深井直覆硬厚顶板侧向破断模式及采动应力响应特征研究

Lateral fracture mode and mining stress response characteristics of overlying and thick-hard roof in deep mining well

针对深井“三巷布置”工作面临空巷强烈矿压显现现象,以煤层直覆硬厚顶板为工程背景,运用理论分析、相似模拟、现场实测等研究手段,分析直覆硬厚顶板侧向破断模式,揭示临空巷强矿压显现机制,明晰工作面采动应力响应特征。研究结果表明:直覆硬厚顶板破断后,在工作面侧向形成长悬臂-铰接结构,破断线位于采空区内。直覆硬厚顶板岩性特征和几何特征决定着临空巷矿压显现程度,顶板越硬或者越厚,采空区煤体周围越容易产生较高的应力集中。直覆硬厚顶板下巷道围岩应力集中程度高,且临空侧超前支承压力影响范围更广,应力集中程度更高,巷道矿压显现更为剧烈;煤柱上侧向支承压力呈“同步受力、同步增长”变化特征,进入采空区稳定阶段后支承压力表现L+W型应力特征,相邻待采工作面煤柱侧出现非对称的应力峰值,煤柱中部出现应力双峰。受侧向高应力影响,下一区段巷道围岩主要表现为两帮中下部剧烈变形。基于工作面直覆硬厚顶板侧向破断特征和强动载矿压显现机制,提出了顶板灾害超前治理、“浅部强力支护+深部多层次卸压”的防控技术体系,为采场岩层控制提供有益指导。

Targeting the phenomenon of strong mining pressure in empty tunnels at the“three lane layout”face in deep well,the lateral fracture mode of overlying and thick-hard roof was analyzed by the methods such as theoretical analysis,similarity simulation,and on-site measurement.This analysis reveals the mechanism of strong mining pressure in empty tunnels and clarifies the characteristics of mining stress response of the working face,taking the coal seam directly overlying the hard and thick roof as the engineering background.The results indicate the formation of a lateral long cantilever-hinge structure within the working face,with the fracture line situated within the goaf subsequent to the fracturing of the overlying thick-hard roof.The rock properties and geometric configurations of the overlying and thick-hard roof layers significantly influence the magnitude of mining-induced stress in the goaf.The greater the hardness and thickness of the roof,the higher the likelihood of stress concentration occurring around the coal body within the goaf.Not only the stress concentration in the surrounding rock of the roadway is high,but also the influence range of the advance support pressure on the goaf side is wider,the degree of stress concentration is higher,and the mining pressure in the roadway is more severe,under the condition of overlying and thick-hard roof.The abutment pressure on the coal pillar exhibits a characteristic of“synchronous force and synchronous growth”.Upon reaching the stabilization phase of the goaf,the abutment pressure manifests as an L+W stress profile,featuring asymmetric stress peaks on the adjacent upcoming mining coal pillars and double stress peaks in the center of the pillars.Under the influence of high lateral stress,the middle and lower portions of the surrounding rock in the subsequent roadway section undergo significant deformation,whereas the roof remains unaffected.Based on the lateral fracture characteristics of the overlying and thick-hard roof and the mechanism of strong dynamic mining pressure manifestation,a prevention and control technology system for roof disasters is proposed,which includes advanced treatment of roof disasters and“shallow strong support+deep multi-level unloading”.This provides beneficial guidance for rock strata control in mining stope.