自然电场法勘探火山岩地区地下水的研究

A STUDY OF SELF-POTENTIAL METHOD IN HYDROGEOLOGICAL EXPLORATION OF VOLCANIC AREA

多个火山岩地区找水的勘探实例表明,地表观测到的自然电位异常(简称SP)与地下非饱和区厚度相关。本文认为这种自然电位异常是由于雨水垂直向下流经非饱和区(渗流区)到达地下不透水界面引起,并提出产生自然电位异常的地下极化模型,进而根据静电场理论建立了水文地质模型与自电异常之间的理论关系。这一理论能够实现把一种波数域反演技术引进自然电位异常的反演,以便计算地下水的位置和深度。模型算例和勘探实例表明这一方法可以用于勘探火山岩地区地下水。

Hydrogeological exploration examples of volcanic areas showed that there is a correlation between the range of negative self-potential (SP) anomaly and the thickness of the unsaturated zone measured in borings. Based on this correlation, SP anomaly is assumed to be created in the unsaturated medium through which meteoric water moves downward. A polarized model has been used to interpret SP anomaly. A formula of SP anomaly produced by the polarized model has been derived analytically. Because of the SP formula, a inverse technique in wavenumber domain can be used for inversion of the SP anomaly so as to calculate the location of ground water and the depth to ground water. The model test and the exploration example show that this method can be used to explore ground water in volcanic area.