Tunnel Waterproof And Drainage Technology Research Based On The Limit Drainage Idea

The problem of tunnel water seepage has been now a widespread disease for thebuilt tunnels, which looms large especially in the tunnel design, construction and itsoperation. The water seepage in tunnel will cause the pavement wet and slippy, whichwill threaten the driving securities. The tunnel water seepage can also increase thehumidity in the tunnel, and affects in return to the facilities in the tunnel. In cold areas,the tunnel water seepage will trigger various freeze harms, and deteriorate theconditions of the tunnel. As a result, the treatment of waterproof and drainage of thetunnel have become one of the key issues in tunnel construction areas. Now,construction of tunnels have gradually abandoned the idea, which thinks the mainmeasure of waterproof and drainage is drainage, and begin to implement a newwaterproof and drainage idea, which thinks the main measure of waterproof anddrainage is water plugging, then limit drainage.With Dayaoshan NO.1tunnel as background, the main research contents onthe limit drainage technology are as follows:①Being situated in a certain geological environments, complex geological bodieswere formed over a long geological period of time, the mechanical and seepagecharacteristics of rock mass are different from homogeneous medium. Rock massconsists of continuum rock and discontinuous geological structural planes. Thecomplexity of the structures of rock mass leads to seepage anisotropy. This dissertationis based on the analysis research of seepage theory and its basic equations of variousfractured rock mass. This section expounds the seepage characteristics, the structurecharacteristics and the development of the theory and evolution of seepage of fracturedrock mass;②Based on the fluid-structure coupling theory and its basic equations, this sectionfocus on the effect between groundwater and rock, including the mechanical effect ofgroundwater on rock, and weakening effect of groundwater on rock strength, theinfluence of seepage to the rock mass stress field etc.③By using COMSOL physical field coupling analysis software for numericalsimulation analysis, this dissertation introduces the process of establishing analysismodel of the Dayaoshan NO.1tunnel, and discusses the parameter selection andboundary conditions. Research how the control factors of seepage field affect the seepage field, the stress field of surrounding rock and the displacement distribution。Thecontrol factors contain the underground water level, grouting or non-grouting and thethickNess of grouting. It provides the corresponding theoretical basis for the stress anddeformation control in the actual tunnel limit drainage process.④Numerical simulation results that the underground water level of surroundingrock has a greater influence on the seepage field. Whether grouting or not, the effects tothe seepage field and stress field of surrounding rock are large, such as the tresca stressvalue before grouting is35%larger than grouting. By changing the thickNess andcoefficient of grouting, it can be obvious judged the grouting water plugging effect fromthe change of every field, so you can select the most reasonable grouting plan. Forexample, compare K=1e-5m/d with K=1e-4m/d, z positive displacement decreases0.61%; Negative displacement increases1.34%.The focus of this dissertation will be the engineering example simulation about thegrouting engineering of the reservoir near the surface in Dayaoshan NO.1tunnel byapplying mathematical simulation. It helps the actual project select the suitable plan,and has a positive guidance to the project construction.