Abstract: The determination of initial geo-stress of rock mass is the basis of stability assessment for underground cavern. By analyzing the in-situ measurements of geo-stress, we investigated the effect of geological structure such as fault on the initial geostress distribution, and found that the deformation modulus ratio of the surrounding rock mass is one of the most important factors affecting the initial geo-stress. We also presented a back analysis method in consideration of  the variable stiffness which reflects the stress release induced by faults. The calculation results of initial geostress involving and not involving the effect of fault effect are compared with the measured values, and it's found that the result considering the fault effect is more consistent with the measured result, which verifies the rationality of this method. 

Key words: underground cavern, initial geo-stress field, variable stiffness, tectonic stress release effect of fault