带翼缘板圆钢管顶进过程地表变形研究

采用带翼缘板圆钢管顶进形成地下管幕支护空间，相比传统的顶管工法具有诸多优点，已被用于建造城市地下空间.但由于翼缘板的存在，导致管周土压力分布复杂，顶进引起的地表变形与圆形顶管差异较大.基于此，在带翼缘板圆钢管管周土压力作用机理研究基础上，采用弹性力学Mindlin解推导出带翼缘板圆钢管顶进过程管周摩擦力引起的地表变形计算公式.基于沈阳地铁九号线奥体中心站暗挖段带翼缘板圆钢管顶进工程，采用Midas有限元分析软件对带翼缘板圆钢管顶进过程进行数值模拟计算.得出带翼缘板圆钢管顶进过程中，横截面地表变形呈“U”型沉降槽，纵截面监测点地表变形随顶管扰动逐渐增大，顶进截面超过监测面一节管长后地表变形趋于稳定；并分析了不同土体黏聚力、内摩擦角对顶进过程地表变形的影响.

Study on Ground Surface Settlement due to Pipe Jacking of Circular Steel Pipes with Flange Plates

Due to the advantages of the circular steel pipes with flange plates in forming underground support structures compared with the traditional pipe jacking method， it has already been used to construct urban underground spaces. However， due to the existing of the flange plates， the earth pressure around the pipe is complicated， thus the ground surface settlement during jacking process is quite different from that of the circular pipe. The effect of the earth pressure around the circular steel pipe with flange plate was studied and the ground deformation formula caused by the friction around the pipe during the jacking process was derived using the Mindlin solution based on elastic mechanics as well as the coordinate conversion theory. By taking the Olympic Sports Center Station of Shenyang Metro Line 9 as an example， the Midas finite element analysis software was used to simulate the jacking process of the circular steel pipes with flange plate. It is found that the cross-section ground surface becomes a “U”-shaped settlement groove. The surface settlement of the monitoring points at the longitudinal section gradually increases with the disturbance of the pipe jacking， and the ground deformation tends to be stable after the head of the jacking pipe exceeds the monitoring surface by the length of the pipe element. The influence of the soil cohesion and the internal friction angle on surface settlement during the jacking process was also analyzed.