城市地铁双护盾TBM隧道管片受力特征现场试验与计算分析

Field test and calculation analysis on mechanics characteristics of double-shield TBM tunnel segments in urban subway

依托深圳地铁8号线双护盾TBM硬岩隧道工程,对施工全工序隧道管片外围荷载、钢筋和混凝土进行长期跟踪监测,详细介绍了测量元器件布设与安装方法,总结径向压力、钢筋应力和混凝土应力随时间变化规律,并采用三维精细化模型对管片结构内力进行分析研究,并与现场试验结果进行对比验证。研究结果表明:管片径向压力受注浆压力影响主要经历4个发展阶段:下部注浆阶段、上部注浆阶段、缓慢变化阶段及稳定阶段,整体分布不均匀,表现为上下大左右小的“鸭蛋”形。除隧道拱底外侧钢筋处于受拉状态外,其余钢筋均处于受压状态。管片内侧钢筋应力均大于外侧钢筋,内侧钢筋应力最大值为25.68 MPa,钢筋应力比为0.08,位于隧道拱顶;外侧钢筋应力最大值为16.41 MPa,钢筋应力比为0.05,位于隧道左拱腰;管片混凝土应力均为负值,混凝土均处于受压状态,混凝土应力最大值为1.57 MPa,混凝土应力比为0.05,位于隧道拱顶。混凝土应力与钢筋应力变化规律基本一致,验证了钢筋和混凝土协调变形理论的正确性,两者最大值均处于隧道拱顶处。具有环纵向钢筋的三维精细化管片模型可反映隧道管片结构实际受力特征,计算结果与现场测试管片受力变化趋势基本一致。

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.