连接螺栓对类矩形盾构隧道结构极限承载力影响的试验研究与分析

针对类矩形盾构隧道衬砌结构纵向接缝处弯矩正负性确定的特点，对纵向接缝连接螺栓位置进行了优化。基于结构整环足尺试验结果，对比分析了优化前后衬砌结构整体变形、接缝变形和螺栓应变的发展，研究了优化前后结构设计阶段受力性能、破坏机制、极限承载力和鲁棒性的异同。研究结果表明：①螺栓位置优化对结构设计阶段受力性能影响较小；②优化后结构在带缝工作阶段的受力性能明显提升，结构整体刚度提高，极限承载力提高30%；③优化后结构破坏呈延性破坏特征，属于塑性铰机制，结构结构整体安全性得到提高。

Experimental investigation and analysis on effect of connecting bolts on ultimate bearing capacity of quasi-rectangular shield tunnel

Based on the notable characteristic of the quasi-rectangular shield tunnel lining that the direction of the moment at the longitudinal joint is definite, the positions of the longitudinal joint bolts are optimized. Full-scale ring tests were conducted on one normal tunnel ring and one designed with the optimization method. The deformation of the lining, the deformation of the joints and the development of bolt strains were compared and analyzed. Furthermore, the mechanical performance, the failure mechanism, the ultimate bearing capacity and the robustness index were studied. The research results show that the optimization of bolt positions at longitudinal joints had little effect on the mechanical performance in the structural design stage. For the tunnel lining with the optimum design, the mechanical performance in cracking stage are improved significantly. The overall stiffness of the structure is raised and the ultimate bearing capacity is increased by 30%. The failure mode is ductile failure with plastic hinge mode, so the overall safety of the optimized structure is improved.