Abstract: Along the middle highway, Haikou to Tunchang in Hainan Province, there is 7-kilometre across the basalt region, in which geological situation is complex, and rock melt hole are developed. Finding out the distribution and the size of underground cavity is the base to proceed the engineering treatment, and it is of great importance to ensure the quality of the engineering constructions. Because of the differences between underground cavity resistance and surrounding rock resistance, it was feasible that the high-density electrical method was used to detect the underground cavity and the distribution of the underground cavity was judged by the resistivity data image which showed the high impedance. The field testing results are identical to the field survey results, so it indicates that the high-density electrical method is suitable for detecting the cavity in basalt area.

Key words: high-density electrical method, basalt, underground cavity, field test

摘要： 海南省中线高速公路海口—屯昌段沿线近7 km穿越玄武岩地区，地质情况复杂，岩熔空洞发育。查明地下空洞的分布和大小，是进行工程处治的基础，对确保工程建设质量具有重要意义。由于地下空洞与围岩电阻存在着差异，所以用高密度电法对地下空洞进行现场探测，并通过电阻率数据云图中显示的高阻异常判断地下空洞分布情况的方法是可行的。现场测试结果与现场调查结果较吻合，表明高密度电法可用于玄武岩地区的地下空洞探测。

关键词: 高密度电法, 玄武岩, 地下空洞, 现场测试