土钉支护工作性能的应力路径分析

Stress path analysis on working behaviors of soil nailing

采用数值方法,从土体应力路径的角度研究了土钉支护的工作性能和加固机理。结果显示:应力路径分析方法能够很好地反应随着基坑开挖、支护工序一步步推进,土体应力不断转移叠加的力学响应过程。土钉的应力扩散和应力分担作用使得土钉头部和中部位置土体的切向应力减小、法向应力增大,应力路径由垂直逼近强度包线方向转为基本平行于强度包线方向;土钉的应力传递作用又将钉头部位土体的应力转移至钉尾深部的土体。整个支护系统通过土钉的应力扩散、应力分担和应力传递这3大作用不仅大大降低了钉头部位土体的应力水平,而且明显改善了它的应力状态,同时又有效地调动了钉尾深部土体自身的强度。

Using the numerical method, the reinforcement mechanism of soil-nailing based on stress path analysis was studied. It was shown that the stress path method could effectively represent the mechanical response of soil mass in accordance with the working procedure of excavation and supporting. The stress dispersion and sharing of nails caused the reduction in tangential stress and the increase in normal stress, and therefore it resulted in change of stress path of soil mass from vertical to parallel to the strength envelope. Furthermore, the stress transmission of nails from the forepart to the rearend of soil rendered its stress and strength level, that is the stress significantly falling at the forepart and the strength fully developing at the rearend.