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Kaizong Xia, Zhiwei Si, Congxin Chen, Xiaoshuang Li, Junpeng Zou, and Jiahao Yuan, Numerical and theoretical study of large-scale failure of strata overlying sublevel caving mines with steeply dipping discontinuities, Int. J. Miner. Metall. Mater., 31(2024), No. 8, pp.1799-1815. https://dx.doi.org/10.1007/s12613-024-2838-3
Kaizong Xia, Zhiwei Si, Congxin Chen, Xiaoshuang Li, Junpeng Zou, and Jiahao Yuan, Numerical and theoretical study of large-scale failure of strata overlying sublevel caving mines with steeply dipping discontinuities, Int. J. Miner. Metall. Mater., 31(2024), No. 8, pp.1799-1815. https://dx.doi.org/10.1007/s12613-024-2838-3
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陡倾结构矿山分段崩落法开采覆岩大规模破坏的数值模拟和理论研究

摘要: 陡倾结构金属矿山地下采动引起的地表移动范围往往远大于设计圈定的范围,严重威胁矿山安全生产、周边环境和人民生命财产安全。项目依托湖北程潮铁矿和金山店铁矿等陡倾结构金属矿山,建立陡倾结构金属矿山的地质结构概化模型,采用理论分析和数值模拟研究了分段崩落法采动效应下陡倾结构金属矿山覆岩变形破裂演化机制,并基于极限平衡理论,推导出了金属矿山围岩中的陡倾叠合悬臂梁在弯曲倾倒破坏或者剪切滑移破坏状态下侧面的法向力表达式。研究结果表明:1)陡倾结构金属矿山地表位移曲线表现出显著的阶梯状特征,岩层破坏表现为叠合特征;2)陡倾结构金属矿山往往在稍远离采空区的某个叠合岩层首先发生破坏,然后陡倾叠合岩层随着矿体的开挖不断地往上远离采空区和往下靠近采空区方向发生破坏,直到在深部形成一条贯通于采空区的大规模深部破裂面,破裂面往往与陡倾岩层层面法线方向夹角在12°–20°之间;3)陡倾结构金属矿山叠合岩层不断地向外发生破坏而使得岩层移动不断地向外传递的效应,使得陡倾结构金属矿山岩层移动范围过大,往往大于设计圈定的岩层移动范围;4)分段崩落法开采效应下陡倾结构金属矿山岩层破坏模式主要表现为弯曲倾倒破坏,靠近采空区的陡倾结构岩层则主要表现为剪切滑移破坏,其力学模型可以简化为陡倾叠合悬臂梁,通过不断地迭代计算,可以得到分段崩落法开采陡倾结构金属矿山岩层破坏的范围和稳定性判据。

 

Numerical and theoretical study of large-scale failure of strata overlying sublevel caving mines with steeply dipping discontinuities

Abstract: The deformation and fracture evolution mechanisms of the strata overlying mines mined using sublevel caving were studied via numerical simulations. Moreover, an expression for the normal force acting on the side face of a steeply dipping superimposed cantilever beam in the surrounding rock was deduced based on limit equilibrium theory. The results show the following: (1) surface displacement above metal mines with steeply dipping discontinuities shows significant step characteristics, and (2) the behavior of the strata as they fail exhibits superimposition characteristics. Generally, failure first occurs in certain superimposed strata slightly far from the goaf. Subsequently, with the constant downward excavation of the orebody, the superimposed strata become damaged both upwards away from and downwards toward the goaf. This process continues until the deep part of the steeply dipping superimposed strata forms a large-scale deep fracture plane that connects with the goaf. The deep fracture plane generally makes an angle of 12°–20° with the normal to the steeply dipping discontinuities. The effect of the constant outward transfer of strata movement due to the constant outward failure of the superimposed strata in the metal mines with steeply dipping discontinuities causes the scope of the strata movement in these mines to be larger than expected. The strata in the metal mines with steeply dipping discontinuities mainly show flexural toppling failure. However, the steeply dipping structural strata near the goaf mainly exhibit shear slipping failure, in which case the mechanical model used to describe them can be simplified by treating them as steeply dipping superimposed cantilever beams. By taking the steeply dipping superimposed cantilever beam that first experiences failure as the key stratum, the failure scope of the strata (and criteria for the stability of metal mines with steeply dipping discontinuities mined using sublevel caving) can be obtained via iterative computations from the key stratum, moving downward toward and upwards away from the goaf.

 

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