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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 the roof thickness and the critical span above the empty area, this paper takes a group of mined-out area of an open-pit iron mine as an example, obtains the mechanical parameters of roof rock mass based on the rock mechanics parameters measured by on-site sampling, Nirvana formula method, thick-to-span ratio method, structural mechanics beam theory, flat beam theory method to calculate it. At the same time, the author uses RFPA numerical simulation method to simulate the damage and collapse process of the roof, and calculates the relationship between the roof safety thickness and the critical span when the initial damage and collapse of the roof. The result of K.B.Rubayne et al. Formula is the closest to the initial value of RFPA calculated roof damage, and the ratio can be regarded as the safety factor obtained from numerical simulation. Thus, the critical thickness of the top plate calculated by K.B. Reubneh et al. Formula retains a large safety factor. Based on the RFPA numerical simulation, the safety factor can be calculated and has a wider applicability.