夹角和偏移距对岩溶区高密度电法响应特征的影响试验研究

高密度电法是岩溶区隐患探查的重要手段,考虑到岩溶管道走向多变、现场测线布设偏离异常体等问题,为利用高密度电法实施岩溶区溶洞及岩溶管道等异常空间分布精确探测及准确定位,开展了高密度电法的旁侧响应研究。通过构建室内水槽试验模型,采用比值处理手段,研究并探讨了不同走向、不同深度的岩溶管道以及同一埋深下的溶洞模型逐渐偏离探测断面过程中的电场响应规律。结果表明:岩溶管道与测线夹角从60°到30°的响应特征减弱幅度较从90°到60°明显;随着岩溶管道与测线之间夹角减小,探测到异常中心位置处的电阻率值逐渐变小,但其两侧电阻率值有所升高;溶洞模型逐渐偏离测线的过程中,异常区域逐渐下移但其顶部比底部下移明显。研究成果有效掌握并利用旁侧效应的特征和规律,从而为野外测线的合理布置及地质解译提供参考。

Experimental study on influence fromincluded angle and offset on response characteristics of high-density electrical method in karst area

As the high-density resistivity method is an important means to detect hidden dangers in karst area，a study is made on the lateral response of the high-densityresistivity method，so as to implement the accurate detection and correct positioning of the abnormal spatial distribution of karst cave and karst passage within karst area under the consideration of the problems of the various strike directions of karst passage，the deviation of in situ survey line layout from abnormal body，etc. Through building the model of indoor flume experiment，the laws of electric field responses during the processes of the gradual deviations of the karst passages with various strike directions and various depths as well as the karst cave models under the same buried depths from the detecting cross-sections are studied and explored by the means of ratio processing. The result shows that the decreasing extent of the response characteristics of the included angle between karst passage and the survey line from 60° to 30° is more obvious than that from 90°to 60°. Along with the decrease of the included angle between karst passage and the survey line，the resistivity value at the abnormal central position is detected to be gradually decreased，but the resistivity values on both the sides are increased to some extent. During the process of the gradual deviation of the karst cave model from the survey line，the abnormal zone gradually moves downward，however，the downward move of its top is more obvious than that of the bottom. The lateral effect is effectively grasped and utilized in this study，thus relevant reference is provide for the reasonable layout of field survey line and geological interpretation.