Research On Electrical Resistivity Tomography And Its Applications

Electrical resistivity tomography has been playing a more and more significant roles in resource exploration, hydrogeology surveys, engineering geology surveys, and environment geology surveys. Borehole-to-surface, surface-to-borehole and cross-hole resistivity methods have been developed by a transmited current source installed at subsurface and received on surface or subsurface, and there is more information in depth obtained from inversion of subsurface current source data sets. Throughout the literature, the three dimensional forward and inversion procedures are developed by nonlinear conjugate gradient method. In order to interpret field geological models, there are groups of numerical simulation and synthetic resistivity model tests employed for discussed the several influences in resistivity modeling and inverted subsurface resistivity distribution. Generally, the forward and inversion procedure applied in field study data interpretation and achieved better effects.Throughout the literature, the forward procedure with multiple points current source in different depths is developed by finite difference method. By discretization of the governing equation, a large-scale sparse matrix developed and the solution of equations obtain by Gauss-Seidel and ICCG methods. The influence of extending the study region and the lateral and bottom boundary in resistivity modeling are discussed by numerical simulations. By synthetic resistivity model tests, comparison of the Gauss-Seidel and ICCG methods used in modeling illustrated that the ICCG method is higher in efficiency. Then, the optimal modules are integrated for forward procedure and activate the next inversion stage.For the three dimensional resistivity inversion, a minimum structure inversion algorithm with nonlinear conjugate gradient techniques presented in borehole-to-surface and cross borehole resistivity tomography with pole-pole array and dipole-dipole array. Based on previous researches, a fixed dumping and free dumping with the inverted iteration go on by are presented in inversion procedures. What is more, the parallel methods are used in forward and inversion modules with multiple current sources. Moreover, the speed of model calculation is enhanced by implementation in parallel processing mode. The efficient algorithm is the key of efficient processing for dealing with a large amount of data sets and real-time imagery.Eventually, the forward fitting method has been used for interpretation of the residual field data sets by forward procedure. Moreover, electrical resistivity tomography(ERT) was carried out continuously for ten days to monitor rainfall infiltration along a potentially hazardous hillslope at the Jieshou Junior High School in Taoyuan, Taiwan. In addition, observations indicate that real-time ERT is effective in monitoring subterraneous rainfall infiltration, and thereby in estimating the stability of a potential landslide body. The ERT method is also used for mineral exploration at Abag Banner and Hexigten Banner in Inner Mongolia, China and receired satisfactory results.