School of Mines, China University of Mining and Technology
Shanxi Ningwu Yushupo Coal Industry Co., Ltd.
School of Resources and Geosciences, China University of Mining and Technology

目前，地面瞬变电磁法凭借其优势已被广泛用于煤矿水文地质勘查中，然而，在野外实际勘探中，复杂地形环境常导致发射源几何形状的改变与信号接收偏差，降低了勘探精度。为此，采用理论分析、数值模拟和实际地形数据分析相结合的方式，系统研究了复杂地形条件下电性源与磁性源瞬变电磁场的响应特征。首先，基于二阶后退欧拉离散的矢量有限元正演模拟技术，详细探讨了山峰和山谷地形位于接收点和发射源位置时，对两种源系统的影响规律。结果表明：电性源系统会出现响应变号现象，源导线位置高于周围地形时响应增强，反之则被削弱；而磁性源无变号现象，但响应变化规律与电性源类似。其次，利用实测地形数据，采用四面体网格建立与实际地形高度吻合的三维正演模型。模拟结果显示：早期响应曲线能够清晰反映地形细节，曲线形态与地形特征一致；而晚期响应则逐渐趋于平缓，体现了深部背景的影响。研究成果可为复杂地形条件下瞬变电磁法的勘探装置布设、数据采集、处理和解释提供理论指导，对提高煤矿水文地质勘探精度具有重要意义。

The ground-based transient electromagnetic method (TEM), with unique advantages, has been extensively applied for hydrogeological exploration in coal mines. However, in field exploration, complex terrains tend to cause variations in geometric shapes of transmitting sources and deviations in signals received, reducing exploration accuracy. Hence, by integrating theoretical analysis and numerical simulations with the analysis of actual terrain data, this study systematically investigated the response characteristics of electrical- and magnetic-source TEM fields under complex terrains. Using the vector finite-element electromagnetic forward modeling technique based on second-order backward Euler discretization, this study delved into the laws of influence of peak and valley terrains as locations of receiving points and transmitting sources on the two source systems. The results show that the electrical-source system suffered signal changes, with responses being enhanced in the case of the source wire position higher than the surrounding terrain and weakened otherwise. In contrast, the magnetic-source system manifested no signal changes but similar response variations. Then, based on measured terrain data, this study established a three-dimensional forward model that highly matched actual terrains using tetrahedral grids. The simulation results indicate that the earlier response curves can distinctly mirror the terrain details, with curve morphologies consistent with terrain features, whereas the later response curves gradually tended to flatten, suggesting the influence of deep structures. The findings of this study will provide theoretical guidance for exploration device arrangement, as well as data acquisition, processing, and interpretations, of the TEM method under complex terrains, thereby holding critical significance for improving the hydrogeological exploration accuracy of coal mines.

国家自然科学基金青年科学基金项目(42304085)；江苏省自然科学基金青年基金项目(BK20231086)

屈少波，朱姣，姜志海，等. 复杂地形瞬变电磁三维正演模拟与地形效应分析[J]. 煤田地质与勘探，2024，52(4)：137−151.

QU Shaobo，ZHU Jiao，JIANG Zhihai，et al. Three-dimensional forward modeling using the transient electromagnetic method under complex terrains and the analysis of terrain effects[J]. Coal Geology & Exploration，2024，52(4)：137−151.