Abstract:Research purpose: The surrounding rock of Fault F3 of Bieyancao Tunnel on Yichang-Wanzhou Railway Line is broken up. The fault is of gravely soil with local developments of solution crack and fluid bowl, and a little underground water. According to the standard of surrounding rock V Grade, the prevention and support are conducted in advance for the surrounding rock by small pipe, grid steel frame and net spraying concrete, and bench excavation is adopted during construction. Three months later of primary prevention and support, the support for the tunnel is seriously cracked and deformed, and water is burst by large scale because of increments of water volume and water pressure in underground river on right side of railway line (10-20 m far from tunnel), caused by heavy rain. The analysis is made of mechanization for burst water on Fault F3 and an introduction is given to treatment measures for the gushed water in this paper.
Research method: After occurrence of burst water, the following emergency measures are taken on site. Toroidal reinforcement and lateral support are conducted by I-steel, and holes are drilled on right side wall to drain water and decrease water pressure. After stabilization of water volume, the radial reinforcement is conducted for Fault F3 by grouting to block water. The deformed grid steel frames are displaced by steel frame I20 and secondary lining is laid in time.
Research result: After treatment by adopting technical measures of "radial grouting reinforcement-primary support reinforcement-laying secondary lining", only local vadose water occurs on Fault F3 with water volume of one cubic meter per hour. The treatment result is good.
Research conclusion: First, it is known from burst water accident if the watery situation of underground river occurs around tunnel (within 100 meters), once the surrounding rock breaks up, even water is not burst during tunnel excavation, but it is difficult to ensure no occurrence of burst water after ending primary support or no occurrence of problems in service of tunnel. With concept increment of "Strengthen the fundamental and weak the trivial, and service for operation" for tunnel construction, it is necessary to reinforce in advance and make provisions before troubles occur to such geological structure. Secondly, it is an effective way to treat and prevent occurrence of burst water in similar geological structure of Fault F3 of Bieyancao Tunnel.