深孔落矿破顶层厚度综合确定方法及应用

Comprehensive determination method of blasting-roof thickness in deep hole mining and its application

针对深孔落矿破顶层厚度依赖经验判定的问题,运用塑性极限分析法计算破顶层临界破坏时所受外力功和内力功,基于虚功原理,推导得到5种典型边界条件下破顶层极限承载表达式。通过Surpac-Flac3D数值转换建模、爆破载荷等效、自定义编程等操作,建立获取破顶层动力响应特征的数值模拟技术。由此,提出基于力学计算与数值模拟分析的破顶层厚度综合确定方法。以某矿VCR法试验采场为应用对象,通过推导的极限承载表达式确定其最小破顶厚度为4.7 m,据此开展不同破顶厚度工况的数值模拟,结合应力分布特征、塑性区演化状态及安全率计算等分析,综合确定采场安全破顶厚度为7 m。研究为深孔落矿破顶层厚度的确定提供了客观可行的手段。

Aiming at the problem that the blasting-roof thickness was highly depended by experiences in deep hole mining, the plastic bearing method was used for calculating the external work and internal work of blasting-roof under the limit failure state. Based on the virtual work principle, the limit bearing equation of blasting-roof under typical five boundary conditions were derived. By using the Surpac-Flac3 D numerical modeling, the equivalent blast load calculation and the custom programming, a numerical simulation technique for obtaining dynamic response characteristics of blasting-roof was proposed. Accordingly, an integrate method for determining blasting-roof thickness was proposed. Taking a VCR test stope as the application case, the minimum blasting-roof thickness was calculated as 4.7 m using the derived equation. Based on that, the numerical simulations under different blasting-roof thickness condition were carried out. Through analysis of stress distribution, plastic zone evolution and safety factor calculation, the safe blasting-roof thickness was comprehensively determined as 7 m. The research provides an feasible tool for determining the blasting-roof thickness in deep hole mining.