Through analyzing the Monte Carlo random finite element and the system reliability method of βembranchment method

we consider to combine the two theories

and then a reliability analysis method is proposed to use in the process of underground caverns excavation. The method for evaluating the big cavern reliability in construction has researched. Taking the Hainan project for example

we analyze the every excavation step

and compare the two methods’ shortcomings and merits. So we can get a full knowledge about the several layers excavating method so as to provide reference for the fast excavating.