A New Method of Searching Underground Caverns´ Safety Factor

In order to evaluate the safety margin of large substructure engineering during excavation and design, a new method to calculate the general safety factor of underground multi-cavern is put forward based on the strength reduction theory. The method consists of three techniques: (1) the connection of the equivalent plastic strain is taken as the critical instability criterion of caverns; (2) The way of loop search of safety factor is carried out by reducing strength parameters of material step by step; (3) The numerical constitutive model is elastic-perfectly plastic model with Mohr-Coulomb yield rule. Application in the Laxiwa hydropower station, the largest underground caverns in Yellow River valley, indicates that the method is very useful for analyzing the general stability of caverns and designing of underground engineering quantitatively.