Compressed air energy storage (CAES) is a promising energy conversion storage technology and underground salt caverns are recognized as the appropriate storage places for it. The reduction of air during the withdrawal periods leads to the surrounding rock being unloaded, which threatens the stability of the salt cavern. To investigate the mechanical behavior of surrounding rock under different unloading rates, the confining pressure unloading tests in six unloading rates have been conducted on rock salt. Results show the rock salt undergoes volume expansion at the beginning of unloading due to the reduction of elastic compression strain. The volume strain expands rapidly beyond a threshold, i.e. accelerated strain point. The stresses at failure point and accelerated strain point show that a low unloading rate is beneficial to enhance rock strength. Nevertheless, larger inelastic strain appears in a lower unloading rate. The effect of the unloading rate on rock salt failure mode is that rapid unloading will promote crack growth. Moreover, the relationship between the unloading rate of surrounding rock and the air withdrawal rate is established. The outcome derived from the research can provide some instruction and inspiration for air withdrawal rate design in CAES.

压缩空气能量存储（CAES）是一种很有前途的能量转换存储技术，地下盐穴被认为是适合其存储的地方。撤出期间空气的减少导致周围岩石被卸载，这威胁了盐穴的稳定性。为了研究围岩在不同卸荷速率下的力学行为，对岩盐进行了六种卸荷速率的围压卸荷试验。结果表明，由于弹性压缩应变的减小，岩盐在卸载开始时经历了体积膨胀。体积应变迅速膨胀超过阈值，即加速应变点。破坏点和加速应变点处的应力表明，较低的卸载速率有利于增强岩石强度。然而，较大的无弹性应变以较低的卸载速率出现。卸荷速率对岩盐破坏模式的影响是快速卸荷将促进裂纹扩展。此外，建立了围岩的卸荷率与排风率之间的关系。研究的结果可以为CAES中的抽气速率设计提供一些指导和启发。