盾构下穿高速公路扶壁式挡土墙的变形分析

Analysis of Deformation Characteristics of the Buttressed Retaining Wall for Subway Shield Undercrossing Highway

研究目的:地铁盾构施工土体挖除、管片和二衬设置对土层的扰动会导致地表挡墙的变形,尤其是挡墙沉降和倾斜,对上部公路的运营产生不利影响。论文用Midas/GTS模拟北京地铁6号线下穿通燕高速公路北皇木厂桥段,分析采用盾构法先后施工左右线隧道引起的桥间路基扶壁式挡墙的变形变化特征。研究结论:(1)挡墙竖向位移变形与挡墙到两侧桥台距离之间呈现"中间大、两边小"的抛物线型变化趋势;(2)挡墙沉降的大部分产生在先施工左线过程中,后施工右线中则较小,说明挡墙沉降主要发生在第一次盾构穿越施工时,因此在第一次施工过程中应该适当减小推进长度;(3)挡墙变形与盾构隧道的位置距离呈负相关的关系,挡墙的倾斜度表现为盾构施工正上方时倾斜度出现极值,同截面极值点两侧逐渐减小;(4)该研究成果可为地铁盾构穿越上部挡墙结构安全性评估工作提供指导。

Research purposes： Excavation, segment and second line set of soil in subway shield construction can lead to the surface deformation of the retaining wall, retaining wall subsidence and incline, especially for the operation of upper highway. Midas/GTS is used to simulate Beijing metro line 6 through Beihuangmuchang Qiao section of Tong Yan highway, the deformation characteristics of subgrade buttressed retaining wall between bridge and subgrade is analyzed by the tunnel shield construction around line.Research conclusions： （ 1 ） The vertical displacement deformation of the retaining wall and the distance between retaining wall and the abutment present the parabolic trend of ＂ big in the middle and small in the edge＂. （2） The settlement of retaining wall is produced most in the left line of earlier process of the construction, the later construction in the right line is small, it seems that the settlement of retaining wall is mainly produced in the first shield construction. Therefore, we should reduce the advance appropriate length in the process of construction for the first time. （3）The deformation of the retaining wall and the location distance of the shield tunnel presented negative correlation, the slope of retaining wall is found that above the shield construction it turns out gradient extremum, in the both sides of extreme value point it decrease gradually. （4） The results of the paper can be used to provide guidance for safety assessmentwork when subway shield tunnel cross the upper retaining wall structure.