空区顶板安全厚度和临界跨度确定的数值模拟

Numerical Simulation for Determining the Safe Roof Thickness and Critical Goaf Span

为了确定空区上方顶板厚度和临界跨度之间的关系,本文以某露天铁矿采空区群为工程实例,通过现场取样测定的岩石力学参数为基础获得顶板岩体力学参数,采用K.B.鲁别涅依他公式法、厚跨比法、结构力学梁理论、平板梁理论法对其进行计算。同时,作者利用RFPA数值模拟方法对空区顶板的损伤及垮塌过程进行数值模拟,计算空区顶板发生初始损伤和失稳垮塌时顶板安全厚度与临界跨度之间的关系。K.B.鲁别涅依他公式法所得结果与RFPA计算的顶板发生初始损伤时的数值结果最为接近,两者的比值可认为是从数值模拟获得的安全系数。由此可见,由K.B.鲁别涅依他公式法计算的顶板临界厚度保留了很大的安全系数,基于RFPA的数值模拟可以计算该安全系数,具有更为广泛的适用性。

In order to determine the relationship between goal roof thickness and critical span, an iron ore goaf is taken as an engineering instance. The rock mass mechanical parameters are obtained from the mechanical experiments of rock specimens sampled in situ. The relationship between the safe roof thickness and the critical goal span is determinined according to K. B. Lu Peinie equation, ratio of thickness and span equation, structure mechanics of girder and plate beam equation. Meanwhile, the damage and failure process of goaf roof is simulated by RFPA numerical simulation program. The rela-tionship between the safe roof thickness and the critical goal span is determined, respectively, when the initial damage and instability of goal roof are adopted as the criteria. The values predicted with K. B. Lu Peinie equation are most close to the numerical ones when the damage of roof begians. The ratio be-tween them can be considered as a safety factor obtained from the numerical simulations. As it shows, it is kept a large safety factor by the critical roof thickness which is calculated by K. B. Lu Peinie equation. The numerical simulation with RFPA could obtain this safety factor, and it may have more extensive applicability.