Research On Dynamic Depth And Shallow Partition Subdivision Of Tunnel Based On Pressure Arch Theory

With the increasing number of tunnels which were built in high-intensity areas,earthquakes have become a factor that must be considered in the construction of tunnels,and the designing of tunnels has a great relationship with the depth of the tunnels.Therefore,how to determine the state of shallow buried tunnel under the action of earthquake has become an urgent problem to be solved.There are many factors affecting the determination of the depth of the tunnels,including: tunnel span,surrounding rock grade and its physical and mechanical parameters,source location,tunnel depth,seismic intensity,etc,which is making it difficult to accurately determine the boundaries of tunnel dynamics.At present,the method of judging the depth and the depth of tunnel dynamics still adopts the static method,considering the less seismic dynamic conditions.Therefore,the study of tunnel dynamic deep and shallow buried division under seismic conditions has positive theoretical guiding significance and social value.Based on the theory of pressure arch and the relying on engineering,this paper conducts a preliminary study on the division of dynamics depth and shallow depth of tunnel under seismic conditions.And the relationship between the buried depth of the tunnel and its influencing factors under the dynamic conditions is analyzed using the combination of theoretical analysis and numerical analysis.The main research results are as follows:(1)Using the Bill Bowman formula in the pressure arch theory,the calculation formula of the boundary depth of the tunnel under the seismic conditions is derived,and the main factors affecting the calculation results of the formula are analyzed.(2)Based on the pressure arch theory,the Midas GTS NX finite element software is used to establish the calculation models under different influencing factors,and the factors affecting the depth of the buried depth of the tunnel,namely the seismic intensity,the surrounding rock level and its physical and mechanical parameters,the tunnel span,the tunnel depth and the tunnel section shape,are analyzed as the influencing factors,and the relationship between the height of the tunnel pressure arch and the depth of the tunnel under different factors is obtained.(3)By analyzing the linear relationship between the height of the tunnel pressure arch and the depth of the tunnel,the depth and depth of the tunnel under different influencing factors are obtained,furthermore,the relationship between the depth anddepth of the buried depth of the tunnel and the specific influencing factors is obtained,and the formula for determining the depth of the buried depth of the tunnel under the influence of different factors and the applicable conditions of each formula are determined.(4)Taking the project as an example,the calculation results obtained by the pressure arch theory analytical method and the numerical analysis method are compared with the calculation results of the empirical formulas in the relevant specifications to verify the rationality and practicability of the research results.