Study On Stability Of Slope And Surrounding Rock In Shallow Unbalanced Section Tunnel

In recent years,the construction of urban infrastructure in China has been accompanied by the rapid development of economy,especially the rapid development of urban road and track engineering.However,due to the limited urban space and different geological conditions,various underground projects have been planned,of which the double-track medium and short tunnels are the best choice.Taking a tunnel project in Sichuan Province as an example,combined with advanced geological prediction,numerical simulation analysis and on-site monitoring,this paper systematically studies and analyses the surrounding rock deformation and the stability of surface slope in shallow buried section of double-track tunnel.The main results obtained are as follows:(1)The surrounding rock deformation of tunnel under special geological conditions is introduced,and the construction technical characteristics of tunnel under biased pressure are emphatically studied.(2)The load distribution of single and double tunnel eccentric pressures is calculated theoretically,and the surrounding rock deformation mechanism of shallow-buried eccentric pressure tunnel in construction is summarized.The safety factor of slope sliding surface is analyzed in detail by the finite element Mohr-Coulomb strength method and reduction coefficient method,which provides a strong theoretical support for the stability of surface slope.(3)Taking a tunnel project in Sichuan Province as an example,a three-dimensional model is established by MIDAS-GTS and numerical analysis is carried out.Stress and deformation of shallow buried section of tunnel under special geological conditions are analyzed.Stress distribution characteristics of shallow and deep buried side of tunnel are discussed.(4)Based on the field measured data and combined with the numerical simulation results,the section excavation of shallow buried section of tunnel is analyzed concretely.The section deformation distribution law of different excavation stages under eccentric pressure is discussed,and the differences between numerical simulation and field measurement are summarized,and the corrective suggestions are put forward.(5)The influence of excavation in shallow section of tunnel on the surface slope of shallow section is studied,and the stability of the surface slope of shallow section is analyzed,thus reasonable and effective slope protection measures are put forward.