2019_EJRNL_PP_K_L_SIU_1.pdf
Terbatas  
» Gedung UPT Perpustakaan
Terbatas  
» Gedung UPT Perpustakaan
Electromagnetic induction is the most common technique used for geophysical survey of
underground utilities, in planning stage, prior to construction/excavation and maintenance stage
of projects. Despite its popularity and usefulness, its reliability and accuracy are nevertheless
always questionable due to coupling effects amongst the very congested underground utilities.
This work studies the disturbed electromagnetic field patterns caused by the coupling effect of
neighbouring cables and metallic pipes via a series of validation experiments in PolyU’s indoor
underground utility laboratory. The ‘fingerprints’ of electromagnetic fields are established
corresponding to different below ground conditions. 11 setups with 260 tests were designed to
study the coupling effect between a cable and a pipe. The results show that the coupling effect is
significant in the active detection of the cable. The experiment also compares the accuracies of
cable and pipe detection at different induction frequencies with reference to the accuracy levels
in the HK EMSD standard and PAS128:2014 British standard. This paper demonstrates the
importance of coupling effects in the detection of underground utilities, which should be
considered in future revision of standards.