock salt containing inclined interlayer.
• We observed and revealed the fracture geometries in different locations of the interlayer.
• We indicated the different effect of interlayer thickness to the deformation and fracture properties.
• We reveal the influence of inclined interlayer to the tightness and stability of the caverns.

Uniaxial and triaxial compression tests have been carried out on specimens of rock salt, interlayers, and composite rock salt (containing inclined interlayers). In combination with failure mechanism analysis of the stratified rock structures, the variation and impact factors of bonding stresses between the layers have been investigated, and the fracture properties and failure mechanisms of inclined bedded rock salt have been revealed. The research demonstrated that the inclined interlayer influences the deformation and fracture properties of rock salt. Due to the composite mechanical characteristics, cracks primarily initiate near the interface region, and then propagate to the interlayer and the rock salt adjacent to it. The thickness of the interlayer affects the entire performance of the composite specimen and governs the development of the local fractures. Macro-cracks tend to form more easily in the test specimens that contain a medium-thick interlayer than in the ones containing only a thin interlayer. Increasing confining pressure gradually changes the overall mechanical behaviors from brittle to more ductile at higher confining pressure. The ductile behavior is characterized by differences of strain-hardening behaviors and also the geometry of cracks at different locations in the interlayer as compared to the results of uniaxial compression tests.