EXPERIMENTAL STUDY ON INFLUENCE OF TERRAIN FLUCTUATION TO HIGH DENSITY RESISTIVITY METHOD FOR DETECTING UNDERGROUND KARST PIPES

High-density resistivity method is effective in searching for water in karst areas. Due to complex topography condition in karst area, the high density resistivity method can be greatly influenced by the terrain fluctuation. In order to improve the prospecting its effect in water exploration, and mastering the regularity of the influence of the terrain fluctuation, this work uses a high-density micro-electrical measurement system and the copper cylinder model to simulate the karst pipe underground. It then studies the influence of terrain fluctuation on the high density resistivity method to detect the karst pipes. The results indicate that high density composite profile method and α₂ device are greatly influenced by the valley topography. False low resistance anomaly can be easily appeared in the middle valley. Rectangular AMN and rolling MNB device are less affected by terrain. The exploration depth of high density resistivity method about the anomaly can be reduced by the valley topography. When the electrode spacing is fixed, the top depth of the inversion about the flat model and valley model is less than the true anomaly, but the transverse width is greater than the true anomaly. Otherwise, the top depth the inversion about the flat model is greater than the valley model, the transverse width of the inversion about the flat model is less than the valley model.