Research on the relationship between the tunnel stability and the depth of drainage ditch

Further excavation of tunnel´s drainage ditch could help to lower the groundwater level and ensure the tunnel´s safe operation. However, the excessive excavation of drainage ditch would impact on the tunnel stability. Using field tests to study the excavation depth entails high risk and the result is irreversible, so this method is unfit. The elastic-plastic finite element method was used in the paper to simulate the excavation process of drainage ditch and discussed the relationship between stability of tunnel and the depth of ditch. The optimum depth of Lijiatuan Tunnel´s drainage ditch is 0.77 meter. In the process of ditch´s further excavation, this value was taken as the upper limit for construction, and the treatment effects were satisfied.