关键词: 无线电波透视法, 数值模拟, 陷落柱, 断层

Abstract: The propagation of electromagnetic waves in underground media is complex. Studying the impact of coal (rock) layers and geological anomalies on the perspective of electromagnetic waves enables more accurate inference and interpretation of anomalous bodies. In this paper, a three-dimensional numerical simulation method is used to simulate the propagation characteristics of electromagnetic waves emitted by a circular antenna in coal (rock) layers encountering different types of geological anomalies (faults, subsidence columns) under full-space conditions. The following conclusions are obtained: (1) When the anomalous body is predominantly filled with air, it has a small absorption coefficient, low electromagnetic wave loss, and the contour lines of magnetic field intensity protrude outside. When the anomalous body is predominantly filled with water, the absorption coefficient increases, resulting in greater electromagnetic wave energy loss and concave curves. When filled with other media, the electromagnetic wave loss is between the two extremes, and the electrical characteristics of the anomaly area can be determined by observing the changes in field strength curves and contour lines. (2) Different shapes and sizes of anomalous bodies result in different distributions of magnetic field intensity. When the anomaly area is circular or approximately circular, the magnetic field intensity is distorted within the anomalous body and gradually returns to a normal distribution away from the anomaly, making identification more difficult. The smaller the diameter of the anomalous body, the more challenging the identification becomes. When the anomaly area consists of a linear fault, the angle between the fault direction and the tunnel affects the number of affected measurement points, making identification easier when the angle is small. As the angle increases, fewer measurement points are affected, making identification more difficult, and the fault direction can be roughly determined based on this observation. (3) Under normal circumstances, the field strength curve exhibits a symmetrical parabolic shape with the highest intensity in the middle and gradually decreasing on both sides. However, the shape of the curve varies depending on the position, morphology, and filling material of the anomalous body. When the anomalous body is large, the symmetry of the curve is disrupted, resulting in a symmetrical or asymmetrical "M" shape. Therefore, in the initial stage of data processing, the qualitative characteristics of anomalous bodies can be preliminarily determined by identifying the shape of the curve. However, precise localization of anomalous features along the ray requires further analysis using tomographic imaging to achieve a correct and reasonable understanding.