ABSTRACT
Rock mass unloading and relaxation is one of the most prominent problems during the engineering construction in high terrestrial stress region. The relaxation of rock mass can be regarded as a phenomenon of surface instability, with the main performance of rock burst, onion skin, appear tensional fissures which extend for a large scope and generally parallel with the excavated section, and also the deterioration of rock mechanical parameters is the salient feature of the relaxation process. Generally speaking, in addition to the rapid and small-scale disintegration of rock burst, the relaxation process is usually changing as time goes on, and the rock mass after damage still has some residual strength.
