The progress of failure of mining developed cavern and its influence on the ground surface

从矿山安全和环境保护的角度出发，探讨采动采空区破坏对地表的影响条件、诱发采空区大规模破坏的条件以及防止采空区大规模破坏的最小充填量等问题，具有重要意义。为此，我们提出了一种基于岩石力学的弹塑性分析方法，使用有限元假设的洞穴已经通过了很长的时间，岩石的强度已经足够低。并将该方法应用于某矿山的大型洞室群。结果表明，地下洞室群的破坏将向地下洞室群上方发展约100 m，但不会影响地表。其次，为了明确上述条件，我们将该方法应用于平面下的多个等距洞室。在分析中，考虑了八种情况，通过改变洞室的深度，支柱的宽度和水平方向与垂直方向的应力比。因此，清除了以下内容。当洞室深度大于洞室高度的两倍，矿柱宽度大于洞室宽度的两倍时，破坏过程不影响地表。当应力比大于3且矿柱宽度大于2倍洞室宽度时，大规模破坏很少发生。这些结果仅来自8例病例的分析。因此，为了得到更一般的结果，我们必须研究更多的情况。

From the standpoint of safety and environment keeping in a mine, it is important to discuss what conditions make the failure of mining developed caverns affect the ground surface, what conditions induce large-scale failure of the caverns and what is the minimum volume of filling to prevent such failure. To do this based on rock mechanics, we proposed an elasto-plastic analysis method using FEM assuming that the caverns have passed very long time and the strength of rock has been lower enough. Then, we applied this method for the large caverns of a mine. As the results, it was cleared that the failure of the caverns will progress about 100m upper to the caverns but will not affect the ground surface. Next, in order to clear the conditions as mentioned above, we applied this method for the many equally separated caverns under a flat surface. In this analysis, eight cases set by changing the depth of the caverns, the width of pillars and the stress ratio of horizontal direction to vertical direction were considered. Consequently, the followings were cleared. The progress of the failure does not affect the surface when the depth of caverns is deeper than the twice of caverns' height and the width of the pillars is larger than the twice of caverns' width. Furthermore, the large-scale failure rarely occurs when the stress ratio is as large as three and the width of the pillars is larger than the twice of caverns' width. These results were derived from the analysis only for eight cases. Therefore, in order to get more general results, we must study for much more cases.