Case study of risk assessment for safe grade of deep excavations

Based on the risk idea and the safe factors of excavations as well as the weights obtained from the investigations of excavation accidents, the safe grade of excavations is analyzed. First, the development situation, possible risks in the project and the current grade division in excavations are briefly introduced. Then all kinds of reasons obtained from a large number of excavation accidents are statistically analyzed. Each influence factor in excavation safety and its weight are obtained. The fuzzy synthetic evaluation method is introduced, which can be used largely in many projects. At the same time, the judgment matrix is constructed and two levels of judgment for the excavation safety are carried out. Quantitative calculations are made by using the fuzzy synthetic evaluation method. Finally, the excavation project of Shanghai International Passenger Transport Centre is analyzed. The results conform to the actual situations of the project. Thus the fuzzy synthetic evaluation method is favorable for raising the overall safety level of the excavation, and it can provide some reference values for projects.