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在隐伏岩溶探测中,为实现岩溶管道引起的充电法电位水平梯度局部异常与线性或低缓区域背景场的分离,突出局部微弱异常,本文根据半无限均匀大地中,良导电球体和无限长水平圆柱体充电电位水平梯度及其一次导数剖面曲线分布特征与规律,采用两点平滑法和一阶中心差分法推导出充电电位水平梯度一次导数的近视计算公式,建立了差分滤波函数F xi+1+12()h极小值点与线性或低缓区域背景场特征点的对应关系.在此基础上,提出了线性或低缓区域背景场的线性插值公式和拉格朗日插值公式,以及局部异常与线性或低缓区域背景场划分的作图法和解析法.差分滤波函数F xi+1+12()h对充电法电位水平梯度观测误差、地质噪声具有平滑和低通滤波作用,由此差分滤波函数F xi+1+12()h确定的实测充电法电位水平梯度线性或低缓区域背景场将更为合理,实现了充电法电位水平梯度局部异常与线性或低缓区域背景场的有效分离.利用该局部异常与线性或低缓区域背景场划分方法,实际处理了桂东北越城岭山脉东部岩溶区的洛潭水库实测充电电位水平梯度异常数据,提取了受强大区域背景场掩盖了的岩溶管道产生的微弱异常,突出了岩溶病态水库漏水通道、断裂构造分布等地质信息,为岩溶病态水库的除险加固工程供了有效的处理途径和工程靶区.地质钻探工程和地下水示踪试验均验证了所研发的基于一阶差分的充电法电位水平梯度局部异常与线性或低缓区域背景场分离方法的准确性、有效性和实用性.
In the concealed karst exploration, local weak anomalies are highlighted in order to realize the separation of the local anomalies of the potential gradients of the charging method from the linear or low-lying regions caused by the karst pipelines. According to the semi-infinite uniform earth, good conductive sphere and infinite horizontal cylinder Body charge potential horizontal gradient and its first derivative profile curve distribution characteristics and laws, the two-point smoothing method and the first-order center difference method is used to derive the myopic calculation formula of the first derivative of the horizontal gradient of charge potential, and the differential filter function F xi + 1 + 12 () h and linear or slow regional background field feature points.On this basis, the linear interpolation formula and Lagrange interpolation formula of linear or slow region background field are proposed, and the relationship between local anomalies and Linear or slow region of the background field of the mapping and analytic method differential filtering function F xi + 1 +12 () h on the charging method of the potential gradient observation error, geological noise has a smooth and low-pass filtering, which differential filtering The function F xi + 1 + 12 (h) of the measured background charge level of the potential level gradient linear or slow region background field will be more reasonable to achieve the charging method potential level Degree local anomaly and the linear or slow regional background field are effectively separated.By using this local anomaly and the linear or slow regional background field division method, the actual measured charge potential level anomaly in Luo Tan Reservoir in the eastern karst area of the Yuechengling Mountains in northeast Guangxi Data, the faint anomalies produced by the karst pipe covered by the strong regional background field are extracted, the geological information of the leaking channel and fracture structure of the karst reservoirs is highlighted, which provides an effective approach for the reinforcement and reinforcement of the karst reservoirs Engineering target area.Geological drilling engineering and groundwater tracing experiments verify the accuracy, validity and practicability of the developed method based on the first-order differential method for local abnormalities of potential level gradient and linear or slow region background field separation.