Application of GPR in urban utility detection ranging and characterization

Abstract

Keeping track of underground utilities through maps or real physical signs is essential for their maintenance and quick repairs, whenever required, without causing much obstruction to day to day life. It is not uncommon that maps are misplaced or real physical signs are destroyed. In such situations, digging and excavation becomes unavoidable during repair works. Ground penetrating radar (GPR) is one of the non invasive methods which now are being applied for detection, ranging and characterization of subsurface buried objects. GPR employs radar pulses, sends them into ground, then get back scattered energy from dielectric discontinuities in the subsurface. Frequency of antennae determine their capacity to detect and resolve the buried objects (depth of penetration is worth a mention). Hence, 400MHz and 200MHz frequency antennae are generally used for utility mapping at shallow depths up to 4 to 5 meters. GPR response to buried objects is very much dependent upon buried object locations, their constituents, their surroundings and antennae properties. It is very crucial to have a database of GPR responses corresponding to various influencing factors over their ranges of variability either by experimental or simulation studies. In the present work, an attempt has been made to generate data so as to know the dependence of GPR responses on changes in the influencing factors. Simulations have been carried out by using exclusive GPR simulation software called GPRMax. Several typical ground scenarios have been simulated and effects of various object, medium and antennae parameters on response of GPR have been studied and relationships have been established between them using response surface method (RSM). Finally, real GPR data has been compared with simulated data and interpreted.