盾构法T接隧道结构受力现场试验研究——以宁波轨道交通3号线联络通道为例

为了了解盾构法T接隧道在施工过程中主隧道外部的荷载以及响应，以国内第一条使用机械法施工的联络通道--宁波轨道交通3号线为背景进行研究。本文通过研究施工过程中的施工工况节点，现场监测主隧道结构的外荷载、收敛变形并计算结构内力，得到在整个施工过程中主隧道的结构响应及其变化规律。通过本文的研究，可以得出以下结论： 1）施工过程可依据外部荷载和结构体系进行划分工况，各工况具有明显的不同响应； 2）始发端和接收端的内力变化主要受到盾构顶力和外部注浆荷载的影响，且主要影响切削侧，切削过程中的内力增量在10%～20%，注浆压力影响的增量部分达到了50%； 3）各环及内支撑轴力增量在200 kN以下，破洞位置导致的轴力损失可以由其余位置共同承担，不需要特殊的破洞阶段超载设计。

Field Test on Structural Mechanism of T connected Shield Tunnel：a Case Study of Connecting Passage on Ningbo Metro Line No. 3

The external load and response of main tunnel of a T connected shield tunnel on Ningbo Metro Line No. 3 are analyzed. And then the construction conditions during construction are studied, the external load and convergence deformation of main tunnel are monitored, and the structural internal force is calculated to obtain the structural response and its variation law of the main tunnel. The study results show that: (1) The construction process can be divided according to external load and structural system, and each working condition has obvious different response. (2) The internal forces of shield launching and receiving end are mainly affected by the shield jacking force and the external grouting load, which mainly affects the cutting side; the internal force increment during the cutting process reaches 10%～20%, and that induced by the grouting pressure reaches 50%. (3) The axial force increment of each ring and inner support is below 200 kN, the axial force loss caused by the breakthrough location can be shared by the remaining positions, and the breakthrough location does not require a special overload design.