基于时移高密度电法的覆岩精细探测方法研究

Fine detection of overburden strata based on time lapse high density resistivity method

地下煤层开采引起上覆岩层变形破坏,对变形破坏范围进行精细探测,可以为煤矿安全高效绿色开采提供技术保障。本论文分析了基于时移高密度电法的覆岩精细探测原理,建立了采前和采后三维地质地球物理模型并进行了数值仿真计算。结果表明:覆岩变形破坏在电阻率变化率断面图中呈沙漏形异常,孔口位置约为裂隙带和弯曲下沉带的分界线,裂隙区相对压实区为电阻率变化率高正异常区。同时,进行了现场试验,发现电阻率变化率断面图中浅部异常主要受沉陷裂隙和降水影响,沉陷裂隙形成电阻率变化率正异常,降水形成电阻率变化率负异常;结合沙漏形异常形态和关键层层位,确定了裂隙带发育高度为98 m,探测结果得到了钻探结果验证。

Fine detection for the deformation failure of overburden strata caused by underground mining may provide reliable guidance for safety,high efficient and green coal mining.Firstly,the principle of overburden detection based on time lapse high density resistivity method was investigated.Then 3D geologic-geophysical models of overburden strata before and after mining were constructed,and the corresponding numerical simulation was carried out by using these models.It is demonstrated that deformation failure of overburden strata is hourglass-like in the resistivity change rate profile and orifice is the separatrix between the fractured zone and the bending zone.Furthermore,field tests were carried out,results show that the surface subsidence caused positive anomaly and precipitation caused negative anomaly in the resistivity change rate profile.Based on the hourglass-like anomaly morphology and key stratum layer,the height of fractured zone was determined to be 98 m.Finally,the results from time lapse detection were verified by drilling results.