琼州海峡隧道盾构对接冻土帷幕受力状态力学分析

Analysis on Mechanical Behavior of Frozen Soil Umbrella for Shield Junction in Qiongzhou Strait Tunnel

采用三维有限元的方法对冻结法在盾构对接施工地层加固中所形成的冻土帷幕的应力状态和变形进行分析与安全评价,分别探讨单排管与双排管2种不同冻结方案的情况。对于盾构对接施工中刀盘拆除情况进行了模拟,分别选取圆周方向上一次性拆除不同长度的刀盘,研究其对冻土帷幕应力强度、径向变形和主应力的影响。研究结果表明,利用冻结法加固盾构对接是可行的;双排管冻结方案相比单排管冻结方案,安全性上有很大提高;圆周方向一次性拆除刀盘的长度对冻土帷幕的各个指标影响较大。利用计算结果,可为盾构对接施工时冻结法地层加固提供参考依据。

The mechanical behavior and deformation of the frozen soil umbrella in shield junction under artificial freezing condition in Qiongzhou strait tunnel are studied by using three-dimensional finite element numerical simulation method. The simulation is conducted in different ways in order to make evaluations on two different freezing methods, i. e. , sin- gle-row-pipe freezing method and double-row-pipe freezing method. Great emphasis is put on the demolition of cutter head in shield junction. In the simulation, cutter head of different lengths in the circumferential direction is demolished, which would definitely affect the mechanical behavior and deformation of the frozen soil umbrella. The research demon- strates that the double-row-pipe freezing method is superior to the single-row-pipe freezing method in terms of safety. The length of cutter head demolished has great influence on the mechanical behavior and deformation of the frozen soil um- brella. The paper can provide reference for shield junction under soil freezing condition.