深部开采围岩稳定性与岩层控制关键理论和技术

Key theories and technonogies for surrounding rock stability and ground control in deep mining

首先,介绍了地应力对采矿工程荷载作用方式的特殊性,阐述了地应力控制采矿开挖过程和岩层稳定性的力学机理。地应力是采矿开挖前就存在于地层中的天然应力,采矿开挖出现自由空间并引起地应力向自由空间释放,形成“等效释放荷载”,它作用在开挖自由空间的边界上,而不是采矿外边界上。“等效释放荷载”带动周围岩体变形、位移和应力集中,导致围岩和岩层失稳、破坏。这与传统力学理论“外边界加载模式”有本质区别。若将地应力直接加在采矿外边界上,将得出“采矿外边界位移最大、开挖周边位移最小”等一系列错误结果。为此,必须根据采矿设计的开挖形态,将地应力转换成“等效释放荷载”进行计算和分析,才能得到正确的结果。同时,必须认识到地下采矿是多步开挖过程,也就是多次“等效释放荷载”加载过程。岩体是非线性材料,荷载的力学效应具有加载途径性。优化开采布局、开采顺序等可以优化“等效释放荷载”加载途径和力学效应,实现更好的岩层控制效应。最后,提出了地下采矿围岩稳定性与岩层控制的基本原理和方法,指出:支护的根本目的是保护、改善和提高岩体的强度,必须改变把围岩当成一种被动的荷载加以支撑的传统认识;充分发挥围岩自身强度达到采矿工程稳定,是岩石力学最基本的原理。在深部高地应力条件下,为了控制岩层变形和移动,维持采矿工程的稳定,上述原理的指导尤其重要。

The special unloading mode of in-situ stress due to mining is introduced,and the mechanism of in-situ stress controlling the process of mining excavation and the stability of rock strata is expounded.In-situ stress is the natural stress originally existing in rock mass.Mining excavation produces a free space in the rock strata and simultaneously causes the release of in-situ stress to the free space,leading to the formation of"equivalent releasing load".The"equivalent releasing load"is acting on the boundary of the free space,not the outside boundary of the mining area.It makes deformation,displacement and stress concentration in surrounding rock mass,which are the factors causing surrounding rock and strata unstable or failure.It is different from the"outside boundary loading mode"of the traditional mechanic theory.If the in-situ stress is directly acting on the outside boundary of the mining area,the mechanical analysis will generate a series of wrong results,such as that the displacement is largest at the outside boundary of the mining area,and the smallest at the boundary of the free space.It is necessary to calculate the"equivalent releasing load"according to the already designed excavation plan and in-situ stress state prior to using the"equivalent releasing load"to make the mechanical analysis.At the meantime,it should be pointed out that mining is a multi-step excavation process,i.e.a multi-step loading process of"equivalent releasing load".The rock mass is a nonlinear material,its the mechanical effect of loading is remarkably dependent on the loading path.Optimizing mining layout and excavation steps can optimize the loading path of"equivalent releasing load"and its mechanical effect,thus getting better strata control.At last,the basic principles and methods for surrounding rock stability and ground control in underground mining are provided.It is pointed out that the essential purpose of the support is preserving,improving and enhancing the strength of rock,the surrounding rock could not be regarded as a passive load to be supported.It is a basic principle of rock mechanics that fully using the strength of rock itself to realize the stability of rock engineering.In deep mining with high-stress conditions,in order to make the stability of mining engineering by controlling rock deformation and displacement,the guidance of the above principle is especially important.