盾构法与浅埋暗挖法结合建造地铁车站关键技术

盾构先行条件下拓展地铁车站,可以解决目前区间盾构施工和车站施工衔接的难题,提高盾构设备的效率,降低工程造价,充分发挥盾构法的施工速度快、距离长、质量高等优势,从而提高全线的工程建设速度,优化整体工程筹划。本文在盾构法与浅埋暗挖法结合建造地铁车站综合技术前期研究工作的基础上,采用数值模拟、节点模型试验和理论分析等方法对关键技术进行进一步深入细致的研究,主要工作及研究成果如下：(1)对盾构法与浅埋暗挖法结合建造地铁车站施工过程中站厅隧道二衬的两种施作时机进行了三维数值模拟,从隧道结构受力和地表沉降两方面进行了对比分析,结果表明站厅隧道二衬必须在横通道开挖之前施作好。(2)采用壳-弹簧-接触模型对管片结构进行数值模拟,考虑盾构管片之间的环向连接和管片环之间的纵向连接、以及管片结构与围岩的共同作用,从管片结构受力与变形、环向螺栓与纵向螺栓受力、管片接缝变形等方面深入研究了管片结构开口状态在车站拓展施工过程中的稳定性,同时对柱-预应力支撑体系的有效性进行了详细的受力和变形分析。结果表明：车站施工过程中,盾构隧道有整体向站厅隧道中心水平移动的趋势,垂直方向几乎不动,且横通道部位管片结构的水平位移大于塔柱部位,这造成横通道部位保留管片与塔柱部位整环管片之间的纵向螺栓受剪,部分螺栓甚至超过抗剪承载力设计值。盾构隧道的形状改变表现为水平方向相对发散,垂直方向相对收敛,有变成类似“扁平状”椭圆的趋势,从而使管片间接缝张开,这造成环向螺栓受拉,临近开口部位接缝的部分螺栓甚至超过抗拉承载力设计值。但是,通过柱-预应力索的支撑体系,这些趋势均得到有效控制,结构整体受力满足稳定性及承载力要求。(3)采用1：1的节点模型试验对开口环管片与车站主体结构连接节点进行了实验室试验,研究了节点的受力、变形及破坏形态,定量评价了节点的安全性与稳定性。结果表明：从受力角度来说,节点有足够的安全度；从变形角度来说,开口环管片与车站主体结构的节点连接应采用在管片内预埋钢筋接驳器的连接方式。
工业羊毛毡
Expanding metro station under shield running tunnel, can solve the contradiction of construction time between shield tunnel sections and adjoining stations, improve the efficiency of shield machine, reduce the project cost, fully play the advantages of shield tunneling on speed, long distance, and quality, thereby it will enhance the speed of the construction work in the whole line and optimize the whole project planning.Based on the preliminary research on schemes of constructing metro station by shield tunneling method combined with mining method, the construction scheme and key technologies were further studied in this paper by the research methods including numerical simulation, joint model test, and theoretical analysis. The main work and the achievement are as follows:(1) For the different construction time of secondary lining in station tunnel in the construction process of metro station by shield tunneling method combined with mining method, two kinds of construction schemes were put forwarded. The two construction schemes were simulated by three-dimension numerical method, and the internal force of the tunnel structure and the surface displacement were compared and analyzed. The results indicate that secondary lining in station tunnel must be constructed before excavating cross aisles.(2) Shield lining segments were simulated by the shell-spring-contact model, which can consider the hoop connection between segments and the longitudinal connection between segment rings. The stability of shield lining segments in the construction process were deeply researched by the aspects of the force and deformation of segments, the force of hoop bolts between segments and longitudinal bolts between segment rings, and the deformation of segment joints. The results indicate that the conventional designed segments meet the requirements in the construction process, only the force of part of ring bolts between segments and lengthways bolts between segment rings exceed the required carrying capacity, so the strength grade of the bolts at these locations should be improved.(3) The joints between segments and main structure of the station were studied by the 1:1 scale joint model test. The force, deformation, and damage patterns of the joints were studied, and the security and stability of joints were evaluated quantificationally. The results indicate that the joints are safe considered the force. The joint connection method of embedding steel connecting device in the segments should be used to connect segments and main structure of the station