盾构近接隧道施工力学行为分析

在地下工程近接施工中，新建结构物的施工会改变既有结构物的受力状态，从而对既有结构物产生各种不利影响。由于新建结构物的受力模式不同于半无限体或无限体中修建单一洞室的一般状况，其初始应力场往往经过多次扰动，施工时将再次进行扰动，表现出极大的变异性。通过三维仿真计算，模拟了盾构机上作用3种不同推进力时对既有运营隧道变形和主应力的影响，以对是否加固既有运营地铁隧道给出建议，同时对最大推进力作用下随着盾构隧道的开挖对既有地铁隧道轨底倾斜度的影响进行了分析。分析计算得出的结论对于盾构隧道设计和施工有一定指导意义。

Analysis of mechanical action of shield driving for approaching excavation

In course of the approaching excavation of underground works,the construction of new structure will change the mechanics case of existing structure and brings some bad influence.At the same time,the mechanical mode of newly-built structure is not the same as that single cavern is excavated in the half-unbounded space.Its original stress field is disturbed by former time and time again,and once more by excavating of later.A project is taken into account in this paper.By the three-dimensional elastoplastic finite element analysis,results show whether we should reinforce the old tunnel or not,it gives the suggestion,as well as whether the shield driving influences the orbit pitch of the old tunnel.It also simulates three pressure on the shield machine and how to influence the distortion and the principal stress.Finally,it makes the conclusion that may instruct the design and the construction of the project.