【作者】 刘妮娜；

【导师】 门玉明；

【作者基本信息】 长安大学 ， 地质工程， 2010， 博士

【摘要】 西安地裂缝自1959年首次发现以来,已对西安市的城市建设和人民生活造成了极大的影响,并对在建和拟建的多条地铁线路构成了威胁。在目前已经探明的十四条地裂缝中,有多条与正在建设中的西安地铁1号、2号线相交。西安地裂缝在未来地铁建设及运营期间的活动无疑会影响到西安地铁的安全性。由于西安市位于高烈度地震区,已有的震害研究表明,地铁结构作为城市的生命线工程一旦遭受地震破坏,将会给地震应急以及震后修复工作带来极大的困难。如何保证西安地铁在强震作用下的安全,同样也是地铁建设中的重要课题,因此,在西安市这一特殊的工程地质环境下建造地铁是一个全新的重大工程难题,学术界和工程界均对此高度关注。本文以西安市重大工程—西安地铁穿越地裂缝活动带的防灾措施为工程研究背景和依托,以地铁沿线地裂缝在地震动力荷载作用下的活动特征及西安地铁隧道在这一特殊工程地质条件下的动力反应特征及土与地下铁道的地震动力相互作用为研究对象,采用模型试验、数值模拟、理论分析相结合的方法对动力荷载作用下西安地裂缝的活动特征,地铁隧道在动力荷载作用及地裂缝活动状态下的动力反应进行了系统的研究。基于对地裂缝运动及其对地下结构破坏规律的认识,建立了地震动力荷载作用下的地裂缝场地动力试验模型。试验表明,在地震荷载作用下,隐伏地裂缝的上覆土层会产生开裂,出露地表且裂缝宽度增加,并在原有地裂缝附近引起与之相交的次生裂缝,地震荷载作用引起的地裂缝开合,使其成为深部土体向上运动的通道。论文首次进行了地裂缝环境下地铁隧道地震动力振动台模型试验,以相似原理为依据,建立了基于重力失真模型的黄土自由场地环境下盾构隧道及马蹄形隧道地震动力作用振动台试验模型。通过试验证明地铁隧道在动力荷载作用下的运动加速度比其周围土体的动力加速度大；地铁隧道在动力荷载作用下所产生的动土压力相比于振动前后土压力要增加许多,所以在地铁结构设计中对于动土压力及侧向土压力应引起重视；动力荷载作用下盾构地铁隧道底部的正应力较大。通过试验研究,发现由于地裂缝南北两盘的不均匀沉降,地裂缝邻近部位的地铁隧道应力出现增大现象。当地裂缝场地中采用柔性分段式地铁隧道穿越时,其地铁隧道各段的动力反应具有一定的相对独立性,且在地裂缝区域没有出现应力剧增的现象,据此在工程中建议采用柔性分段接头穿越地裂缝区域。论文还基于有限元理论建立了以Marc为分析平台的有限元数值分析模型,对西安地铁中采用的典型隧道形式进行了地震荷载作用下的动力特征分析及与地裂缝运动耦合时的地铁隧道动力分析；研究认为：地震动力荷载作用下地铁隧道结构所受的剪应力较大,工程中应该进行相应的考虑；动加速度和主应力的最大值产生于隧道结构的底部,同时在地铁隧道内部各点的累积变形大于隧道外部各点的累积变形；当地裂缝场地南盘相对于北盘下沉时,将在分段马蹄形隧道各分段处产生摩擦作用且在各连接部位产生压应力,同时在隧道的两侧壁和各连接处产生较大的剪应力。更多还原

【Abstract】 Since discovered in 1959, the ground fissures in Xi’an have caused serious damaged to the development of the city and daily life of the citizens. The ground fissures influensed the metro tunnel system of the city. There are totally 14 ground fissures in Xi’an; most of them have junctions with the 1st and 2nd line of the metro system. The activities of the ground fissures will have closely relationship with the safety of the metro tunnel system. The Xi’an is a city has potential of earthquake activities for its geology characteries, with the research from the history earthquake activities, when the life lines of the city as the metro system damaged by the earthquake activities, it was hard to recoverd and caused disters to the emergency system. It is a difficult research topic for building metro system in the ground fissures area, so lots of attentions paied in the research and engineering field.Based on the key work as the Xi’an metro system across the ground fissures, the dissertation focused on the soil and metro tunnel dynamic interactions in the ground fissures area. The field survey, the shakin gtable test & the FME method were used in the research for the dynamic characters of the ground fissures and the metro tunnels. The different metro tunnels as shield tunnel, the horse shoe shape tunnel were set up models in the shakeing table test and FME.Based on the ground fissures movements and its damaged to the underground structures, the shaking table model test of the ground fissures had set up. The result showed that the soil covered on the ground fissures would break and the fissure would be longth and wideth and there would have some small fissures near the original one. The close and open of the fissure in the dynamic activities caused a way to the soil which can lift from the bottom along the fissure.There were models of the shield tunnel and horse shoe shape tunnel for the shaking table. For the results of the shaking table tsets, conclusions as these wre got, the acceleration of the tunnel is bigger than the adjact soil; the dynamic soil pressure is serious to the tunnel in earthquake activities; the bottom of the tunnel has bigger stress than other parts of the tunnel.The shakin gtable test of the metro tunnel locates in the ground fissures area got that for the ununiform settlement in the south and north parts of the ground fissures, the stress of the tunnel close to the fissure were bigger than that far away the fissures. When the soft injunction used in the tunnel, the bigger stress decreased, and the differents parts of the tunnel move separately.The FEM model for the shield tunnel and horseshoe shape tunnel were set in the Marc, the study showed that the shear stress of the tunnel is bigger, for the design should consider the shear stress; the bottom of the tunnels have bigger dynamic acceleration and main stress. When the south part to the fissure was settle, there are friction, pressure and shear stress in the junction part of the tunnel.更多还原