Risk Analysis and Countermeasure Study of Shield Tunnelling in Karst Stratum of China

Abstract

In China, many cities have the experience of shield construction practice in Karst stratum, such as Guangzhou, Nanning, Changsha, Wuxi and Dalian. In the Karst area, there are many construction risks such as groundwater inflow, sand inflow, surface subsidence, cutter head damage and expulsion-retarded of slurry shield. Based on the analysis of the development mechanism of the Karst and the practice of the shield tunneling in the Karst stratum of Guangzhou and Nanning Metro, this paper analyses the main risks in the process of shield tunneling, and according to concrete construction risks, it proposes concrete controlling measures from the aspects of planning of the line shallow buried, the pretreatment of the Karst cave and shield selection and construction control, which provides significant guidelines for the shield tunneling under the similar Karst stratum condition.