Study On The Influence Of Weak Interlayer On Tunnel Structure Under Earthquake

Due to the restriction of the route,when the tunnel passes through the rock mass with great lithology difference,the seismic load will make the tunnel structure stress complex,so it is very important to study the seismic dynamic response law of the tunnel passing through the weak interlayer.Based on a railway tunnel in Chongqing,this paper discusses the seismic dynamic response of the tunnel structure under different inclination angle,thickness and elastic modulus of soft interlayer,analyzes the acceleration,displacement,principal stress and internal force data of the top,waist,foot and bottom of the lining,and obtains the dynamic response law of the lining and the lining The safety factor of the structure provides a reference for the aseismic design of the tunnel passing through the weak interlayer.The main research work and conclusions are as follows:(1)Through spectrum analysis and baseline correction of seismic wave,the reasonable seismic wave for numerical simulation is obtained,and a three-dimensional model of tunnel passing through soft interlayer is established.The acceleration,velocity,displacement and stress of lining are analyzed.It is found that soft interlayer can enlarge the seismic dynamic response of tunnel structure,and the displacement and stress of lining at soft interlayer are obviously greater than those at non soft interlayer Weak interlayer.(2)The whole three-dimensional model with different dip angle and thickness of soft interlayer is established,and the change rule of acceleration,displacement and principal stress of tunnel lining with dip angle and thickness of soft interlayer under earthquake is obtained.It is found that with the decrease of dip angle or increase of thickness of soft interlayer,the displacement and stress of lining are increasing;the change of elastic modulus of soft interlayer is studied It is found that the larger the difference between the elastic modulus of soft interlayer and surrounding rock is,the more significant the amplification effect of lining acceleration is,and the greater the displacement and stress of the structure are.(3)According to the strength checking method of reinforced concrete eccentric compression member when it is damaged,the change rule of safety coefficient of each key part of lining is calculated under different inclination angle,thickness and elastic modulus of soft interlayer.It is found that with the decrease of inclination angle or the increase of thickness of soft interlayer,the safety coefficient of lining decreases;the elastic modulus of soft interlayer increases The larger is the lining safety factor.