China Power Engineering Consulting Group Northeast Electric Power Design Institute Co., Ltd. Changchun 130021

In the construction of UHV lines in Liuzhou, Guangxi, the authors used high density resistivity method to detect underground caves, however, it is difficult to determine whether the high resistivity anomaly is the response of the gas-filled cave or the high resistivity limestone itself. On the basis of high density resistivity method, ground penetrating radar was used to further verify the abnormal fuzzy area. The hyperbolic reflection anomaly in radar result indicated that the high resistivity anomaly is derived from gas-filled cave, rather than the limestone itself.