采空区临界安全顶板预测的厚度折减法

借鉴强度折减法计算边坡安全系数的思路，提出采空区安全顶板预测的厚度折减法.不断调整顶板厚度，直到其达到临界破坏状态，此时对应的顶板厚度即为安全顶板厚度.当顶板达到临界状态时，其位移将发生突变，计算不收敛，因此，将静力平衡方程组是否有解、计算是否收敛作为顶板破坏的标准.采用同时考虑拉伸和剪切破坏的Mohr-Coulomb准则，对某一采空区顶板安全厚度进行预测，并对采空区周围的应力和变形进行分析，结果表明：当采空区跨度分别为4，7，10，15，20，25 m时，顶板安全厚度为2.1，5.2，9.2，12.3，16.6，22.9 m；采空区跨度较小时，塑性区范围较小，顶板主要破坏形式为冲切破坏；随着跨度的增大，塑性区面积增加，破坏形式转变为垮落；当顶板发生破坏时，计算的不平衡力无法收敛，位移不断发展，位移最大值区域位于采空区正上部.

The thickness reduction method in forecasting the critical safety roof thickness of gob area

According to the idea of slope safety factor calculated by the method of strength reduction,the thickness reduction method was proposed to forecast the safety roof thickness of gob area.In the procedure of thickness reduction method,the roof thickness was reduced gradually until it reached the critical failure state,which marked the minimum safety thickness.If roof reached the critical failure state,displacement of the grid in the roof would mutate,and the calculation would be divergent.So whether or not th...