Levee Slurry Wall Assessment Using Ground Penetrating Radar, A Case Study

Abstract

Levees are essential structures in places with high water level events. Therefore, it is important to make periodic monitoring of these structures to assess their condition. Some levees consist of slurry walls built with reinforced concrete. GSSI ground penetrating radar with 200, 400, and 900 MHz antenna was used to assess the rebar and concrete condition of the slurry wall along 300m of the Big Dam Bride levee, Little Rock, Arkansas, USA. GPR profiles indicate the deterioration in rebar and concrete from the reflections of the rebar and the differences in the rebar vertical depths which represent the change in the concrete properties. These vertical shifts in the rebar anomalies indicate that the concrete fractured and the discontinued slabs shifted upward or downward over the years, all field observations did not indicated any vertical shift or fracture in the concrete slabs, or is the presence of deterioration in the concrete above the rebar. Therefore, the deteriorated part will appear at a higher or lower levels related to the non deteriorated part. Also, non-uniform values of reflections for the same depth suggest the rebar deterioration as well. There were about 182m out of 300m of the studied levee are detroierated with various degrees of rebars and concrete deterioration. The GPR was found to be effective to detect the slurry wall's concrete and rebar deterioration. The result of this study indicates that the slurry wall of the levee is possibly unsafe and partially deteriorated.