挡土墙抗滑键抗滑作用研究综述

Research review on slide-resistance of shear key in retaining walls

基于国内外挡土墙抗滑键的研究成果,讨论了挡土墙设键对提高抗滑稳定性的影响,介绍了抗滑键作用机理及国内外抗滑键设计计算方法。各抗滑键设计方法差别较大,多数在底板中部或墙踵附近设键,但现场观测却发现正常工作荷载下键设在底板中部时键前被动土压力远小于设计预想,而在墙趾设键的抗滑作用则得到现场观测和模型试验的验证。基于对抗滑力仅与地基土抗剪强度有关的理解,根据传统的极限平衡法推导了墙趾设键挡土墙的抗滑稳定计算公式,该公式与《水工挡土墙设计规范》中底板向填土方向落深倾斜的抗滑稳定计算公式本质一致。对于护岸挡土墙,在墙趾设键可相应抬高底板,改善基础应力,还可起到改善基底扬压力和防冲作用,因此在护岸工程中得到广泛应用。

Based on the domestic and foreign research on retaining walls with shear key, the influence of shear key on improving sliding resistance stability of retaining walls is discussed.The mechanism of shear key and its design calculation methods at home and abroad are presented.There are large differences among different key design methods, most of the methods recommend setting shear key at the wall heel or middle of bottom plate.However, field observation found that the passive earth pressure in front of the key that is set at the middle of bottom plate under normal working loads is much less than the design expectation, while the effect of setting shear key at wall toe is verified by field observation and model tests.Based on the understanding that the anti-sliding force is only related to the shear strength of foundation soil, an anti-sliding stability formula for retaining wall with key at toe is deduced according to limit equilibrium method, and this formula is consistent with the anti-sliding stability formula of the bottom slab inclined to the filling direction proposed in Design Specification for Hydraulic Retaining Wall.For the retaining wall of revetment, the key located at wall toe can not only elevate the bottom plate and improve the foundation stress, but also alleviate base uplift pressure and improve the scour resistance, so it is widely used in the revetment engineering.