Abstract:

Liangshan tunnel is one of the key works on XiamenShenzhen railway. During the construction of the tunnel, water gushing and mud inflow often occur, due to the deepcovered waterrich steep soft fracture zone met. In the paper, the characteristics of the water gushing, mud inflow and ground surface collapse are studied, and the water gushing and mud inflow mechanism is analyzed. It is concluded that fullyweathered materials and ground water under the effect of high seepage pressure difference induced by tunnel excavation are the main causes for the water gushing and mud inflow, and that the ground surface collapse is induced by the sudden drop of the ground water level. After investigation, theoretical analysis and tests, it is determined that longdistance horizontal jet grouting piles be used to reinforce the fracture zone. The layout, construction process and inspection standard of the jet grouting piles are also presented in the paper. The practice shows that the longdistance horizontal jet grouting piles mentioned are feasible and effective in the consolidation of the fracture zone.

Key words: Liangshan tunnel, rich water, steep and soft strata, water gushing and mud inflow, ground surface collapse, horizontal jet grouting