Model Test And Evaluation Of Vertical Bearing Characteristics Of Tunnel Lining Under Different Conditions In Landslide Area

In the process of tunnel construction,many times the tunnel will have to be near or even directly across the landslide area.The relative position of the sliding surface and the tunnel is different,which will affect the tunnel to different extent.It is very important to study the stress,deformation and bearing capacity of tunnel lining under different sliding surface conditions for the selection of tunnel location and the design of tunnel lining.Based on the vertical loading model box developed by the research group and considering the influence of four different sliding surface conditions: no sliding surface(condition one),the sliding surface above the tunnel(condition two),the sliding surface passing through the tunnel vault(condition three)and the sliding surface passing through the whole tunnel(condition four)under the tunnel landslide orthogonal system.Model test of vertical bearing behavior of tunnel lining in binary stratum slope under different conditions in landslide area is carried out by means of vertical loading on the top of slope.The vertical bearing behavior,deformation characteristics of tunnel lining,the change of soil pressure in slope and the failure mode of slope are studied and combined with ABAQUS finite element software to analyze the deformation of tunnel lining at same time.The main conclusions are as follows:(1)Under the same load condition,the area where the bending moment of tunnel lining under other working conditions exceeds the maximum bending moment of lining under working condition one is defined as "vulnerable area".In condition two,the vulnerable area of the tunnel lining is the smallest,accounting for 3.6% of the tunnel lining section area.The vulnerable area is located at the arch shoulder of the tunnel lining on the side near the slope surface.In condition three,the vulnerable area of the tunnel lining is large,accounting for19.2% of the tunnel lining section area.The vulnerable area is distributed in the arch crown of the tunnel lining and arch shoulder of the tunnel lining on the side near the slope surface;In condition four,the vulnerable area of tunnel lining is the largest,accounting for 52.8% of the tunnel lining section area.The vulnerable area is distributed in the arch crown,arch foot and both sides of the arch waist of the tunnel lining.(2)The maximum bending moment of the tunnel lining under condition four is located at the side of the lining away from the slope camber,at the arch shoulder of the tunnel lining on the side away from slope surface.The maximum bending moment of tunnel lining under other three working conditions is located at the arch shoulder on the side near the slope surface.Compared with condition one,the maximum bending moment of tunnel lining in condition two increased by 4.2%;the maximum bending moment of tunnel lining in condition three increased by 35.5%;the maximum bending moment of tunnel lining in condition four increased by 81.5%.Under the condition of vertical loading on the top of the slope,the risk of tunnel lining damage increases with the decrease of the distance between the sliding surface and the center of gravity of the tunnel.(3)Due to the difference of stiffness between the upper loess and the lower remolded loose mudstone of the double-layer slope,the stiffness of the Loess part is smaller,and that of the mudstone part is larger.The deformation of the tunnel lining under the four working conditions is concentrated in the upper part of the tunnel lining in the Loess part of the slope.Among them,the vertical deformation of the lining vault is large,and the horizontal deformation of the abutment near the slope side is large.Under the four working conditions,the deformation degree of the sliding surface passing through the whole tunnel is the largest,the sliding surface passing through the tunnel vault is the second,and the deformation of the tunnel lining without the sliding surface is the smallest.