考虑土拱效应的盾构隧道开挖面稳定性

Workface Stability of Shield Tunnel Considering Arching Effect

在考虑松动土体内的三维土拱效应和开挖土体与刀盘摩擦力的基础上,改进了传统的筒仓楔形体模型计算方法.结果表明:最小土压应力并不是传统方法假设的均匀分布形式,而是近似呈抛物线分布;土的黏聚力、内摩擦角、刀盘与松动土体间的摩擦角以及埋深等物理参数对其最小土压应力均有一定程度的影响;降低刀盘与开挖面土体间的摩擦角可以显著增加开挖面的极限稳定性.通过与模型试验结果和其他计算方法的对比分析,验证了本文计算方法的合理性.

The minimal earth pressure on the shield tunnel face can be calculated using a new method proposed in this paper.This method takes into account the arching effect in loosening soil and the friction between cutter and soil.It is found that the distribution of the minimal earth pressure is not uniform,which is assumed by the existing methods,but parabolic.The parameters,including soil cohesion,soil friction angle,the friction angle between cutter and soil and the cover-to-diameter ratio,have significant influence on the minimal earth pressure.The stability of workface can be enhanced by decreasing the friction angle between cutter and soil.Finally,the results of the proposed method agree quite well with those reported in other literatures based on the existing methods.