Numerical Simulation And Application On High Density Resistivity Image Of Underground Space Anomalous Body

Exploration of high-density resistivity method is new geophysical techniques utilized to acquire target geological characteristics by imposing the artificial electric field and identifying the current distribution on the target based on the electric differences of the target. It is an efficient, fast and collecting information-rich exploration technology and has been widely used in geological prospecting, geological disaster investigation and other project areas. But, due to factors such as space restrictions, current strength, the number of electrodes, electrode spacing, so detecting range, depth and resolution are affected.In this dissertation, forward modeling, inversion modeling, reasonable noise reduction, and project validation are used to analyze anomaly resolution of underground space, and propose how to improve the resolution of the inversion results. It would improve the practical application values of high density electrical method.Firstly, the dissertation simulates 2-D high-density electrical probe in the horizontal terrain. When the range of anomalies lateral direction (horizontal direction) and vertical (depth direction) are changed, as well as the number of exceptions, the differences of resistivity, and the interference between adjacent exceptions, then the resolution of the inversion results has been affected.Secondly, the dissertation simulates 2-D high-density electrical probe in the uneven terrain. The resolution of results affected by different devices and different terrain topography forms such as the ridge and the valley terrain. By comparison, Schlumberger device is the best device detecting non-flat terrain, and dipole-dipole device has the least detect effective of the uneven terrain.Then, different types of wavelet are used to reduce noise levels of high and low resistivity anomaly body model. In general, content of low-noise model, DB6 Wavelet and Bior2.8 Wavelet are the best choices. For models with high noise levels, the effect of two types of wavelet denoising are similar, but it’s not obvious. And for layered soils model, threshold method is the optimal choice.Finally, the dissertation studies on 3-D finite difference numerical simulation of high density electric method. It can be concluded that the accuracy and resolution of 3-D high density resistivity method’s inversion results are significantly higher than the 2-D method’s. But for deep exceptions, whose resolution will still be affected by varying degrees of high or low resistivity values, shape and size, as well as detecting parameters. So it can provide reliable basis for data interpretation of three-dimensional high density electric method.At last, the efficiency of this inversion method was further verified by project examples. The inversion results consistent with factual information, and it can be confirmed that the applicability and reliability of the content of this dissertation.