Modeling of the rock mass deformations effect on deep metro main line tunnels

The article discusses the effects of soil mass movement on deep metro main line tunnels. The study is based on the data obtained as part of a field survey of a tunnel section that was exposed to a non-routine event. Displacements of the soil mass surrounding the tunnel during its operation may occur due to disturbance of the groundwater mode caused by abundant water inflow into the tunnel. Solution cavities, especially those filled with water, can also cause deformation of the tunnels during operation, resulting in water inflow into the tunnel. If these cavities are filled with loose sediments, this can also cause significant local loads on the tunnel lining. A number of numerical experiments were carried out to assess the possibility of horizontal displacements of the tunnels, which involved modelling of a 25 m long section of the soil mass enclosing the tunnel. The first stage involved modelling of the soil shrinkage due to progressive shield tunnelling, while the second stage simulated the horizontal displacement front. Dependences of the lining displacement on the distance to the displacement front of the soil mass have been established. Numerical experiments showed that the main geological processes that could lead to deformation of the tunnels occurred at a distance of more than 20 m from the edge of one of the tunnels.