Three-dimensional NLCG Inversion by DC Method Based on Unstructured Grid
Direct current resistivity method,as one of the geophysical exploration methods,is widely used in mineral exploration,environmental investigation,engineering investiga-tion,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 re-search of three-dimensional resistivity inversion,actual geoelectric exploration targets,and realizes the three-dimensional nonlinear conjugate gradient inversion algorithm of unstruc-tured 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 encryp-tion 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 calcu-late 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 it-erations,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 ap-plication value.
万方数据
维普
