基于高密度电法的镇雄五德天坑岩溶结构识别与空间分布特征研究

Study on Karst Structure Identification and Spatial Distribution Characteristics of the Wude Tiankeng in Zhenxiong Based on ERT

摘要: 高密度电法具有探测效率高、分辨率高及电极布设灵活等优势，在岩溶结构识别与地下空间探测中应用广泛。为查明镇雄五德天坑区岩溶结构形态及空间分布特征，本文布设二维高密度电法测线开展系统探测，并结合电阻率剖面解译与区域地质资料分析，确定了基岩界面起伏及岩溶发育部位。在此基础上，对多测线数据进行三维综合处理，通过反演成像、三维可视化及多尺度切片分析，系统刻画岩溶结构的垂向特征与平面展布，圈定岩溶发育强烈区及潜在溶洞范围。结果表明高密度电法可有效识别由溶洞及破碎带引起的低阻异常，识别出A1、A2两处典型异常；基于L1~L8测线的三维联合反演，揭示了天坑北侧岩溶通道的空间展布，并准确推断边缘塌陷带位置；岩溶发育受NE向构造裂隙及碳酸盐岩层理共同控制，地下水活动对岩溶扩展及天坑演化具有重要作用。

Abstract: Electrical resistivity tomography (ERT) offers advantages including high detection efficiency, high resolution and flexible electrode deployment, and have been widely applied in karst structure identification and subsurface exploration. In order to investigate the morphology and spatial distribution characteristics of karst structures in the Wude Tiankeng area of Zhenxiong, a series of two dimensional ERT survey lines were deployed for systematic detection. The undulation of the bedrock interface and the locations of karst development were identified through the interpretation of resistivity profiles combined with regional geological data. On this basis, three dimensional integrated processing of multiple survey lines was conducted. Through inversion imaging, three dimensional visualization and multi scale slicing analysis, the vertical characteristics and planar distribution of karst structures were systematically characterized, and zones of intensive karst development as well as potential cave ranges were delineated. The results indicate that ERT can effectively identify low resistivity anomalies caused by karst caves and fractured zones, and two typical anomaly zones designated as A1 and A2 were recognized. The three dimensional joint inversion of survey lines L1 to L8 reveals the spatial distribution of karst conduits on the northern side of the tiankeng and enables accurate inference of the marginal collapse zone. Karst development is jointly controlled by northeast trending structural fractures and carbonate rock bedding, while groundwater activity plays a critical role in karst expansion and tiankeng evolution.