厚黏土层软弱覆岩采动破坏的泥盖效应  

Mud cover effect of mining-induced failure of soft overburden in thick clay strata

作　　者：樊振丽 刘治国[3,4] FAN Zhenli;LIU Zhiguo(CCTEG Coal Mining Research Institute,Beijing 100013,China;Coal Mining and Designing Department,Tiandi Science&Technology Co Ltd,Beijing 100013,China;Beijing Tiandi Huatai Mining Management Co Ltd,Beijing 100033,China;Coal Mining and Designing Branch,China Coal Research Institute,Beijing 100013,China)

机构地区：[1]中煤科工开采研究院有限公司,北京100013 [2]天地科技股份有限公司开采设计事业部,北京100013 [3]北京天地华泰矿业管理股份有限公司,北京100013 [4]煤炭科学研究总院开采研究分院,北京100013

出　　处：《采矿与安全工程学报》2020年第6期1196-1204,共9页Journal of Mining & Safety Engineering

基　　金：国家自然科学基金青年科学基金项目(51704161);天地科技股份有限公司科技创新创业资金专项项目(2019-TD-MS004)。

摘　　要：以榆神矿区某矿2301工作面为例,采用钻孔注水、孔内视频采集和相似材料模拟试验3种研究方法,对厚泥盖层下覆岩破坏规律进行了综合研究。通过井下钻孔冲洗液漏失量和孔壁裂隙发育特征的观测,确定了垮落带、导水裂缝带的发育高度,相似材料模拟试验揭示了采动裂隙“发生-发展-弥合”的动态演化特征,指出厚泥盖层下采动破坏显现出“泥盖效应”。同时,运用XRD、SEM和膨胀性测试等实验方法,分析了泥盖效应产生的矿物学原因。研究表明:薄基岩厚泥盖条件下,采高为7 m时,覆岩破坏高度为45.7~49.3 m,裂采比6.53~7.04,较类似开采条件中硬类型覆岩破坏高度降低了15%~53%;基岩厚度变化时,覆岩破坏形态呈现非对称特点,沿工作面推进方向呈现弥合分区特征,泥盖层在裂隙演变过程中易出现整体下沉,且对采动裂隙的上向发育起主导作用;黏土矿物具有的强塑性、亲水性、膨胀性等是泥盖效应产生的本质原因,当导水裂缝带上部的微小裂隙进入到黏土层,由于黏土矿物良好的膨胀性,使裂隙会在采动影响的发生和发展过程中自行闭合,同时泥盖层受载后亦易于密实,从而抑制导水裂缝带的发育,显现出“泥盖效应”相关特征。With working face 2301 of a coalmine in Yushen mining area as an example,the failure law of overburden rock under thick mud cover was studied comprehensively through borehole water injection,borehole video acquisition,and similar material simulation test.The heights of caving zone and water-conducting fractured zone were determined through observation of borehole flushing fluid leakage and development characteristics of hole wall fissure.The simulation test of similar materials has revealed the dynamic evolution characteristics of mining-induced fissure“occurrence-developmentbridging”,indicating that the mining-induced failure under thick mud cover shows the“mud cover effect”.At the same time,the mineralogical causes of mud cap effect have been analyzed through XRD,SEM and expansibility test. The study has shown that under the condition of thin bedrock and thick mud cover, when the mining height is 7m, the overburden failure height is 45.7~49.3m, and the fracture recovery ratio is 6.53~7.04, which is 15%~53% lower than that of hard overlying rock under similar mining conditions. When the thickness of bedrock changes, the failure morphology of overburden rock presents asymmetric characteristics, and it shows the characteristics of bridging zones along the advancing direction of working face. Mud cap is prone to overall subsidence in the process of fracture evolution, and plays a leading role in the upward development of mining-induced fractures. Clay minerals have strong plasticity, hydrophilic, dilatability, which is the essence of mud cover effect. When the tiny cracks in the upper part of the water-flowing fractured zone get into the clay layer, the crack will be self-closed in the process of mining influence due to good expansibility of clay minerals;at the same time, mud cap is easily compacted by gravity, thus inhibiting the growth of water flowing fractured zone, and showing “mud cover effect” related features.

关 键 词：导水裂缝带 覆岩破坏 黏土矿物 泥盖效应 保水开采 

分 类 号：TD325[矿业工程—矿井建设]