Mapping of subsurface utility and methodology for detection of soil compactness using ground penetrating radar

Abstract

The rapid urbanization development leads an aging underground infrastructure increasing demands on contractors and engineers to design and install utilities in crowded right-of-way. In the subsurface stratigraphic column (stratum), information retrieval of existing underground infrastructure from known database record is commonly less accurate and incomplete. This study investigates the use of Ground Penetrating Radar (GPR) as non-invasive with cost-effective geophysical methods to develop more complete and accurate subsurface utility map in cadastral database system to improve subsurface utility project designs and management. Focus of this study emphasizes on the accuracy of subsurface utilities position detected by GPR technology. GPR has been widely used in geological and civil engineering works, particularly in determining the location of subsurface utility, rebar, and even archaeological artifacts underneath ground surface. Nevertheless, GPR research barely investigates subsurface soil compactness. Subsequently, this study has focused on developing a technique in detection of the road soil compactness using GPR imaging. Emphasis of this work is on modeling the GPR backscatters return by means of comparison between newly completed excavated road and non-excavated road. The results indicate non-compact and compact roads are distinguishable by distinct mean vector of GPR backscatters and this is proved by analysis of variance (ANOVA) test where the Ftest is greater than Fcritical at 95% confidence level. Hence, GPR imaging is an effective technique for detecting and mapping subsurface road compactness especially in urban post-excavated roads.