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以西安地铁工程为背景,对穿越地裂缝带的地铁隧道在地裂缝活动时的变形特征进行了研究。在此基础上,对穿越地裂缝带的整体式地铁隧道的监测部位和监测方法提出了建议。通过对整体式大型物理模型试验结果的分析,认为当地裂缝活动时,在靠近地裂缝下盘3H范围内的隧道变形量较大,变形使下盘隧道顶部受拉,底部受压。位于上盘的隧道在全长范围内都有变形,并在隧道底部产生部分脱空现象,脱空区的长度与隧道的埋深、长度、土与隧道的刚度比等因素有关。当变形或脱空区长度超过隧道的允许变形值时,将引起隧道顶部混凝土的开裂,引发漏水等不良现象,影响隧道的安全运营。在对试验成果分析的基础上,提出整体式地铁隧道的安全监测内容应包括:1)地裂缝两侧隧道的相对垂直位错;2)隧道底部脱空区的长度;3)隧道结构的应力变化幅度。针对上述变形特征及监测内容,提出了监测点的合理布置范围及采用的监测方法。
Based on Xi’an metro project, the deformation characteristics of metro tunnel crossing ground fissure zone during ground fissure are studied. On this basis, suggestions are put forward for the monitoring sites and monitoring methods for monolithic subway tunnels crossing the fissure zone. Through the analysis of the test results of the large-scale physical model, it is considered that the deformation of the tunnel near the ground crack 3H within a range of 3H during the local crack activity is large, and the deformation causes the top of the footwall tunnel to be pulled and the bottom of the tunnel to be pressed. The tunnels located on the hanging wall all have deformation in the whole length, and some emptying occurs at the bottom of the tunnel. The length of the void area is related to the depth and length of the tunnel, the stiffness ratio between soil and tunnel, and other factors. When the length of deformation or void area exceeds the allowable deformation value of the tunnel, it will cause cracking of the concrete at the top of the tunnel and lead to unfavorable phenomena such as water leakage and affect the safe operation of the tunnel. Based on the analysis of test results, it is proposed that the content of safety monitoring for a monolithic subway tunnel should include: 1) the relative vertical dislocation of the tunnels on both sides of the ground fissure; 2) the length of the void area at the bottom of the tunnel; 3) the stress of the tunnel structure The rate of change. According to the above deformation characteristics and monitoring contents, the reasonable layout range of monitoring points and the monitoring methods adopted are put forward.