Study On Coupling Mechanism Of Seepage With Stress And Limited Discharge Of Groundwater In Fractured Rock Mass Tunnel

With the increasing development of transportation in China,railway tunnel,highway tunnel and urban rail transit are an important link of link transportation hub.As tunnels are often in the underground,or in cities,or in mountain areas,it is more or less unavoidable to suffer from the seepage of groundwater or the impact of inrush of water.In the construction and operation stage,in order to ensure the sustainable development of the construction staff's safety,engineering quality and natural ecological environment,it's a very important topic to study the seepage rule of groundwater and prevent it.On the basis of summing up and summarizing the achievements of previous studies at home and abroad,this paper adopts the method of theoretical analysis,numerical simulation and the combination of engineering practice.The effects of hydraulic characteristics,seepage characteristics,seepage field and stress field coupling mechanism,and structural plane characteristics on the seepage flow field and seepage discharge theory of jointed rock mass have been studied in depth.(1)The seepage characteristics,fluid solid coupling mechanism,formation mechanism and influence of seepage phenomena of fractured jointed rock mass are summarized,and the problems at the present stage are put forward.(2)The hydraulic characteristics of fractured rock mass are systematically summarized,including the structural plane characteristics of fractured rock mass,the seepage characteristics of fractured rock mass,and the coupling theory analysis of seepage and stress under single crack condition.(3)The common fluid solid coupling models are introduced,and the basic principle and calculation model of the seepage theory of fractured rock mass based on the Discrete Element Method are expounded in detail,and the coupling mechanism of the seepage field and the stress field is further expounded.With a case study of fluid solid coupling,the effects of coupling and uncoupling on the stress field,displacement field and seepage field are analyzed.The difference of groundwater seepage field be-tween random joints and conventional joints is analyzed.There are obvious differences in displacement,stress and seepage.(4)The numerical simulation analysis is carried out by the Discrete Element Method.These effects of joint dip angle,joint spacing,initial pore water pressure,joint normal stiffness,joint tangential stiffness and initial ground stress on the seepage field are discussed respectively.The sensitivity of the seepage field to various factors is revealed,in which the dip angle,spacing,initial pore water pressure and initial ground stress have great influence on the seepage field of the joint tunnel,but the normal stiffness and tangential stiffness have a little influence.(5)First,the significance of limited emission in tunnel engineering is expounded.Then the theory of groundwater seepage discharge is introduced.Theoretical calculation,analytical solution and numerical solution are carried out through an engineering example.Finally,the two cases are compared and analyzed,and some suggestions for engineering practice are put forward.