Study On Soil Disturbance During Long-distance EPB Shield Tunneling In Water-rich Sandy Strata

The background of the paper comes from the actual project Aigang-New Airport South interzone of Guangzhou subway line 3. By comparing the monitoring results of field tests and finite element numerical simulation, long-distance water-rich sand earth pressure balance shield construction generated Mechanism of soil disturbance, disturbance laws, control methods were studied. Reached the following conclusions:(1) The soil disturbance of the shield construction is the result of multiple factors, in shield construction, strengthen the monitoring and information feedback, adjustment of the construction program timely and increase the skill level of shield operators can effectively reduce the shield construction on soil disturbance.(2) Disturbed soil on the vertical displacement is greater than the horizontal displacement. Ground shield loss due to construction is the direct cause of soil disturbance. Adjust the injection pressure filled construction space timely and avoid the occurrence of snake-like tunneling can be effective in reducing formation damage.(3) Surface subsidence meet the peck theory.Longitudinal affected area is from 18m in front of the incision to 30m behind it, and horizontal affected area is about 3 times of diameter of shield on each side of the tunnel.(4) Finite element simulation results and field test the settlement results can match well, which shows numerical simulation as a tool for the study of shield construction caused soil disturbance works well, while its construction of the shield in prediction the disturbance of soil has a high practical value.