Study On Waterproof And Drainage Technology Of Mountain Tunnel In High Pressure And Rich Water Area Based On Blocking Groundwater And Limiting Discharge

With the development and improvement of China's road network,the construction of deep buried long mountain tunnels will inevitably pass through the area with rich water and high water pressure.Under the condition of high demand for the ecological balance of the water environment,the problem of groundwater,especially the rich water with high water pressure is the key problem in the process of construction.Based on the South beam high-speed Huayingshan tunnel engineering and the principles of waterproof and drainage of"mainly by blocking,limited emission",the distribution law of water pressure on lining and the influence of water pressure on lining internal force response are studied by means of theoretical analysis and numerical simulation in this paper.The main research results are as follows:1?The principles of waterproof and drainage of mountain tunnel in the rich water area with high water pressure are described.Based on the theory of axial symmetry,the formula of the external water pressure of the lining under the condition with and without grouting,the formula of the water inflow in tunnel,and the groundwater flow equation in equivalent continuum are derived.In this paper,the selection of the flow solver in FLAC3D is analyzed,and the feasibility of calculating of the fluid-solid coupling problem by the finite difference method is demonstrated.2?As the location of the connection between the external drainage system and the drainage system in the tunnel,the discharge hole has a great influence on the transverse distribution of water pressure.In this paper,two kinds of drainage schemes are put forward,which are located at the arch foot and invert,and the influence of the external water pressure distribution and the structural safety is studied by numerical simulation method.3?Numerical simulation is used to study the influence of the vertical spacing of the discharge hole on the distribution of water pressure and the stress characteristics of the structure.The periodic distribution law of the lateral water pressure along the axial direction of tunnel lining structure is studied,and the cycle of law is the vertical spacing of the discharge hole.The more the space between the discharge holes increase,the higher the stress of the lining structure and the external water pressure outside the arch is.4?Based on the system of water shutoff and limit,the principle of confined discharge in the external drainage system of lining is put forward.By using the numerical simulation method and controlling the different pressure relief value,the effect of pressure relief on the distribution of water pressure and the internal force response of lining structure are studied.The results show that when the limit pressure of the draining hole is increased by 0.2MPa in turn,the external water pressure of the lining of the vault and the skewback near the section of the draining hole is increased by about 5m and 12m respectively,the internal force of the lining structure increases,and the effect of horizontal stress on lining structure is greater than that of vertical stress.