基于剪应变增量的岩质边坡开挖卸荷深度判别

Judgment of Unloading Depth of Rocky Slope Excavation Based on Shear Strain Increment

鉴于确定卸荷破坏程度和深度是岩质边坡稳定性分析首先要解决的问题,基于卸荷岩体力学基本理论,提出以岩体剪应变增量确定卸荷分区的方法,将开挖后的岩体划分为剪切变形区、开挖扰动区和应力不变区,并以锦屏水电站缆机平台边坡为例,对开挖过程进行数值模拟计算,通过与卸荷量百分比法的对比分析,验证以剪应变增量为标准判别卸荷深度的合理性,同时表明卸荷破坏程度和深度与岩体结构密切相关,存在结构面的岩体比完整岩体卸荷破坏深度更大。

Determining the extent of unloading damage and depth is the first problem to solved for rocky slope stabili- ty analysis. Based on the basic theory of unloading rock mechanics, the rock shear strain increment was proposed as the method of unloading partition, and the excavated rock could be divided into shear deformation zone, disturbed zone and stress constant zone. Taking the cable-crane platform slope of Jinping hydropower station as an example, numerical cal- culation was used to simulate the process of rock excavation. Comparing with the method of unloading amount percent- age, the reasonableness of the shear strain increment method is verified. The results indicate that the destruction of ex- tent and depth of unloading was closely related to the rock structure; compared with intact rock, unloading could cause greater damage depth to rock containing structural plane.