Seepage Characteristics And Water Inflow Prediction Of New Tunnels Under Existing Tunnel Conditions In Karst Trough Area

In the process of construction of roads and railways,the choice of different road linings will affect the tunneling through the mountain,and the tunnel through the mountain,the tunnel elevation is generally below the groundwater level,the tunnel excavation will inevitably consider the groundwater influences.Municipal roads,high-speed rail and subway tunnel construction,in order to solve the needs of urban traffic congestion,the need for expansion of certain traffic arteries,the same area of the construction of the tunnel density is higher and higher,then the new tunnel will inevitably be close to some Completed and operated tunnels.At this point the construction of new tunnels will destroy the seepage balance of existing operating tunnels.If a large number of new tunnel gushing water gushing,will inevitably affect the operation of the tunnel gushing water and pore water pressure,and thus cause the surrounding rock surrounding rock stress changes affect the tunnel safety.The drainage of the same tunnel will also affect the gushing of the new tunnel.If there is no restricted drainage in the new tunnel excavation,the groundwater and surface water resources will be lost and may even cause the surface vegetation and human life to be depleted.In this paper,the tunnel construction in Nanshan area of Chongqing city is taken as the research background.Based on the field test,theoretical analysis and numerical simulation,the proposed tunnel construction between Nanshan tunnel and Tongluoshan tunnel is studied.The drainage of Nanshan tunnel and Tongluoshan tunnel and the seepage characteristics of groundwater and the prediction of water inflow in tunnels under existing tunnel conditions.Based on the investigation of hydrogeological conditions in Nanshan area,the seepage field of groundwater after the tunnel excavation is forecasted and the displacement of existing tunnels is forecasted and the amount of water in the construction of the proposed tunnel is predicted.The main research contents include: First,the study of hydrogeological conditions in the tunnel area.Organize the field investigation and indoor test data,including the geological conditions of the region,water chemistry analysis data,rock permeability coefficient data.According to the groundwater recharge,runoff and excretion in the tunnel area,the general model boundary is determined and the main parameters of the model are determined.Followed by the karst trough area operating tunnel drainage forecast study.The analysis of the main tunnel drainage monitoring data in Nanshan area of Chongqing has been carried out.The information of weather and rainfall in Nanshan area is collected and the relationship between water inflow and rainfall is studied.Analysis of the new tunnel excavation,operating tunnel drainage changes.And then the study of groundwater seepage characteristics and water inflow in new tunnels in karst trough area.Based on the characteristics of the surrounding rock of the tunnel and the permeability coefficient of the surrounding rock,the numerical model of the three-dimensional numerical analysis is established by using Midas GTS NX to calculate the variation law of the tunnel water inflow under the permeability coefficient of different surrounding rock,and provide the theoretical support for the planned forecast of the tunnel water.