Abstract：Research purposes: The high and middle － low frequency ground penetrating radars have been widely used in the testing engineering quality and detecting shallow karst and the karst cave，but detecting the deeper karst cave( 15 ～40 meters) needs lower frequency ground penetrating radar in the stage of survey and design． The research on application of the combined antenna of the ultra － low frequency radar shows the ultra － low frequency radar can be used for detecting the deeper karst cave in some special cases by changing the combined frequency to make up the deficiency of the electrical prospecting．
Research conclusions: The electrical prospecting method is poor in detecting in the hard ground or rugged terrain，so the method of ultra － low combined frequency ground penetrating radar could be substituted for the normal electrical prospecting in this condition，and it could improve the precision and efficiency in the exploration of karst roadbed． The jamming characteristic of different radar echoes under the different site conditions is analyzed and the rational method is found，achieving the good results in the practical application of karst cave exploration．
李添翼. 超低频地质雷达在岩溶勘探中的应用研究[J]. 铁道工程学报, 2012, 29(3): 6-11.
LI Tian － yi. Study on Application of Ultra － low Frequency Ground Penetrating Radar in Karst Exploration. 铁道工程学报, 2012, 29(3): 6-11.
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2012, Vol. 29 
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