利用水下电阻率层析成像技术探测坝址岩溶溶洞

Detection of karst caves at dam site using underwater resistivity tomography imaging technology

内河航运和水电开发工程在推进社会进步中发挥了重要作用,然而部分河底岩溶溶洞广泛发育,严重影响工程选址及建设。提出水下电阻率层析成像探测方案,并将该方法应用于广东东江下矶角航电枢纽工程,共布设6条700 m长横跨江面的测线,单个水底电缆排列包含40个电极,极距5 m,相邻排列重复观测长度为100 m。反演得到的三维电性结构刻画了高阻砾石层、低阻砂岩和高阻灰岩等关键地质单元,结合已有钻孔资料划分出多个隐伏溶洞靶区。水下电阻率层析成像施工难度大,正反演计算复杂,研究成果可为后续电阻率层析成像和水下灾害地质异常体探测提供参考。

Inland waterway transportation and hydropower development projects play an important role in promoting social progress.However,the widespread development of underwater karst caves has seriously affected the site selection and construction of such projects.This paper proposes an underwater resistivity tomography imaging detection scheme,which is applied to Xiajijiao Navigation and Hydroelectric Hub Project in Dongjiang,Guangdong Province.A total of six 700-meter-long cross-river survey lines are laid out,with each underwater cable arrangement containing 40 electrodes spaced 5 meters apart,and adjacent arrangements repeat observations every 100 meters.The inverted three-dimensional electrical structure delineates key geological units such as high-resistance gravel layers,low-resistance sandstone and high-resistance limestone,and multiple concealed karst cave target areas are identified in combination with existing borehole data.Underwater resistivity tomography imaging poses great construction difficulties and involves complex forward and inverse calculations,the research results can provide references for subsequent resistivity tomography imaging and underwater geological anomaly detection.