充水溶洞特征的高密度电阻率法反演分析研究

摘要

In high-density electrical prospecting,karst caves may show different electricity resistivity (ER) characteristics due to the nature of cave fillings.When a cave is empty,its ER value appears extremely high,when being completely filled with water this value could be very low.However,for an unsaturated karst cave,the resistivity range is difficult to judge via ER data interpretation.By constructing different models with various cave moisture contents,forward modeling using the method of least square at geoelectric sections were conducted,compared with the different geoelectric response characteristics of their inversion imaging model.The results showed that the resistivity of water-bearing karst cave decreases with increasing water content.On the geoelectircal section the range of low resistance expanded with the amount of water increased,which was strongly distinguishable.Exploration data derived from the field work further has verified the validity of the simulated results shedding light on the significance of the model application and a better understanding of electrical analysis method for underground cavern detection.%在高密度电法勘探中,不同性质的溶洞其反演电阻率特征有差异,溶洞为空洞时反演电阻率表现为高阻,充满水时表现则为低阻,而充水溶洞的电阻率反演特征很难判断.文章通过构建不同充水程度的溶洞模型进行正演模拟,利用最小二乘法对模型的地电断面进行反演,对比不同反演成像模型的地电响应特征.结果表明,充水溶洞的电阻率随溶洞充水量的增加而减小,低阻的范围随着水量的增加而不断扩大,其可分辨性强.野外探查资料进一步验证了模拟结果,所获得的认识对地下溶洞的电法探测分析具有一定的指导意义.