| Summary: | 碩士 === 國立中央大學 === 地球科學學系 === 107 === The non-destructive geophysical investigation methods are widely used in geological surveys, engineering surveys or the composition of the subsurface materials. Especially, because of the high sensitivity of electrical structure, the electrical resistivity tomography method （ERT） has been widely used in near-surface geological surveys, such as hydrogeology groundwater exploration, tunnel engineering, and underground pipelines surveys. Also, combining the surface-borehole electrical resistivity tomography, we will gain more detail of subsurface information from the measured resistivity data. We operated the cross-borehole ERT measurement with the electrode configuration “Hybrid array” at Dapo elementary school locates at Taiwan, Taitung, Chihshang. With 20 electrodes at the surface and the subsurface electrodes of Dapo#2 and Dapo#6. The total data is 3129 and leaves 2300 data after removing the noisy data. Although we get better information at shallow subsurface after the data processing, the information of deeper subsurface is still hard to identify. In order to understand the spatial resolution and resolving ability of ERT method, especially cross-borehole ERT measurement, we should quantify the electrode array and survey parameters before we go field working. So we could efficiently avoid producing the artificial image. This research follows the checkerboard analysis to evaluate the accuracy of inversion results. The forward modeling method and inversion are operated by the ERT software, EarthImager 2D. We choose the electrode configurations Pole-Pole array and Dipole –Dipole array to analyze the spatial resolution and inversion results of surface-borehole ERT. The controlling measure parameter includes electrode spacing, number of wells, the distance of two wells, the grid size of checkerboard, and the structure types.
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