Optimization of resistivity tomography data for hardened sites based on ratio method

On the basis of discussing the effect of different resistivity and thickness of concrete hardening layer on target detection, a ratio method based on distortion correction principle and considering isolation coefficient to reduce the effect of hardening layer shielding is proposed. The results of numerical simulation test and indoor flume test show that the maximum permissible error of isolation coefficient should be less than 1% when the ratio method is used to correct the original collected data. When the ratio of hardened layer thickness to electrode distance is less than 1, the identification ability of target occurrence can be improved obviously after the ratio method is used to correct. However, when the thickness of the hardening layer reaches twice or more the electrode spacing, the ratio method does not achieve good results. The detection example of flood control project in Zhangxi section of Huanggan City, Dongzhi county shows that the detection effect of the modified ratio method is similar to that of the adjacent unhardened pavement, which obviously weakens the influence of hardened layer and obtains more reliable. This method improves the discriminability and application range of resistivity tomography and is of great significance for the development of fine near surface detection.