Model Test On Advance Deformation Law And Control Measures Of Shallow-buried Tunnel In Weak Surrounding Rock

This paper analyzes the three-dimensional deformation and stress variation of surrounding rock in front of the tunnel face in soft surrounding rock.The control effect of typical advanced deformation control measures is also analyzed.Research methods such as model tests,theoretical analysis and numerical simulation has been used The main research contents and conclusions are as follows:(1)The deformation mechanism and influencing factors of tunnel surrounding rock are analyzed,and the deformation of surrounding rock caused by tunnel construction is calculated.Nine sets of model test protocols were designed.The test geometry similarity ratio was 1:55.The similar materials of the V-class surrounding rock and the lining similar materials were obtained under the corresponding similar ratios.The indoor similarity model test of shallow buried tunnel construction was carried out.(2)The three-dimensional advanced deformation law and stress response of the surrounding rock in front of the face of the tunnel caused by tunnel construction are analyzed.The significant factors affecting the maximum advance deformation and its range are summarized.Divide the front layer of the face into three areas.The I area(0 to 0.5D)is a dangerous area with the leading deformation as the main controlling factor.The deformation of the surrounding rock in this area increases sharply,and the earth pressure is released rapidly.The II region(0.5 to D)is a transition region.The deformation of surrounding rock in this area gradually increased,and the vertical pressure gradually released,showing an accelerating trend.The ? area(1 to 1.5D)is the area affected by the disturbance of the formation.The deformation of surrounding rock and soil pressure are relatively small but both show an increasing trend.(3)A numerical calculation model is established based on a certain section of the Metro Line 4 project.Working conditions include different methods of dug tunnels(two-step core soil method and full-section method),and whether there are reinforcement measures.The pre-deformation law is verified by comparing the calculated data with the engineering monitoring data.The control effect of the control measures on the advanced deformation is also analyzed.