地下开采上覆巨厚岩层断裂机制研究

STUDY ON FRACTURE MECHANISM OF OVERLYING SUPER-THICK ROCK STRATUM IN UNDERGROUND MINING

以巨厚岩浆岩下采矿工程为背景,运用弹性基础厚板理论研究巨厚岩浆岩下煤层不同开采阶段对上覆岩层的影响以及岩浆岩变形规律与破坏模式。研究结果表明:随着工作面的推进,覆岩逐渐垮落,岩浆岩下方开始出现离层;当作面推进到一定长度时,巨厚岩浆岩层的上表面的边缘中点处应力达到岩体抗拉强度而破裂;随着工作面推进长度的加大,中面长边中心点由于剪应力达到岩体的抗剪切强度而发生剪破坏,随后岩层的上表面的中点处应力达到岩体强度产生拉破裂,并向四周扩展,最后中面短边中心点由于剪切作用发生破坏。当工作面宽度加大时,开始出现破裂的工作面推进长度减小。

The key stratum controls the deformation and failure modes of the mining rock mass. Based on mining condition which is covered by super-thick magmatic stratum, failure conditions and failure modes of magmatic stratum are studied by means of analytical solution--theory of thick plate rested on elastic foundation when mining is carried out in different stages. It indicates that overlying strata gradually break down and separation appears under the magmatic rock when the mining length increases. Tensile fractures could occur in the midpoint of the boundary in top side when mining at certain distance, then shear fracture could occur in the midpoint of the long sides in the central plan when the length of work face increases. After that, tensile fracture could occur in the midpoint of the up side and propagate to all round sides gradually if the length of work face keeps on increasing. At last, midpoint of the short boundary in the central plan fractures because of the shear stress along the thickness direction. The working face mining distance can decrease when fracture occurs and the mining width increases.