Study On The Mechanism And Treatment Measures Of Tunnel Water Leakage In Liangmao District On The Loess Plateau

Water seepage is a common disease in tunnels and underground engineering.Understanding the seepage mechanism of surrounding rock and groundwater is not only the basis for disease treatment,but also a difficult problem in engineering practice.The biggest feature of Liangmao area on the Loess Plateau is that there is no supply relationship between Liangmao,so its seepage mechanism is different from others.Taking the tunnel passing through an isolated mountain as an example,the paper discusses the relationship between the characteristics of tunnel leakage and surface precipitation,surrounding rock(storage)water and seepage characteristics under specific topography,geomorphology and geological conditions,and analyzes the surrounding rock seepage path and The mechanism was verified by numerical analysis methods,and engineering treatment suggestions were put forward.Taking the Niulangou Tunnel as an example,this paper studies the leakage mechanism of the tunnel in Liangmao District on the Loess Plateau,and then formulates the targeted treatment measures based on the seepage mechanism.The main contents are as follows.(1)First,the basic theory of seepage in fractured rock masses are reviewed,and the properties and seepage of the surface loess layer in the Liangmao area of the Loess Plateau are discussed.Then the geometric characteristics and permeability tensor of the fractures in the rock mass are discussed.The basic equations of body seepage flow clearly define the initial conditions and boundary conditions of the study area.(2)Through on-site investigation of the Niulangou Tunnel on Shenpan Highway,a preliminary analysis of the leakage mechanism of the Niulangou Tunnel from the aspects of topography,geomorphology,hydrology and meteorology,and water leakage detection is carried out.It is believed that the Niulangou Tunnel seepage The path is: the loess layer on the surface of the tunnel site has two large catchment areas.Through the collection and confluence of surface precipitation,under the action of the pressure difference,the well-developed joint fissures in the rock mass are used as channels to seep around the tunnel structure The over-excavated cavity behind the lining provides conditions for the storage of leaking water,and finally penetrates into the tunnel through cracks in the lining or construction joints.(3)Analyze the pore water pressure and seepage velocity of each rock formation in the Niulangou tunnel within 72 hours after rainfall through the finite element analysis software,and obtain the pore water pressure and seepage velocity in the rock formation at a certain point in time within 24-48 hours It reached the maximum value,which coincided with the observation record of the Niulangou Tunnel during the rainfall period-the seepage at the north entrance of the tunnel basically occurred about 40 hours after the beginning of the rainfall.(4)Starting from the seepage mechanism of the Niulangou Tunnel,the treatment measures for the Niulangou Tunnel are given.Firstly,starting from the source of water,a method for block drainage of the surface loess layer catchment area is proposed;then the grouting method is proposed for the rock mass cracks of the main seepage channel;the method of plugging and repairing the lining cracks is proposed;then the well point precipitation is proposed.In order to reduce the water pressure behind the lining,the last is the repair and cleaning of the original drainage facilities in the tunnel.