直流电阻率法在煤层底板水害监测中的应用研究

Research on the application of direct current resistivity method in coal seam floor water inrush monitoring

目前针对直流电阻率法在煤层底板水害监测中应用的研究成果主要集中于底板变形与破坏的电阻率响应特征上,对导水通道动态发育过程的电阻率变化规律研究较少。针对华北型煤田面临的底板承压水害问题,采用直流电阻率法对采动影响下的底板含、导水异常构造进行监测。首先,介绍了采煤工作面直流电阻率监测系统工作原理和基于电阻率三维反演的监测数据自动处理解释方法;然后,构建了底板突水过程监测地质模型,对底板含、导水构造发育过程进行数值模拟研究;最后,在煤矿井下开展了底板直流电阻率监测试验。数值模拟结果表明:根据电阻率三维反演结果可识别含、导水异常构造在测线走向上的展布范围;根据电阻率随时间的变化趋势可推断异常构造的发育情况,随着含、导水异常构造向上发育,低阻异常响应逐渐增强,低阻异常在垂向的展布范围逐渐增大。井下试验结果表明:利用直流电阻率监测成功捕捉了采煤工作面底板出水过程,电阻率出现异常变化的时间早于工作面实际出水时间;工作面涌水量增加之前,低阻响应表现出逐渐增强的变化趋势,与数值模拟结果基本一致;工作面出水后,低阻异常逐渐减弱。研究结果表明可利用直流电阻率法进行工作面水害预警,但要准确判断异常构造的发育高度还需结合其他监测手段进行综合解释。

The current researches on the application of direct current resistivity method in coal seam floor water inrush monitoring mainly focus on the resistivity response characteristics of the deformation and damage of the floor,and there are few researches on the resistivity change law of the dynamic development process of water channels.In order to solve the problem of floor water inrush in the North China coalfield,the direct current resistivity method is used to monitor the abnormal structure of floor water-bearing and water-conducting under the influence of mining.Firstly,the paper introduces the working principle of direct current resistivity monitoring system at coal working face and the automatic processing and interpretation method of monitoring data based on three-dimensional inversion of resistivity.Secondly,the paper constructs a geological model for monitoring the process of floor water inrush and carries out the numerical simulation study of the development process of floor water-bearing and water-conducting structures.Finally,the floor direct current resistivity monitoring test is carried out in the coal mine.The numerical simulation results show that the distribution range of abnormal structures of water bearing and water conducting along the survey line can be identified based on the resistivity three-dimensional inversion results.The development of abnormal structures can be inferred from the changing trend of resistivity over time.The low-resistance anomaly response gradually increases as the abnormal water bearing and water conducting structures developing upward,and the low-resistance anomaly increases gradually in the vertical direction.The results of the coal test show that the direct current resistivity monitoring successfully captures the process of water inrush from the floor of coal working face,and the time of abnormal changes in resistivity is earlier than the actual water inrush time of the working face.The low resistance response gradually increases before the increase of water inrush from the working face,which is basically consistent with the numerical simulation results.After the water inrush from the working face,the low resistance abnormality gradually weakens.The results show that the direct current resistivity method can be used for early warning of water inrush from the working face.However,determining the development height of the abnormal structure accurately requires a comprehensive interpretation combined with other monitoring methods.