基于弹性理论的软弱顺层岩质边坡受采动影响研究

在有软弱顺层边坡地形中进行采矿通常会引起边坡稳定性变化,因而研究此类边坡在受采动沉陷的影响在地质问题中是尤为重要的。首先利用关键层理论概念分析得到,在含有软弱结构层的岩质斜坡受到采动或开挖影响时,软弱结构层将和关键层同步变形而与上部岩质斜坡产生离层,形成悬臂结构。再根据弹性力学理论计算出岩质斜坡的极限悬臂长度以及断裂长度。最后利用实际矿山地质进行稳定性判断。结果表明,随着工作面的不断推进,采动影响下的离层距离变大,岩质坡体最大拉应力将沿着坡表面向前移动并且逐渐增高,最大拉应力点与发生离层点的距离X_(max)却急速减小,当离层距离达到l_(max)时,最大拉应力达将到坡体抗拉强度,岩质坡体断裂,此时岩体断裂长度达到l_(max)+X_(max);通过实际矿山工程算例得到,当坡顶上离层距离达到6.88 m时,若下方采空区继续推进增加,则上方坡体将产生断裂形成滑坡。

On the effect of the mining activities on the rock slope with the soft interlayers in view of the elasticity theory

Based on the basic principles of the key layer theory, this paper has first of all made an analysis of the influence of the mining and excavation activities on the stability of the rock slope with the soft structure layers. The stability of the slope has been usually influenced by the mining activities under the weak bedding slope,which may lead to the geological disasters,such as mining floor subsidence or part or total area collapse. In such a situation,the weak geo-structural layers may result in the deformation and even split of the key layers from the upper rock slopes to form somewhat cantilever structure. And,in more serious situations, the rock mass may turn to get suspended and lead to the cantilever structure. Therefore,it is of extreme importance to know the actual seriousness of what the slope would have to experience in such circumstances. For the said purpose,it is first of all necessary to solve the cantilever length. And,then,it is needed to work out the limit cantilever length and the fracture length of the rock slope based on the elasticity mechanics theory. And, finally,it is also necessary to verify and determine the stability limit of the slope by applying to the actual mining geological case. The result of our study proves that: with the continuous advancing of the working face or faces,under the influence of mining,the maximum separation stress of the rock slope is surely to move along the broken surface and gradually increase,while the distance (xmax) between the point of maximum tensile stress and the point of separation decreases in time rapidly. When the separation distance reaches lmax,the maximum tensile stress may reach the slope tensile strength and make the rock slope broken. In such a situation,the broken length is likely to reach lmax + xmax. If so, the slanting distance of the actual mining project from the top of the slope may reach 6. 88 m. At the same time,if the lower gob would move forward continuously,the upper slope may turn to be fractured while the stress of the rock mass may tend to deform due to the fracture and lead to the abrupt change of stability of sloping body and even to the risk of landslides.