具有下伏软弱层的矿山边坡开挖安全厚度研究

Safety thickness study of slopes with weak planes

具有下伏软弱结构面的矿山边坡开挖时 ,在软弱结构面上应保留的最小岩体厚度 ,即“边坡开挖安全厚度”,是边坡设计的控制性参数。本文以攀枝花石灰石矿为例 ,根据边坡的失稳机制分析 ,简化、抽象出边坡失稳的刚体极限平衡模型 ;在此基础上 ,导出了边坡开挖安全厚度的计算公式。

As there exists a weak plane or soft interlayer developing nearly parallel to slope surface,a slope often fails by cutting through the intact rock mass at the place with the smallest thickness between the bottom of the cutting slope and the weak plane.On this occasion,the smallest thickness,called as limit safety thickness for slope cutting,is an important parameter for slope designing in open pit mines or other slope engineering.In this paper,the authors present a model based on a rigid block and limit equilibrium theory to describe the limit stability status,from which an equation of the limit safety thickness is obtained.The effects of some factors on the safety thickness are discussed.The results show that the strength of the intact rock mass overlying the weak plane has special importance on the slope stability.Except for a careful design considering the limit safety thickness,this part should be protected strictly from being destroyed or damaged during excavation and explosion.