狮子洋水下盾构隧道衬砌结构受力的现场测试与计算分析

以狮子洋水下盾构隧道为背景,对管片衬砌在施工期和后期所受外荷载和结构内力进行长期现场追踪测试,总结衬砌结构外荷载和内力随时间变化规律。并采用三维壳-弹簧计算模型对大断面宽幅管片结构内力分布形态进行研究,与现场测试结果相互验证。研究结果表明:施工期管片衬砌脱环后容易形成无水压环箍作用下土体偏压状态;施工后期水、土压力长期随时间增长,结构内力随之增大,结构轴力较弯矩增幅明显。三维壳-弹簧计算模型适应大断面宽幅管片衬砌结构计算。试验和数值计算结果在量值和分布规律上一致。封顶块处弯矩较小,其弯矩由临近环衬砌结构承担;受环间接头错缝效应影响,幅宽边缘靠近衬砌结构纵缝处轴力发生突变。

Field Test and Numerical Simulation of Mechanics of Segment Lining of Shiziyang Underwater Shield Tunnel

Taking the Shiziyang Underwater Shield Tunnel as the engineering background,long-term field tracing tests were carried out to measure the external load and internal force of the segment lining structure during the construction period of and after-construction stage and to analyze the changing law of the external load and internal force with time.The 3D shell-spring finite model was established to simulate mechanical distribution characteristics of the segment with large section and broad width.The study shows the following results:In the construction period,the lining is easy to enter the bias condition with soil pressure and without water pressure after segments leave the shield trail;in the after-construction stage,with the trend of long-term growth of soil and water pressure,the internal force increases correspondingly and the increment of axial force is more obvious than that of the bending moment;the 3D shell-spring model is applicable to calculation of the lining structure of segment with large section and broad width and its calculated results are in good accordance with the experimental results;the bending moments are relatively small near the topping-out position of segment and the major part of the bending moments are undertaken by adjacent ring segments;influenced by staggered effects of ring joints,the axial forces will change suddenly on the edge of segment near the longitudinal joints of the lining structure.