矿井多匝小回线瞬变电磁法理论基础研究

Transient electromagnetic method was widely used in underground coal mine, however the issues of its apparent resistivity calculating, anomaly spatial location, target body orientation detection and time-depth transformation have not been well solved. To be restricted by the working space, multi-turn small coil is the only device adopted by mine transient electromagnetic method, which makes instrument measurments of apparent resistivity much less than the intrinsic resistivity of coal rocks. Multiplying with a factor subjectively has been a common method to correct measured data, which influences the further processing and interpretation of mine transient electromagnetic data directly. The law of transient electromagnetic field around the roadway caused by the multi-turn small coil in whole-space will be revealed, in order to set up a new method for computing the whole-space and full-period apparent resistivity of multi-turn small coil transient electromagnetic method, which could express the real electrical characteristics of coal rocks objectively. With numerical simulation and physical model experiments, the whole-space transient electromagnetic response characteristics of geological bodies in different directions will be analyzed. A method to recognize measured geoelectric anomaly spatial orientation will be raised, and the directional observation system of specific location target bodies will be developed. Using conductive sphere and thin layer as examples, the effective detection range will be evaluated respectively when the multi-turn small coil array is applied in the roof or floor transient electromagnetic sounding and the advanced detection heading of a driving face . Afterwards, the time-depth transformation formula for multi-turn small coil transient electromagnetic method will be established. This research will provide theoretical basis for underground working, data processing and interpretation of multi-turn small coil transient electromagnetic method.

瞬变电磁法在煤矿井下广泛应用，但视电阻率计算、异常空间定位和目标体定向探测以及时间—深度转换问题一直没有很好地解决。受施工空间的限制，矿井瞬变电磁法只能采用多匝小回线装置，造成仪器视电阻率读数远小于煤岩本征电阻率。人们普遍采取乘数的方式主观调整实测数据，直接影响矿井瞬变电磁资料的进一步处理与解释。本项目将揭示巷道影响下多匝小回线瞬变电磁场全空间分布变化规律，建立多匝小回线瞬变电磁法全空间全期视电阻率计算方法，以客观真实地表达煤岩电性特征；通过数值模拟和物理模型实验，阐明不同方位地质体的全空间瞬变电磁响应特征，提出实测地电异常空间方位的辨识方法，开发特定方位目标体的定向观测系统；以良导球体和导电薄层为例，分别评估多匝小回线装置应用于顶、底板瞬变电磁测深和掘进头超前探测时的有效探测距离，并建立多匝小回线装置瞬变电磁时间—深度转换公式，为煤矿井下瞬变电磁法施工、资料处理与解释奠定理论基础。

（1）提出了多匝小回线装置瞬变电磁视电阻率新的计算方法和时—深转换方法。从理论上推导了不同阻尼状态下的瞬变电磁暂态响应方程，并采用Simulink软件进行模拟仿真，查明了多匝小回线装置晚期视电阻率公式计算结果低于岩石西征电阻率几个数量级的原因，从本质上认识了装置对观测结果的滞后效应，基于线性时不变系统传输特性的新公式符合客观实际，为多匝小回线瞬变电磁测深装置的推广应用提供了科学依据；.（2）全面总结了煤矿防治水典型地电异常体的矿井瞬变电磁响应特征，研究了多匝小回线发射装置的延时特性，获得了小尺寸发射装置的关断时间特征，提出了关断影响的校正方法；..（3）采用模型实验方法进行了地电异常体空间定位和定向探测机理研究，建立了多匝小回线装置瞬变电磁模拟实验的相似准则；合理设计了物理模型装置和实验方案，优化筛选了适用于井下不同方位地电异常体探测的装置形式；.（4）科学评价了多匝小回线瞬变电磁法的探测能力，在统一框架下建立了全、半空间层状介质正演模拟算法，研究了三层全空间地电模型瞬变电磁响应特征与装置形式及地层参数间的关系，系统分析了矿井瞬变电磁法的薄层分辨能力、横向分辨率、纵向分辨率、最小探测深度以及最大探测深度的主要影响因素；.（5）基于B/S结构，开发了集矿井瞬变电磁工程ERP、实测资料预处理与可视化、实测资料处理与解释、地质报告订制、内业外业质量监控于一体的在线协同处理与解释软件系统；.（6）以含煤地层突水、冲击矿压等动力灾害的电各向异性特征研究为目标，充分利用巷道施工条件，提出了张量电阻率法观测新技术，初步探讨了张量电阻率法在超前探测特别是定点监测方面的应用优势，为及时发现煤矿动力灾害地电先兆信息提供了有效方法技术途径。. 项目组在晋能控股煤业公司连续四年跟踪进行井下电法技术试验工作，在国内外重要期刊发表高水平学术论文19篇，申请国家发明或实用新型专利4件，培养博士、硕士毕业研究生11人和博士后1人。