土钉墙中土压力探究

Investigation into the Earth Pressure within Soil Nailing Walls

土钉墙喷射混凝土面层上受到的土压力大多假设为Rankine主动土压力,但在实际方案中面层却设计很薄,似乎无法承受假定的土压力,这里存在矛盾。文章采用数值实验方法,结合实际工程,对土钉墙面层上受到的土压力、土体内应力在基坑开挖过程的变化进行了评估。分析结果表明,土钉墙面层受到的计算土压力远小于Rankine主动土压力,面层的挡土作用很小。文中提出了在基坑工程等临时性工程中,建议钢筋网加喷射混凝土这样的传统面层改用防水牛津布或彩条帆布等柔性材料来替代,这将一方面发挥面层的作用,另一方面节约投资和减少土钉墙对地下空间产生的不利影响。

The shotcrete facing of soil nailing walls is often assumed to be imposed on by the Rankine＇ s active pressure, but its thickness tends to be designed almost too thin to bear such a big pressure, so the assumed condition is inconsistent with that of the facing in design. By the numerical experiments in deep excavation as well as case studies, the pressure imposed on the facing of soil nailing walls and soil stresses during excavation are explored and estimated in this paper. The analytical results indicate that the lateral earth pressure is the facing subjected to much less than the value determined by Rankine＇ s theory. Its earth-retaining function could be very limited and even neglected. It is recommended that in the provisional engineering such as deep excavation, the flexible waterproof material, for example, canvas, should substitute for the conventional facing layer of steel net plus shotcrete in soil nailing walls to save money and to avoid the side effects on underground space while the functions of the facing layer are still kept.