特厚复合顶板支护三维数值模拟研究

3D numerical simulation of extra-thick compound roof support

特厚复合顶板支护难度大,采用锚网索支护时经常会发生锚杆(索)破断或失效,极容易发生大面积冒顶事故,且其冒顶过程迅速、预兆不明显,较难预防。为了解决该问题,通过三维数值模拟和工程实例分析了其失稳机理,研究了支护锚索容易破断及冒顶过程迅速的原因。研究结果表明:锚杆(索)容易破断的主要原因是剪应力过大,容易失效的原因是锚固区处在围岩裂隙发育区或软弱岩层;特厚复合顶板一般都具有内部各岩层厚度较小、总厚度较大、岩性较差等特征;特厚复合顶板会发生突然冒顶的原因是其顶板中存在一层或数层相对较硬的岩层;最后,为特厚复合顶板支护提供了一些支护参数和支护建议,这为类似工程提供了参考依据。

The support of extra thick - compound roof is difficult and very easy to cause large area roof fall accidents. In the process of supporting, damage and fracture of bolt and anchor cable often appear. And the process of roof fall is very fast and lack of warning, which is more difficult to prevent. In order to solve the problem, based on the numerical simulation and engineering examples, this paper analyzed the instability mechanism and studied the causes for anchor cable damage and fast roof falling. The results are as follows ： the cause for anchor cable damage is the large shear stress ; the reason for support disability is that, the anchorage zone is located in the fractured zone of surrounding rock or soft rock strata ; extra - thick compound roof is usually of smaller single strata thickness, larger overall thickness and poor lithology ; the reason for the sudden roof caving of extra - thick compound roof is that there is one or more hard strata in the roof.