Abstract:

Slender West Lake Tunnel in Yangzhou of China is located in full clay strata. However, so far there are few cases of slurry shield boring in full clay strata. Therefore, the mechanical properties and deformation law of full clay strata during shield boring need further study. In order to obtain the relationship between the excavation face stability and the various parameters during shield boring in clay strata, the author studies the stability of the excavation face of Slender West Lake Tunnel by means of laboratory tests and simulations. The results showed that: 1) When the shield boring is suspended, the slurry infiltrates into the soil mass in front of the excavation face constantly, the soil stress near the excavation face has certain arching effect, which leads to the continuous reduction of the stability of the excavation face; 2) Under the same slurry infiltration time, the ultimate support pressure for the excavation face has an increase tendency as the expansion force of the expansive soil increases; 3) Measures to stabilize the excavation face are proposed according to the causes for the excavation face failure and are also verified by model calculations. 

Key words: Slender West Lake Tunnel in Yangzhou, slurry shield, clay strata, excavation face stability, supporting pressure ratio