边坡开挖卸荷松弛区的力学性质研究

开挖卸荷松弛区对边坡稳定性分析与防护加固工程设计具有重要的作用和影响,重点体现在松弛区的分布特征及松弛岩土的强度衰减效应。基于典型边坡的开挖模拟,研究其最大主应力增量及塑性区力学特征与分布规律,结果表明:边坡开挖应力调整引起的最大主应力增量的负值区与坡面塑性区的分布形态与发展规律吻合;基于边坡开挖卸荷松弛的基本力学原理,以开挖边坡应力张量增量的最大主应力分量增减变化作为开挖卸荷松弛区的划分标准,提出了接近开挖坡面的应力衰减塑性松驰区、远离开挖坡面的原岩应力区及介于两者之间的应力集聚弹性挤压区的三场确定方法。

Research on the mechanical character of relaxing zone of slopes due to excavation

The analysis for relaxing zone is very important for stability analysis and design of slopes,and it is difficult to confirm the boundary of relaxing zone because of excavation and to evaluate the reducing effect for strength parameters of rock or soil.Based on a typical case study by finite element analysis for excavation,the character of differential principal stress and yield zone are researched,the results show that: the distribution and development of the negative differential principal stress zone is almost the same as yield zone.In the end,according to the mechanical character of relaxing zone due to excavation,the change of differential principal stress tensor which is obtained by subtracting the stress tensors before and after excavation is used to confirm the range of relaxing zone;and then,stress attenuation plastic relaxing zone near excavation surface,original stress zone far from excavation surface and stress concentration elastic compressing zone between above two are partitioned.