Based on the partial destruction of Liqiao reservoir during Minle earthquake in Gansu province

Ground Penetrating Radar is used to study the seepage disease resulting from incompact earthfill in the course of construction. Detection results indicate that dam loam core wall is incompact

uneven and rich in cracks. The long-term seepage of the dam has caused various caves in some areas. The seepage pathway of core wall is diagnosed below the eastern and western dam crest and under dam slope road. The detecting mechanism of ground penetrating radar for seepage pathway is studied; the three development phases of dam seepage breakage and corresponding radar image characteristic are put forward.