岩溶地区地波的简化计算

我国岩溶面积约占全国总面积的八分之一。岩溶探测对于国民经济和国防建设均具有重大意义。近年来的实践证明,用钻孔无线电波法(以下简称电波法或电波勘探)探测岩溶,是一种很有希望的方法。

A SIMPLIFIED PROCEDURE FOR CALCULATINGEARTH WAVES IN KARSTIC TERRAINS

Based upon a series of researches done by earlier investigators on problems concerning earth waves, an approximate formula for calculating the lateral waves arriving from the earth (limestone) -air interface is given in this paper, with special reference to the geoelectrical characteristics of the karstic terrain. This formula is explicit in physical sense, easy to calculate, and simple for numerical inversion. The result of the numerical calculati onshows good consistence with the asmptotic expansion solution. In addition, taking into consideration of the geoelectric features of the karstic terrain, some kind of digital modelling are made for the synthesis of earth waves in terms of different combinations of electromagnetic and geometric parameters, and whereby the dependence of the amplitude ratio of the lateral to the direct waves upon the freguency of electromagnetic waves, the distance between boreholes, the depth of the measured point, and upon the electrical paramenters has been studied, indicating thus the capability of the double-hole EMmethod to obtain interference curves with apparent extremes for direct and lateral waves in karstic terrain.All inferences in this paper are drawn primarily from the geoelectrical environment of the karstic terrain, but they can be valid for other areas with low absorption media.