两淮煤系地层主要岩石单轴受压条件下的导电特性试验研究

设计一种岩石受荷条件下的岩石电阻率试验装置。通过试验,发现一种取材方便、效果良好的电极耦合材料——过饱和黏土。试验研究两淮煤系地层主要岩石的导电性随电流、电压、应力的变化特性,并拟合出各岩样较高相关度的电阻率-应力(ρ-σ)回归方程,结果发现:(1)两淮煤田煤系地层岩石在弹性变形范围内,其导电性随着应力的增大而增强(即岩石的电阻率随着应力的增大而降低);(2)软弱砂质泥岩导电性受应力影响的程度大于坚硬的砂岩、闪长岩;(3)岩石电阻率与应力之间存在较好的相关性;(4)在应力一定的条件下,软弱砂质泥岩的导电性随着电压、电流的增强而增强(电阻率降低),坚硬砂岩、闪长岩的导电性基本不受电压、电流的影响。在两淮煤田深井巷道围岩松动圈的高密度电阻率法探测中,将测试得到的巷道围岩视电阻率断面图或电阻率反演断面图与岩石电阻率试验获得的ρ-σ回归方程相结合,分析巷道围岩松动圈的发育状况,取得较好的工程效果。

EXPERIMENTAL STUDY OF ELECTRICAL CONDUCTIVITY OF MAIN ROCKS IN STRATA OF HUAIBEI AND HUAINAN COALFIELD UNDER UNIAXIAL COMPRESSION

The test equipment of litho-electric experiment under loading was designed. Through experiments a convenient and effective coupling electrode material，the over-saturated clay，was found. The changing rule of the electrical conductivity of main rock specimens in the coal-bearing strata in Huaibei and Huainan Coalfield(HHC) in relation to changes of current，voltage and stress was also studied experimentally. And resistivity-stress regression equations of different rock masses were fitted with much high correlation coefficient. Research results show that：(1) within the range of elastic deformation，the electrical conductivity of the coal-bearing rocks in HHC increases with the enhancive stress，i.e. the rock resistivity decreases with increasing stress；(2) the electrical conductivity of the weak sandy mudstone is more susceptible to the variation of stress than the hard sandstone and diorite；(3) there exists a good correlation between the resistivity of the rock and stress；(4) under certain conditions of stress，the electrical conductivity of the weak sandy mudstone will be enhanced with the increase of the voltage and the current，thereby the resistivity is reduced，while the electrical conductivities of the hard sandstone and diorite are to some extent unaffected by voltage and current. In measuring and testing released zone of surrounding rock of roadway by high density resistivity method in mines in HHC，measured apparent resistivity section or resistivity inversion section is combined with the resistivity-stress regression equations obtained from litho-electric experiment to analyze the development of released zone of surrounding rock of roadway. The technology has been successfully applied to engineering practice.