不同深度谷地对高密度电法探测地下岩溶管道的影响试验研究

Experimental Study on the Influence of Different Valley Depth on the High Density Resistivity Method to Detect Underground Karst Pipeline

高密度电阻率法在岩溶山区找水具有较好的效果,但岩溶区找水往往位于谷地,地形条件复杂,谷地深浅不一,高密度电法受谷地地形影响较大。为了提高岩溶区高密度电阻率法找水的探测效果,掌握不同深度谷地对高密度电阻率法影响的规律,采用高密度电法微测系统,利用铜柱体模拟地下岩溶管道,研究不同深度谷地对高密度电阻率法探测岩溶管道的影响。研究结果表明:在谷地模型中,当电极距、谷地深度相同时,α2装置对确定异常体的顶部埋深优于矩形AMN装置及滚动MNB装置,而矩形AMN装置及滚动MNB装置对异常的定位及确定异常体的大小优于α2装置。电极距相同时,随谷地深度增加,反演异常体横向宽度增大,埋深减小;且越来越偏离真实异常体;随谷地深度增加,高密度电阻率法能探测的有效异常体的深度减小;在谷地较深的高密度电阻率法勘探中,为了获得较好的探测效果,应适当增大电极距的布设。

The high-density resistivity method is effective in searching for water in karst areas, but the water ex- ploration in karst area is often located in the valleys which have complex terrain and different depth, the high density resistivity method is greatly influenced by the valleys terrain. In order to improve the prospecting effect of the high density resistivity method in water exploration, and then mastering the regularity of the influence of high density resistivity method with the different depth of valleys, a high-density micro-electrical measurement system and the copper cylinder model were used to simulate the Karst pipeline underground, and then study the influence of valleys terrain on the high density resistivity method to detect the karst pipeline. The results indicate that when the electrode distance and the depth of valleys have a fixed value, α2 device is superior to the rectangular AMN device and the rolling MNB device for determining the top depth of the abnormal body, rectangular AMN device and rolling MNB device are better than α2 device for locating the anomaly and determining the size of the abnormal body. When the electrode distance has a fixed value, with the increase of the valley depth, the lateral width of inversion abnormal gradually increases, the buried depth of inversion abnormal gradually decreases, and the inversion abnormal increasingly deviate from the true anomaly. The exploration depth of high density resistivity method about the a- nomaly can be reduced by the increase of the valley depth. When using high-density resistivity method in water exploration in the deep valley, in order to obtain better detection effect, it should be appropriate to increase the distance of electrodes arrangement.