Study On Mechanical Characteristics And Waterproof And Drainage Technology Of Lining Structure Of Large Section Highway Tunnel In High Pressure And Rich Water Area

With the rapid development of China's economy,the infrastructure construction of mountains' areas has been expanded continuously.The characteristics of the mountains' areas are complex hydrogeology and various landforms.It is decided that a series of geological conditions will be encountered in the process of tunnel construction,such as fractured weak zone,fault,high ground stress,high water pressure and so on.High water pressure is one of the most dangerous problems in tunnel construction and operation,which is related to structural safety during tunnel construction and operation.Under the action of high water pressure,the large cross section highway tunnel with relatively small sagittal span is extremely unfavorable,and the lining structure is easily damaged,but the research results of the domestic phase are less.Therefore,it is urgent to carry out the research on the mechanical characteristics of lining structure of large section highway tunnel in the area of high pressure and rich water.This paper relies on the large section highway's tunnel of Qingyun Mountain.The stress characteristics of the lining structure of the large section highway tunnel in the high pressure water rich's area and the failure form of the lining structure under the action of high water pressure are investigated by the method of data investigation,theoretical analysis,model test and numerical simulation.And the drainage technology has been discussed.The main results are as follows:(1)Based on the theory of similar model,a model test of similar proportion is carried out in the water rich section of IV class surrounding rock in Qingyun Mountain tunnel.The soil pressure loading device and non circular section uniform hydraulic loading device are used to simulate the effect of soil pressure and water pressure respectively.Considered the change of the depth of the tunnel and the height of the head of the water,the large section highway lining in the high pressure water rich area is lined.The stress of the masonry structure is tested.The stress characteristics of the lining structure of two tunnel sections in three lane and emergency parking zones under the joint action of soil pressure and water pressure are investigated.The damage forms of two lining structures under the action of high water pressure are analyzed,and the changes of the inner force of the lining structure of the large section tunnel with the water rich area vary with the water pressure and the depth of the buried.(2)Based on the load structure calculation theory,the ANSYS finite element calculation software is used to establish the initial support and two lining joint bearing structure system model.Considering the joint action of the surrounding rock load and the water load,the force of the two sections of the three lane and emergency stop belt in the high pressure water area deep buried highway tunnel is explored.The influence law of the surrounding rock grade and the change of head height on the stress and safety of the two kinds of cross section lining structure is obtained.(3)Based on the FLAC3 D fluid solid coupling calculation theory and using the FLAC3 D finite difference software,the typical water rich section of the YK349+728~YK349+804 mileage section of Qingyun Mountain tunnel is selected,and the calculation model of "two sides ditch" drainage and the "drainage ditch under the inverted arch" is established respectively,and the fluid solid coupling calculation is carried out.Two kinds of drainage modes are compared and analyzed.The variation of rock seepage flow field,the distribution characteristics of lining outer water pressure and the distribution characteristics of the safety factor of the lining structure are analyzed,and the applicable scope of the two kinds of drainage methods is discussed.