Owing　to　exploitation　of　tunnel　and　other　underground　space,　the　structure　and　stress　form　of　the　original　foundation　soil　has　been　changed.　What’s　more,　it　also　causes　the　damage　of　foundation　soil　structure　and　the　destruction　of　the　ground　structures.　Meanwhile,　it　leads　to　engineering　accidents　and　serious　social　impact.　Therefore,　adopting　an　advanced　detection　technology　has　important　engineering　application　value　and　social　significance.　The　GPR　detection　technology　can　detect　the　underground　unknown　geological　body　quickly.　Then,　this　paper　conducts　cavity　exploration　combining　the　K62　+　0　∼　100　collapse　section　of　Kun　Yu　highway.　The　detection　results　are　used　to　guide　the　subgrade　strengthening　and　the　grouting　effects　have　been　examined　which　gained　good　application　results.　©　2016　Taylor　&　Francis　Group,　London.