摘要
为解决窄煤柱沿空侧因支护失效导致的侧向约束弱化问题,提出了基于上区段端头垮落煤岩体注浆充填/加固的窄煤柱稳定性控制方法。通过施工穿透煤柱的钻孔,窥视了山东济宁鲍店煤矿6302综放工作面窄煤柱沿空侧煤岩体垮落堆积状态,直接摄像观测了工作面端头区煤岩体垮落堆积过程,分析了巷旁注浆加固的可行性。根据注浆加固前后煤柱的受力环境,建立了窄煤柱双面侧限(注浆前)及三面侧限(注浆后)的力学模型,并开展了窄煤柱承载力恢复实验,揭示了其承载力恢复机制。研究结果表明:①由于工作面端头不放煤或少放煤,窄煤柱沿空侧基本被上区段端头垮落的煤岩体及巷道坠落的破碎顶煤充填严实,以垮落煤岩体为骨料进行注浆充填具备可行性。②可以通过双面侧限转三面侧限的方式模拟巷旁注浆充填条件下的窄煤柱承载力恢复效果。在煤柱压缩过程中,注浆加固体与煤柱表面需要一定的着力时间才能紧密接触;紧密接触后,在充填体的侧向约束下,煤柱整体承载力稳步提高。③在双面侧限轴向压缩条件下,窄煤柱表现出“人”字形剪切破坏;注浆加固后,煤柱由原来对称的“人”字形剪切破坏转变为向自由面扩容的破坏形式,煤柱趋于稳定。④对垮落煤岩体注浆后,理想条件下可使煤柱残余承载能力提高30%左右。现场工程显示,侧向注浆加固后的窄煤柱整体比较完整,得到了有效的控制,虽然窄煤柱裂隙比较发育,但是由于巷旁充填体同时具备堵漏风的作用,在开采过程中并未发现采空区发火等现象。
In order to enhance the weakened lateral constraint of narrow coal pillar induced by support failing along the gob-entry side,a stability control method by grouting the caved rock and coal mass at the working-face end was proposed.Several boreholes were drilled throughout the coal pillar,and the caving forms of coal and rock mass at the end area of 6302 longwall top coal caving working face in Baodian coal mine were investigated by conducting borehole detecting tests.The collapse process was also observed.Based on these tests,the feasibility of grouting reinforcement method was analyzed.The double-sided confined(before grouting reinforcement)and three-sided confined(after grouting reinforcement)models of coal pillars were established.Based on these models,some experiments were conducted to reveal the recovery effect of the bearing capacity of coal pillar.The results show that(1)the narrow coal pillar along the gob side is basically filled by the caved coal and rock mass from the end of the former working face and the top coal above the roadway.Therefore,it is feasible to employ caved coal and rock mass as aggregate for grouting.(2)The recovery effect of the bearing capacity of coal pillar could be simulated by conducting double-sided confined and three-sided confined tests.During the compression tests,it takes some time for the filling body and pillar to contact each other.Then,the overall bearing capacity of coal pillar gradually increases under the lateral constraint of the fill body.(3)After grouting the caved rock mass,the coal pillar changes from the original man-shaped shear failure to the failure mode of expanding,which could enhance the stability of the pillar.(4)The residual bearing capacity of coal pillar can be increased by about 30%under ideal conditions.The in-situ test shows that the narrow coal pillar that strengthened by the lateral grouting method is relatively intact and the stability is well controlled.Although some fractures in the coal pillar were developed,the phenomenon of gob spontaneous combustion has not been found due to the backfill effect of the filling body.
作者
张洪伟
万志军
张源
滕腾
陈宇龙
魏泽捷
ZHANG Hongwei;WAN Zhijun;ZHANG Yuan;TENG Teng;CHEN Yulong;WEI Zejie(School of Energy and Mining Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;Key Laboratory of Deep Coal Resource Mining,Ministry of Education of China,China University of Mining&Technology,Xuzhou 221116,China;School of Mines,China University of Mining&Technology,Xuzhou 221116,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2021年第4期1211-1219,共9页
Journal of China Coal Society
基金
国家自然科学基金面上资助项目(51674242)。
关键词
窄煤柱
端头区
垮落特征
注浆加固
综放开采
narrow coal pillar
working face ends
caving features
grouting reinforcement
longwall top coal caving
