摘要
针对传统矿压理论中对采场承载体系的解析所存在的问题,本文提出采用球应力这一表征岩体三维应力及完整性状态的力学参量进行工作面围岩稳定性控制分析。基于充填采场上覆岩层结构及球应力分布的相互关系研究,认为采场围岩中存在对其稳定性起主控作用的球应力壳结构。采用FLAC3D数值软件建立了充填开采的全应变软化数值模型,模拟分析了充填开采采场球应力壳的空间分布形态及其随工作面推进的演化规律。研究表明:球应力壳由低球应力值的应力核区及核外区域所组成,球应力壳随工作面推进呈现阶段性时空演化特征,其趋稳过程历经上壳发展、上壳稳定、下壳发展及应力壳稳定4个阶段;工作面推进距离小于工作面长度时,球应力壳受开采进度影响明显,并且相对上壳而言下壳的发展具有明显的滞后性;顶底板塑性区的破坏范围与球应力核区域范围相同且随工作面的推进保持同步协调关系,扩展空间由下及上,破坏深度由表及里,破坏形式由拉及剪。
Aiming at the problems existing in the analysis of stope bearing system in traditional rock pressure theory, this paper proposes the use of spherical stress, a mechanical parameter representing the three-dimensional stress and integrity state of rock mass, to analyze the stability of surrounding rock in working face. Based on the analysis of the interaction relationship between the overlying strata structure and the spherical stress distribution in the stope, spherical stress shell structure which exists in the surrounding rock of the stope is put forward and it plays a main role in the stability of stope. The whole strain softening numerical model of backfilling mining is established by using FLAC3 D numerical software. The spatial distribution pattern and the evolution law of the spherical stress shell with the advancing of backfilling mining working face are simulated and analyzed. Research shows that the spherical stress shell is composed of nuclear area with low spherical stress and region outside the nuclear area. Processes of spherical stress shell evolution with working face advancing are characterized by four different stages: upper shell development, upper shell stability, lower shell development, stress shell stability; spherical stress shell is significantly influenced by mining progress when the advancing distance is less than the length of the working face, and the lower shell is obviously lagging behind in terms of upper shell development; the plastic region is the same with the range of spherical stress nuclear area and keeps coordination with the working face advancing. The plastic region expands from down and up, damage depth is from the outside to the inside and the form of destruction is made by pulling and shearing.
引文
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