Research On Anti-seismic Technology And Progressive Grouting Scheme For The Soft-hard Rock Section Of The Bias Tunnel Portal In Strong Earthquake Zone

In recent years,with the vertical deepening of China’s traffic construction field,especially in the west,there are more and more tunnels in the mountain tunnel crossing the interface between soft and hard rock.Among them,the tunnel is highly vulnerable to earthquake damage.Therefore,in view of this situation,this paper launches the seismic dynamic response and anti-seismic research of the soft-hard rock section of the bias tunnel.Based on the Feixianguan tunnel entrance engineering,this paper studies the stiffness matching of the progressive grouting area of the tunnel crossing the interface between soft and hard rock by theoretical research and numerical simulation.Further the seismic dynamic response is studied on the soft-hard rock section of the bias tunnel portal.Finally,on the research foundation of the two aspects,the anti-seismic research is carried out.The main research contents are as follows:1、Based on the study of the seismic damage form and mechanism of the tunnel,the anti-seismic technology of existing tunnels is analyzed.2、Based on the theory of elastic mechanics,the progressive grouting analysis model of the tunnel in soft and hard rock transition section is established,and the condition that the radial displacement of the lining is uniformly transitioned in the soft and hard rock transition section is assumed.The analytical formula of the optimal matching stiffness of in progressive grouting area which is in soft rock is derived.3、Based on the Feixianguan tunnel,the numerical simulation of the dynamic response of the biased tunnel under different buried depths through the junction of the hard and soft rock section is carried out.The displacement and stress of the lining structure are studied from the lateral and longitudinal dimensions of the tunnel.The variation and response characteristics of the displacement and stress with the burial depth are obtained,and the position of tunnel damage in different regions is clarified.4、According to the actual situation of the engineering,the anti-seismic effect of the progressive grouting and the damping joint at different grouting ranges and different pitches are studied and the anti-seismic effect of the different ranges of progressive grouting in tunnel surrounding rock and the different intervals of damping joints of tunnel structure is obtained.The application range of progressive grouting and damping joints and methods to enhance their anti-seismic resistance are further summarized.