Abstract:For the three main problems remaining to be solved in the construction process of deep excavation engineering: building a risk index system, distributing the weight of evaluation indexes and evaluating the risk, this article builds a risk evaluation system based on the DS(DempsterShafer) evidence theory combined with interval number theory. Firstly we identify the risk factors by “WBSRBS” and “01” methods to build the risk index system based on the construction principle and management process of deep excavation. In order to decrease the subjectivity of the process of deep excavation risk quantification, then we combine the advantages of interval number theory and DS evidence theory to specify the methods and procedures about how to build identifying framework, choose the reliability function and synthesize information. At last, the rationality and feasibility of the risk evaluation system are manifested by analyzing the example.