盾构隧道管片设计若干问题研究与探讨

研究目的:目前盾构隧道管片设计的随意性较大,计算方法缺少相应的理论支撑,计算模型的选取无法体现管片的实际受力情况,无法体现地层与衬砌结构的相互作用,计算参数的取值与实际情况出入较大等。为了进一步加强管片结构设计的准确性与可靠性,对管片设计中涉及的一些主要问题进行研究。研究结论:通过分析得出,对于管片结构,应该采用梁—弹簧模型进行受力分析;管片结构上受到的水压力应按径向加载,隧道拱底反力应取浮力与竖向荷载的较大值,管片与地层的相互作用应通过管片四周设置的径向与切向土弹簧来实现;采用地层应力释放系数来模拟盾构施工对周围地层的扰动效应,得出应利用浆液的最小屈服强度控制盾尾后方隧道的上浮趋势。

Study and Discussion on the Issues about Segment Design of Shield Tunnel

Research purposes:In view of the relatively obvious randomness of segment design,such as the calculation method is lack of corresponding theoretic support,the calculation mode adopted can not reflect the actual force conditions of segment,the interaction between formation and segment can not be embodied,and obvious deviation dose exist between calculation parameters and actual situation,in order to enforce the reliability and accuracy of segment design,further study of some main issues related is required. Research conclusions:Through comparison and analysis,as for lining structure,the beam-spring mode should be adopted in stress analysis.The load direction of groundwater pressure should align with tunnel radius,reaction force at the arch bottom should be determined through the comparison between buoyancy and the vertical total load,and the interaction between ground and segment should be modeled by radial and tangential springs.Furthermore,the dimension of sealing gasket in segment joints should be determined by numerical simulation,the release coefficient of ground stress can be adopted to simulate the disturbance of surrounding formation due to tunneling,and the control of the upward movement of tunnel lining should be realized by the minimum shield stress of grout.