Distribution characteristics and evolution laws of liner cracks in underground caverns for compressed air energy storage

The liner of underground gas storage cavern is used to transfer the internal pressure to the surrounding rock, and at the same time serves as the base of flexible sealing layer. The excessively wide cracks due to the high internal pressure may lead to generation of reflective cracks in the sealing layer, thus causing the leakage of high-pressure gas. To deeply understand the characteristics of liner cracking in high-pressure underground gas storage cavern, a routine for cracking analysis of a liner based on the FLAC^3D platform is developed, and the influences of reinforcement mode and ratio, concrete cover thickness, surrounding rock type and effect of temperature-pressure cyclic loading on cracking evolution characteristics are studied. The research results show that the crack width of the liner can be effectively controlled by reasonable reinforcement of concrete liner and improvement of the surrounding rock quality. For a circular cross-section tunnel gas storage cavern, it is possible to control the maximum crack opening in the liner by differentiated reinforcement mode, so as to reasonably reduce the reinforcement quantity in the liner. The thermo-mechanical coupling effects due to the simultaneous change of compressed air pressure and temperature are helpful to reduce the crack width in the liner.