采动影响下煤层覆岩电性变化规律研究
Study on electrical property variation law of overburden strata above seam under mining influences
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摘要: 为正确确定煤层覆岩受采动变形与破坏范围,更好地了解煤层采动影响下覆岩视电阻率的变化及破坏发育特征,结合围岩的力学性质、岩性与采煤方法等因素进行综合分析,将覆岩分成塑性破坏区、弹塑性过渡区、弹性区3个不同的导电性区段,分别建立了煤层受采动影响下覆岩电性动态变化的正常与存在导水裂隙带的地电模型,并对模型进行正演模拟研究。结果表明:覆岩受采动引起其视电阻率显著变化,视电阻率异常区随回采工作面的推进而移动,且其范围随之加大,致使导水裂隙能与塑性破坏高阻区相连,反映在塑性破坏高阻异常范围和幅度的减小,预示着顶板可能出水;利用覆岩受采动电性变化规律,有利于更为准确的探测顶板水的赋存状态可保障工作面的安全开采。Abstract: In order to accurately determine the mining deformation and failure scope of the overburden strata above seam and better understand the apparent resistivity variation and failure development features of the overburden strata under the influences of the seam mining,in combination with the mechanics properties of the surrounding rock,lithology,mining method and other factors,a comprehensive analysis was conducted. The overburden strat a were divided into three different electric conductivity sections ,including a plastic failure section,e lastic-plastic transition section and elastic section. T he geoelectric models of the overburden strata with normal electric property dynamic variation and existed water flow crack zone under the influences 0 f the seam mining were established individually and a forward simulation study was conducted on the model. The results showed that affected by the mi ning,the apparent resistivity of the overburden strata was varied obviously and the apparent resistivity abnormal zone would be displaced with the forwa rd advancing of the coal mining face. The scope of the abnormal zone would be increased with the coal mining face forward advanced. Thus the water f low cracks would be connected with the plastic failure and high resistance zone. When the plastic failure high resistance abnormal scope and range red uced,a water inrush from the roof could be predicted. Affected by the mining,the application of the overburden strata electric property variation law coul d be favorable to accurately detect the roof water deposition status in order to protect the safety mining of the coal mining face.