矿井并行电法技术体系与新进展

Applied technologies and new advances of parallel electrical method in mining geophysics

  • 摘要: 并行电法(Parallel Electrical Method,PEM)是集阵列式、全电极、全波形3种电场(自然电场、激励电场和感应电场)的同步采集和处理于一体的地电场勘探方法,它以时空域地电场的并行测试与并行处理为核心思想:通过每个电极1个ADC及开关装置的集成,实现全部电极的并行激励与采集,获得包括AM法和ABM法两种形式的地电场数据体;按照电极的空间组合与时序关系,解编出激励电流序列和对应的自然电场(零次场)、激励电场(一次场)和感应电场(二次场)的电位响应序列,再根据电位响应与电流激励的传递原理解析出探测介质的电阻抗属性(包括自然电位、电阻率和极化率等参数),由此实现3种电场信息的并行解析。矿井并行电法(Mine-PEM)充分利用了巷道空间、钻孔空间及其组合形式,进而实现了对煤层顶底板充水水源、导(含)水断层、岩溶陷落柱及注浆改造效果的有效探查,对采动围岩破坏特征及富水异常区的动态检测,以及对地下水渗流演化的实时远程监测及水害超前预警等,这些技术于过去15 a间在全国煤矿防治水领域得到推广应用,发展、形成了矿井并行电法技术体系。矿井物联网技术的普及,使网络并行电法的智能特色得以发挥,实现了矿井地电场定时激励采集与实时动态监测的在线远程控制;双模式电极测试技术(Double-mode Electrode Testing Technique)的引入与应用,解决了常规地电场测试技术(如高密度电法)中激发、接收共用同一电极而导致自然电场、感应电场数据误差大甚或失效的问题,保证了3种电场并行测试数据的有效性;由此,并行电法技术实现了对主动源电法勘探与被动源地电场监测的有效融合,这对矿井灾害源动态、精细探测尤其是水害预警来说意义重大,形成的并行电法国家能源行业标准已得到实施。并行电法不仅可为智能矿山、透明矿山的建设提供技术保障,而且在工程与环境物探领域以及城市地下空间精细探查中也已得到推广。当前,地电场多参数的并行解析与联合反演是其重点研究内容,通过对介质电阻抗成像理论的深入研究,有望为岩土体多相介质多场耦合作用及其演化特征的探查提供有效手段。

     

    Abstract: Parallel Electrical Method ( PEM) is a kind of geoelectric field exploration method,which integrates the synchronous acquisition and processing of whole array,all electrodes,all waveforms and three kinds of electric fields. It takes the parallel measurement and parallel processing of geoelectric field in both space and time domain as its core idea based on the integration of an ADC and a switch device for each electrode,the parallel excitation and acquisition of all electrodes are realized,and the geoelectric data volume is obtained containing AM mode and ABM mode. Ac- cording to the space combination and time series of electrodes,the excitation current sequence and potential response sequence of natural electric field ( zero field),excitation electric field ( primary field) and induction electric field (secondary field) are decomposed,and thus the resistance properties (including self-potential,resistivity and polariz- ability etc. ) of the detecting medium are analyzed according to the transmission principle of potential response and current excitation,therefore,the parallel analysis of three kinds of electric field information is realized using this meth- od. The Mine-PEM makes full use of roadway space,borehole space and its combination form in coal mine,thus it can effectively explore water-filled source,water-bearing fault,karst collapse column and grouting effect in both roof and floor,dynamically detect mining rock damage characteristics and water-rich anomaly area,real-timely monitor groundw- ater seepage evolution and predict mine water disasters. In the past 15 years,these techniques have been widely ap- plied and promoted in coal mine water disaster prevention all over China,as a result of which the technology system of Mine-PEM has been established. The intelligent characteristics of Network Parallel Electrical Method show its advanta- ges thanks to the popularization of Internet of Things technology in coal mines in China,which realizes the online re- mote control of timing excitation and acquisition as well as real-time dynamic monitoring of mine geoelectric field. Fur- thermore,the Double-mode Electrode Testing Technique overcomes the shortcomings of using the same electrode for both excitation and acquisition in normal geoelectric measuring techniques,such as multi-electrode resistivity method (high-density electrical method),which always results in errors or even failures with natural electric field and induced electric field data,and this technique ensures the data validity of PEM. Therefore,the PEM effectively integrates active source exploration and passive source monitoring,which makes a significant contribution to the dynamic and fine de- tection of mine disaster sources,especially to mine water hazards early-warning,and presently two Chinese energy in- dustry standards closely related to PEM has been implemented. Additionally,PEM not only provides a technical sup- port for intelligent mines and transparent mines construction in China,but also has been widely used in engineering ge- ophysics,environmental geophysics and urban underground space exploration areas. At present,the parallel analysis and joint inversion of multi-parameters of geoelectric field is the key research area of PEM,and by studying the elec- tric impedance tomography theory based on PEM,effective means should be formed to explore multi-field coupling and evolution characteristics in multi-phase media.

     

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