矿井瞬变电磁传统视电阻率算法的可靠性分析

Reliability Analysis of the Conventional Apparent Resistivity Arithmetic of Mine Transient Electromagnetic Method

矿井瞬变电磁已普遍应用于我国各大矿区的水害探查。由于适用于矿井探测空间的视电阻率算法在大量数据处理平台中还未得到及时更新,很多矿方技术人员仍在沿用传统的地面视电阻率算法,其结果的可靠性值得探讨。通过将水平电偶极子产生的瞬变电磁场沿发射回线的路径进行积分,并基于磁矩等效原理,推导了矿井空间条件下的多匝方形回线瞬变电磁场响应公式,与数值计算结果进行对比,确定其最大误差为1.5%,证明该公式是准确的。利用相同测试参数条件下矿井与地面瞬变电磁场的对比,确定前者的响应幅值为后者的2.5倍,相应的视电阻率比值为1.842,进一步表明传统的地面视电阻率值与矿井视电阻率值之间仅存在固定的比例关系,对视电阻率的趋势特征并未改变,可认为传统视电阻率算法相对可靠,对现场勘探解释的影响较小。

The mine transient electromagnetic method has been widely used to detect water aquifer in China＇ s major mining areas. As the apparent resistivity algorithm appropriated for the mine detection space in a large number of data processing platform has not yet been updated in time, most of the mine technical personnel are still using the traditional apparent resistivity algorithm of surface, thus the reliability of its results needs to be dis- cussed. The formula of the transient electromagnetic field induced by the multi - turn square loops under the mine space condition was deducedthrough the integration of the transient electromagnetic field induced by the horizontal electric dipole along the path of the emission loops and the equivalent substitution of magnetic moment. Its accuracy was proven by the maximum error of 1.5% obtained by the contrast between the analytic solutions and numerical solutions. By the comparison of the mine transient electromagnetic field with surface transient electromagnetic field under the same test parameters, it showed that the response amplitude of the former is 2.5 times that of the latter, and the corresponding ratio of apparent resistivity between the twois 1. 842, which further indicated a fixed proportional relationship between the unchanged trend characteristic of apparent resistivity apparent resistivity of surface and that of mine, and the It can be concluded that the traditional apparent resistivity algorithm was relatively reliable and had little effect on interpretation of site exploration