Numerical simulation on cavern support of compressed air energy storage(CAES)considering thermo-mechanical coupling effect

A reasonable support could ensure the stability and tightness of underground caverns for compressed air energy storage (CAES). In this study, ultra-high performance concrete (UHPC) and high-temperature resistant polyethylene were used for structural support and tightness of caverns excavated in hard rock. Laboratory experiments were conducted to investigate the fatigue tensile and compressive behavior of UHPC, and a fatigue damage constitutive model for UHPC was established. A two-dimensional precise thermal-mechanical coupled dynamic model of long-term CAES was developed by the finite element method. Stress and damage evolution of the UHPC lining for both short and long term have been stated, and the extent of crack propagation was evaluated. The numerical result proves that the qualities of rock have significant effect on stabilities of CAES. Finally, transient heat transfer equations and energy balance were used to analyze the heat transfer for CAES, which showed that the thermal stress caused by temperature variation would cause an increment of tensile stress in UHPC lining, and the energy loss rate would decrease to a certain level during CAES cycles. This creative cavern support provides a new method for the design of CAES in the future.