Simulation analysis of excavation and support of large cross-section soft surrounding rock tunnel based on FLAC3D

Weak surrounding rock usually refers to the surrounding rock structure with low hardness and cementation degree, and is extremely susceptible to weathering conditions. In the actual construction process, the main reason is that the stress level is low, or the buried depth condition is poor, etc., which causes obvious construction deformation problems in the surrounding rock construction area and reduces the main construction safety. With the excavation of large-section tunnel in weak surrounding rock as the background, the finite difference software FLAC3D was used to simulate the advance grouting support of large-section tunnel in weak surrounding rock. This paper calculates and analyzes the step-by-step excavation of the tunnel, studies the displacement change and stable state during the tunnel excavation, and puts forward corresponding preventive measures and suggestions. The analysis results provide theoretical support for the tunnel construction control.