As the groundwater disaster conceals behind the reinforced concrete and the irregular shape of cavity and the existence of other factors

such as moisture

air

grout and soil

it is hard to detect and study this issue exactly. This paper analyzes the causes of defects existing behind the tunnel lining

illustrates the theory and method of making non-destructive test on tunnel lining quality by using geological radar and carries out a health consultation on a tunnel. By processing and analyzing field data

the following functions can be performed: detecting the thickness of concrete lining accurately

determining the distribution position and quantities of rebar and grid steel and searching for the existence of cavity and uncompacted area behind the lining

especially on lining arch top. We also apply the method of morphology to extract the feature of liner image. We get the liner boundary line and the waterlogging area more intuitively by wavelet analysis

and find the anomalous points in the liner. It is proved that geologic radar is a feasible measure to inspect the concrete structure of tunnel. Adopting hole-drilling method to make verifications of geological radar detecting results

the results are quite satisfying.