THE NUMBER ANALYSIS ON PILOT CONSTRUCTION SEQUENCE OF SMALL HEIGHT-SPAN RATIO TUNNEL IN SOFT SOIL

In order to understand the influence of different excavation sequence for tunnel surrounding rock in soft soil, taking the excavation of double-layer tunnel in Chaoyang District as background, the construction is simulated by 3D numerical simulation method. Results are as follows: the better solution is found by considering the change of the surface subsidence, horizontal convergence of the side wall, stress field and plasticized zone distribution; in both two solutions, removal of temporary invert is the most vulnerable step in construction. The result can provide reference and guidance for the follow-up program.