新街矿区厚硬顶板条件邻空巷道冲击地压机理与控制

Mechanisms and control of rock bursts in goaf-side roadways under the condition of thick and hard roofs in the Xinjie mining area,Inner Mongolia

【目的和方法】针对厚硬顶板条件下深部矿井回采巷道冲击地压严重威胁工作面安全生产的问题,以内蒙古新街矿区典型深采矿井3-1103工作面辅运巷为工程研究背景,分析邻空巷道冲击地压频发区域外在主控因素和内在驱动力源;构建基于软化地基与弹性地基假定“岩梁-地基”系统力学特性的顶板断裂前受载力学模型,解析采场覆岩结构演化过程厚硬顶板岩梁能量演化规律及其主控因素;运用FLAC3D模拟并探查邻空巷道冲击失稳高风险区域位置与特征;研究采场覆岩结构优化与围岩应力能量控制方案,制定厚硬顶板破断诱发邻空巷道冲击地压控制方法。【结果和结论】结果表明:(1)邻空巷道冲击地压频发区域易发生以高静载或高静载叠加动载为主导灾变力源的失稳破坏,影响因素主要为顶板厚硬岩层、邻近采空区、区段煤柱。(2)顶板储能总量与覆岩载荷、软化地基系数、顶板岩梁弹性模量及惯性矩、采空区顶板极限跨距、工作面支架参数等有关。其中,覆岩载荷、软化地基系数和采空区顶板极限跨距与岩梁应变能密度呈正相关,顶板岩梁弹性模量及惯性矩、工作面支护参数与岩梁应变能密度呈负相关。(3)回采期间3-1103工作面超前支承压力区及其影响区域内区段煤柱和回采巷道煤体呈现多因素叠加影响,发生应力集中和能量积聚,是冲击失稳高风险区域;该区域较3-1101综采面其围岩应力与能量集中度进一步加剧增大。其中,工作面前方应力和应变能密度峰值增幅最大分别为6.61%、12.04%,区段煤柱应力和应变能密度峰值增幅最大分别为29.06%、65.14%。(4)提出了“卸压爆破预处理高静载区域+深孔爆破或水力致裂预裂厚硬顶板+强化巷道吸能防冲支护”的解决方案,现场应用效果明显。

[Objective and Methods]Rock bursts in mining roadways in deep coal mines under the condition of thick and hard roofs severely threaten the safe coal mining of the mining face.To meet this threat,this study,focusing on the No.3-1103 mining face auxiliary transport roadway,a goaf-side roadway,in a typical deep mine of the Xinjie mining area,Inner Mongolia,analyzed the external dominant factors and internal driving sources for frequent rock bursts in the goaf-side roadway.Assuming the mechanical characteristics of the rock beam-foundation system,this study constructed mechanical models under loading before roof fracturing based on soft and elastic foundations.Using these models,this study determined the evolutionary patterns of the rock beam energy in the thick and hard roof during the structural evol-ution of overburden in the stope,as well as their dominant factors.Based on FLAC3D simulation results,this study in-vestigated the locations and characteristics of high-risk zones of rock burst-induced instability in the goaf-side roadway.Finally,this study developed a scheme for optimizing overburden structures and controlling the stress energy of sur-rounding rocks in the stope,along with a method for controlling rock bursts in the goaf-side roadway induced by the fracturing of the thick and hard roof.[Results and Conclusions]The results indicate that zones with frequent rock bursts in the goaf-side roadway are susceptible to instability failures caused primarily by high static loads or high static loads with superimposed dynamic loads.The primary influencing factors of such failures include the thick and hard roof,the adjacent goaf,and section coal pillars.The total energy storage capacity of the roof is related to factors like overburden load,soft foundation coefficient,the elastic modulus and moment of inertia of rock beams in the roof,the limit span of the goaf roof,and the support parameters of the mining face.Specifically,the strain energy density of the rock beams is positively correlated with the overburden load,soft foundation coefficient,and limit span of the goaf roof but negatively correlated with the elastic modulus and moment of inertia of rock beams in the roof and the support parameters of the mining face.During the coal mining along the No.3-1103 mining face,section coal pillars and coals in the mining road-way within the advance support pressure zone and its influencing zones are affected by superimposed multiple factors,which lead to stress concentration and energy accumulation.Therefore,these zones face high risks of rock burst-induced instability.Compared to the No.3-1101 fully mechanized mining face,these zones exhibit significantly intensified sur-rounding rock stress and energy concentration.The peak values of stress and strain energy densities in front of the min-ing face increase by 6.61%and 12.04%at most,respectively.In contrast,the peak values of stress and strain energy densities of section coal pillars increase by 29.09%and 65.14%at most,respectively.Finally,this study developed a comprehensive scheme involving the blasting and pressure relief of high static load zones,the pre-fracturing of the thick and hard roof through deep-hole blasting or hydraulic fracturing,reinforcing energy-absorbing and anti-rock burst sup-ports in the roadway,with significant effects having been achieved in the field application of this scheme.