广西合山煤田浅埋煤层采空区塌陷机理数值分析

Numerical Analysis on the Mechanism of Mining Collapse in Shallow Seam of Heshan Coal Field,Guangxi

针对广西合山煤田煤炭资源的枯竭,煤层开采引发的地面塌陷日益增多,地质灾害问题突出的现状,以煤田上塘矿区中南部的4个浅埋采空区为研究对象,在野外调查的基础上,利用离散元法建立三维数值模型,进行采空区顶板和地表的变形与应力分析,探讨了采空塌陷机理模式。分析结果表明:①采空区规模直接决定了地表变形程度,表土层厚度的影响作用是双向的;②地表水平移动极大值向下山方向偏移,下山方向顶板覆岩更易断裂和垮落;③采空区上覆岩层发育"两带",主要破坏形式为拉张破坏和剪切破坏;④浅埋采空塌陷的形成可归纳为开始、发展、贯通和稳定4个阶段,不同阶段均有典型的变形和受力表征。

In view of depletion of coal resources, the increase of ground subsidence caused by mining and geological dis- asters up in Guangxi Heshan Coal Seam,four shallow goafs in south-central part of Shangtang Mine are listed as research object to analyze the deformation and stress of roof and surface in mined-out area by building the three-dimensional numerical model with discrete element method,based on field investigation. The mechanism model of mining subsidence is discussed. The re- suits show that： （2）The goaf scale directly determines the degree of surface deformation, and the influence of surface soil＇s thickness is double acting;（3） Maximum of horizontal surface movement shift to downhill, and roof rock at downhill more easily results in breakage and caving;（4） ＂two zones＂ have developed at the goaf overburden, and its main failure mode are tensile failure and shear failure ; （5）The formation of shallow mining collapse is summarized as four stages ： beginning, development, perforation and stable. Each stage has its typical characterization of deformation and stress.