三维电场直流电阻率边界单元法地形改正

摘要

It is difficult to interpret DC electrical prospecting data which were easily Influenced by the terrain.In this pa-per,the solid angle of the ground grid nodes for the numerical calculation of formula were rigorously deduced,3D topography effect of the DC electric field were calculated by the boundary element method using fortran Language.The results of ridge ter-rain of 900 angular domain show the relative error of potential and apparent resistivity are less than 5 percent and verify the cor-rectness of the algorithm and program.3D topography effect were analyzed in valley terrain by 2D sections.In the design mode,when the lateral distance from the cross section to the main cross-section greater than 24m,the maximum value of the topographic effect less than 5% .%电法观测易受到地形的影响，给资料解释造成困难。这里对数值计算中地面网格节点的立体角（ω）公式进行了严格地推导，利用边界单元法对三维直流电场的地形影响进行了计算并编写了程序。90°角域山脊地形算例表明，解析解与数值解的电位及视电阻率相对误差小于5％，验证了算法及程序的正确性。实例计算了3D山谷地形2D观测剖面的地形效应，当旁侧剖面与主剖面距离大于24 m时，地形效应最大值小于5％。