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地裂缝是西安典型的地质灾害,对地铁建设造成很大威胁,引起了社会各界的广泛关注。进行地裂缝活动引起地铁隧道的变形破坏特征研究,尤其是针对性地研究地裂缝与地铁隧道在空间交汇处的运移特点及隧道结构的抗裂设计参数具有重要的理论和现实意义。在分析西安地裂缝基本特征的基础上,以地铁5号线隧道工程穿越地裂缝情况为具体研究背景,详细论述了与隧道相交处地裂缝的发育特征,揭示了地裂缝活动造成的地表及剖面上的破坏特点,并分析了现阶段沿线地裂缝的活动速率,确定了在空间上隧道与地裂缝的实际交汇位置。根据地裂缝年活动速率监测资料,对地铁设计使用期内隧道与地裂缝交汇处的最大垂直位移量进行了预测,并在此基础上结合地裂缝与隧道的夹角及其倾角,根据空间几何关系换算得出隧道结构三维抗裂预留位移参数,最后通过数值模拟分析对分段隧道扩大断面的适应性进行了验证。研究结果表明:与地铁斜交的地裂缝活动会引起相邻分段隧道结构产生竖向位错、横向扭曲及轴向拉伸等变形破坏;上盘隧道净空量满足预留设计要求;该研究成果可为在地裂缝活动环境下西安地铁隧道的结构设防措施提供参考与指导。
Ground fissures are typical geological disasters in Xi’an, posing a great threat to the subway construction and arousing widespread concern in the community. It is of great theoretical and practical significance to study the characteristics of deformation and failure of metro tunnels in the process of ground fissures. Especially, it is of great theoretical and practical significance to study the transport characteristics of ground fissures and metro tunnels in space and the crack resistance design parameters of tunnel structures. Based on the analysis of the basic characteristics of ground fissures in Xi’an and based on the concrete research background of the tunnel fissures along the subway line 5, the development characteristics of fissures at the intersection with the tunnel are discussed in detail. The surface and section And analyzes the movement rate of ground fissures along the current stage, confirming the actual location of the intersection of tunnel and ground fissure in space. According to the monitoring data of annual rate of ground fissure movement, the maximum vertical displacement of the intersection of tunnel and ground fissure during the design and service life of the subway is predicted, and on the basis of the angle and angle between the ground fissure and the tunnel, according to the spatial geometry The displacement parameters of three-dimensional anti-cracking of the tunnel structure are obtained through the conversion. Finally, the adaptability of the enlarged section of the sectioned tunnel is verified by numerical simulation. The results show that the ground fissure activities that intersect with the subway will cause vertical dislocations, lateral distortions and axial tensile deformation of the adjacent segmented tunnel structures. The clearance of the tunnels on the upper plateau meets the requirements of the reserve design. The results can provide reference and guidance for the structural fortification of Xi’an subway tunnel under the active ground fissure.