Research On Seismic Performance Of Shallow-buried Double-hole Ultra-small Clear Distance Tunnel In Soil-rock Combination Stratum

In recent years,with the rapid development of urban tunnel traffic,a large number of tunnel engineering construction in road engineering,but the tunnel structure also faces a series of problems,such as geological conditions,earthquake damage.In this thesis,taking Yuhan road tunnel project in Jinan as an example,the seismic performance of shallow buried double hole ultra small clear distance tunnel in soil rock composite stratum is studied by using numerical simulation analysis method.Based on this,this thesis has done the following work.Combined with the examples of tunnel seismic damage at home and abroad,the types,characteristics and mechanism of tunnel seismic damage are summarized and analyzed;By using finite element analysis software MIDAS / GTS,a two-dimensional simplified model of lining and surrounding rock is established.Through analyzing the tunnel response under different seismic acceleration,different buried depth,different rock column thickness,different lining strength,different rock column material and different inclination angle of surrounding rock,the basic law of shallow buried double hole ultra small clear distance tunnel in soil rock composite stratum is found out.Finally,the deformation and failure characteristics of this kind of tunnel under earthquake are analyzed.The conclusions are as follows:(1)The greater the earthquake intensity is,the more obvious the lining response is.(2)Under the earthquake,the increase of buried depth can better limit the change of tunnel response.(3)The greater the thickness of the rock column,the more limited the displacement of the lining structure,and the more obvious the internal force of the structure.(4)The greater the strength of lining concrete is,the smaller the displacement change is,and the greater the internal force change is.It is not ideal to improve the seismic performance of lining structure only by improving the structural stiffness to resist the seismic deformation of surrounding rock.(5)The strength of rock column material increases,and the seismic effect is obvious.According to this,the stiffness of rock column material can be improved by grouting in practical engineering,so as to achieve the purpose of shock absorption.(6)The larger the dip angle is,the more obvious the seismic response is.