Abstract:
Based on the double-shield TBM hard rock tunnel project of Shenzhen Metro Line 8, the long-term follow-up monitoring of the external load, reinforcement and concrete of the segment in the whole construction process is carried out.The layout and installation methods of the measuring components are introduced in detail, and the law of the radial pressure, reinforcement stress and concrete stress varying with time is summarized.The internal force of the segment structure is analyzed and studied by using the three-dimensional refined model, which is verified by the field test results.The research results show that the radial pressure of segment in the influence of grouting pressure mainly goes through four stages:bottom grouting stage, upper grouting stage, slow change stage and stable stage, and the overall distribution is uneven, showing a “duck egg” shape with big upper and lower sides, small left and right.Except for the steel bar in the outer state of the arch bottom, the other steel bars are under pressure.The inner steel bar stress is larger than the outer steel bar stress.The maximum stress of the inner steel bar is 25.68 MPa, and the stress ratio of the steel bar is 0.08, which is located at the vault of the tunnel.The maximum stress of the outer steel bar is 16.41 MPa, and the stress ratio of the steel bar is 0.05, which is located at the left arch waist of the tunnel.The stress of segment concrete is negative, the segment is in compressive state, the maximum stress of concrete is 1.57 MPa, and the stress ratio of concrete is 0.05, which is located at the vault of tunnel.The variation law of concrete stress and steel stress is basically the same, which verifies the correctness of the theory of coordinated deformation of steel and concrete.The maximum values of both are at the vault of tunnel.Three-dimensional refined segment model with circumferential and longitudinal steel bars can reflect the actual stress characteristics of tunnel segment structure, and the calculation results are basically consistent with the trend of the field test segment stress.