DYNAMIC RISK ASSESSMENT METHOD AND APPLICATION OF LARGE DEFORMATION OF HIGH GROUND STRESS TUNNEL DURING CONSTRUCTION PERIOD

A simple and practical tunnel large deformation risk assessment method is of great value for disaster prevention and engineering applications. We applied the index scoring method to establish a dynamic risk assessment method for large deformation of high ground stress tunnels during construction. Then we established a risk assessment index system of large deformation, which includes three primary indicators consisted of geological factors, design factors and construction factors, and 18 secondary indicators such as rock strength and surrounding rock integrity. Statistical analysis was used to determine the weight of each index. Through the on-site scoring of each indicator, the risk probability level was determined according to the large deformation risk probability level standard. Then we used expert surveys to estimate direct economic losses, delays in construction, and determine severity level. Considering the possibility of risk occurrence and the severity of the loss, we used the risk matrix method to obtain the risk comprehensive level. Furthermore, we applied the established risk assessment method to the Miyaluo Tunnel No. 3 in the Wenma Expressway under construction. The evaluation results were consistent with the actual excavation results, which verified the effectiveness and practicability of the method. This risk assessment method provides a scientific basis for the prevention and control of large deformation during tunnel construction.