基于非结构网格的直流电法三维NLCG反演研究  

Three-dimensional NLCG Inversion by DC Method Based on Unstructured Grid

作　　者：秦高升 肖晓[2] Qin Gaosheng;Xiao Xiao(CNNC Research Institute No.230,Changsha Hunan 410007,China;School of Geosciences and Info-physics,Central South University,Changsha Hunan 410083,China;Hunan Engineering Technology Research Center for Evaluation and Comprehensive Utilization of Associated Radioactive Mineral Resources,CNNC Research Institute No.230,Changsha Hunan 410007,China)

机构地区：[1]核工业二三〇研究所,湖南长沙410007 [2]中南大学地球科学与信息物理学院,湖南长沙410083 [3]核工业二三〇研究所湖南省伴生放射性矿产资源评价与综合利用工程技术研究中心,湖南长沙410007

出　　处：《工程地球物理学报》2024年第3期473-483,共11页Chinese Journal of Engineering Geophysics

基　　金：中国核工业地质局项目(编号:202231)。

摘　　要：直流电阻率法是矿产勘查、环境调查、工程勘察等领域应用广泛的地球物理勘探方法之一,目前反演方法仍以二维反演为主,而实际地电勘探目标体均为三维结构,二维反演容易受旁侧效应影响。基于上述问题,本文展开了三维电阻率反演研究,实现了非结构化独立网格的三维非线性共轭梯度反演算法。非结构独立正反演网格既能适用于三维非平坦地形,可以实现网格的局部加密,又能克服正反演嵌套网格和同套网格的弊端;非线性共轭梯度法运用伴随原理不需要计算灵敏度矩阵,节约了计算资源和计算时间。程序对双立方体模型进行反演,经过100次迭代,misfit达到8%,反演重构异常体形态、位置与模型较为吻合,最后程序对某高速隧道塌陷区实测数据进行反演,通过与BERT2.0反演结果进行对比,证明了反演解释效果具有实际应用价值。Direct current resistivity method,as one of the geophysical exploration methods,is widely used in mineral exploration,environmental investigation,engineering investigation,etc.But the two-dimensional inversion,as the current main inversion method is liable to be affected by side effects.Based on the above problems,this paper carries out the research of three-dimensional resistivity inversion,actual geoelectric exploration targets,and realizes the three-dimensional nonlinear conjugate gradient inversion algorithm of unstructured independent grid.The unstructured independent forward and inverse mesh not only can be applied to the three-dimensional non-flat terrain,but also can realize the local encryption of the mesh,and overcome the disadvantages of the forward and inverse nested mesh and the similar set of mesh.The nonlinear conjugate gradient method does not need to calculate the sensitivity matrix by using the adjoint principle,which saves computing resources and computing time.The program performs inversion on the bicube model,and after 100 iterations,the misfit reaches 8%.The inversion reconstructs the shape and position of the abnormal body,which is in good agreement with the model.Finally,the program inverted the measured data in the collapse area of a high-speed tunnel,and compared it with the BERT2.0 inversion results,proving that the inversion interpretation effect has practical application value.

关 键 词：电阻率法 三维非线性共轭梯度反演 正反演独立网格 非结构网格 

分 类 号：P631.3[天文地球—地质矿产勘探]