Principle Of Roof Supporting Tube And Interruption Of Excavating Deduced By Water Penetration In Thin Soft Rock Layer Under Water

In 21st century, underground engineer will be very common, and the tunnel across sea or river will be first selection schedule. Many technical problems caused by excave under shallow layer will become the hot point which focused by researchers. Combined with the projects "study on key problem and its application of construction in thin soft rock layer under water"(sponsored by Changsha Bureau of science),"study on key problem of construction in thin soft rock layer under water"(sponsored by China Tunnel limited Group) and Chinese Natural found(No.50878213),with the background Liuyanghe under river tunnel engineering, the principle of roof supporting tube and the influence on rockmass stability deduced by water penetration is analyzed in this disseration. In the period of research, consideration of different site, i.e tunnels in small distance or separated state, the research work are singlely done. The main content includes followings:1) Summary of reinforcement principle of roof pre-supporting tube is made. Combined with the underwater tunnel, and on the base of detail analysis,the selection of supporting structure and parameters of roof pre-supporting tube is realized.2) Depended on continuous beam theory, the interaction model of roof pre-supporting tube and surrounding rockmass is founded. With interruption format,turning angel and tension moment and anti-force fonnat of roof pre-supporting tube, the analysis model of excave face stability is established.3)Construction method about tunnels construction in small distance and realibity of roof pre-supporting tube are studied, i.e.:(1)The space effect of rockmass deduced by excave in different construction methods and different construction schedule.(2) the height and scope of space effect of rockmass after reinforcemented by roof supporting tube is determined.(3) After the disadvantage of loads combination and weak site in tunnel during excave being obtained, the theoretical clue and decision policy of construction schedule will be got.4) Construction method about tunnels construction in separated state and realibity of roof pre-supporting tube are studied, i.e.(1) Expounded the basic equation for saturated seepage in porous media basing on the seepage continuity equation and the seepage movement equation, and gave forth a group of partial differential equations for seepage in fluid-solid coupling cases and the deterministic condition of solution inferred from the Biot Consolidation Theory.(2) Simulated the construction of Liuyang River Underwater Tunnel basing on FLAC-3D numerical methods, improved upon the traditional numerical methods in representing fluid-solid coupling effects, taking accounts of both the fluid-solid coupling effects and the combined action of wall rocks and shoring structures, established fluid-solid coupling models to represent soil-rock mechanical characteristics and water flow, and analyzed the mechanical effects of the underwater tunnel during each construction stage.(3) With the second development of F1AC-3D, the representation of each equation for fluid-solid coupling interaction in the three-dimensional differential procedure FLAC-3D, and the general modeling methods in FLAC-3D for solution is realized. And then the, the stability of excave face and surface settlement caused by excave in different water levels, are all acquired.