采场全生命周期及其应力的时空演化特征分析

Dynamic evolution characteristic on stope pressure in whole life cycle of stope

井工开采过程中采场应力的分布及演化规律对于回采巷道及工作面围岩的稳定性控制至关重要。本文将开切眼到停采的全部过程称之为采场全生命周期,且将采场应力分为工作面超前支承应力和工作面顶板应力两部分,基于材料力学建立了采场全生命周期内覆岩结构模型得到了不同阶段超前支承应力的力学函数;借助UDEC软件来分析采动过程中覆岩结构的时空演化过程和超前支承应力的动态演化特征,得到了工作面超前支承应力和工作面顶板应力的协调非同步演化特征,认为单个周期来压内超前支承应力峰值会在空间和时间上超前于工作面顶板应力峰值出现,且二者均表现出周期来压前大于来压后的规律,在采场全生命周期内在采动达到非充分采动和充分采动交界点阶段先后达到极值,因此依据采场应力的演变规律将采场全生命周期分为发生期(Ⅰ)、发育期(Ⅱ)、稳定期(Ⅲ)3个阶段:发生期(Ⅰ)对应的是开切眼至基本顶初次来压,采场应力保持稳定的缓慢增长;发育期(Ⅱ)对应的是周期来压至非充分采动与充分采动阶段的交界点,采场应力保持不同的增长速率;稳定期(Ⅲ)对应的是充分采动直到停采阶段,采场应力保持着较为稳定的波动;通过对采场全生命周期及其应力的演化特征分析及划区可以预先对回采过程中的高位应力区进行判定,及早采取相应的措施,为采场的安全提供保障。

The distribution and evolution characteristic of the stope pressure is a key factor to controlling sur-rounding rock in underground coal mining.The whole life cycle of stope is referred to the entire process from first cut to the termination of mining operation in this paper.The stope pressure consists of two parts including the advanced abutment pressure and mining face roof pressure.Aiming to analyze the dynamic evolution characteristic of the stope roof pressure,UDEC simulation analysis and different surrounding rock mechanical models of over-lying strata at corresponding multi-time-space conditions were applied.It is demonstrated in this study that the maximum advanced abutment pressure occurs earlier under time dimension and spatial dimension,as compared with the mining face roof pressure during a single periodic weighting process.When the mining face has advanced to the critical extraction point,the advanced abutment pressure and mining face roof pressure reach their extreme value successively.Thus,the whole life cycle of stope can be divided into three stages,which are initial stage(Ⅰ),growing stage(Ⅱ)and stable stage(Ⅲ).The initial stage(Ⅰ)corresponds to the period from first cut to first weighting,in which the stope stress increases softly.The growing stage(Ⅱ)is from the periodic weighting to the critical extraction point between non-fully mining disturbance and fully mining disturbance.From critical extraction to the finish line is defined as stable stage(Ⅲ).During stageⅡ,the stope stress increases faster than that in stageⅠ,and during the last stageⅢ,the stope stress changes stably.According to the dynamic evolution of stope pressure featured in life cycle of stope,it could be used to predict the high stressed zone,and the reinforcement support or pressure-relief methods could be applied and adjusted in advance,which can provide a safer mining environment.