Application of Ground Penetrating Radar technnology in investigating the hidden defects of earth dam

Ground Penetrating Radar(GPR) technology works on the principle that the character of electromagnetic wave is different when the wave travels in different media,and it has many advantages such as rapid, non destructive and continuous investigation and low cost,thus GPR technology is effective at present in investigating the hidden defects of reservoirs, dam and cut off wall. Based on a case study of investigating the hidden defects in an earth dam with GPR, the methods and results of application of GPR technology to monitoring the form and buried depth of culvert, the shape of gap, the shape and integrity of cut off wall in earth dam are presented. The selection of electromagnetic wave speed range in earth dam and the variation of the antenna frequency with investigating depth and resolution rate are also presented,and the radar wave characters of the different hidden defects of earth dam are revealed.