Ultrasonic Testing of Anchor Bolts

Anchor bolts play a crucial role in supporting the power cables of the overhead catenary system (OCS) in underground train tunnels. With exposure to humid conditions and water seepage in the tunnel from wet weathers, the anchor bolts can experience corrosion and damage at an accelerated rate. As anchor bolts are embedded into the concrete tunnel, and their conditions are unknown without proper inspection of their internal bodies. This paper aims to propose an inspection process to allow technicians to perform ultrasonic testing (UT) on anchor bolts during scheduled maintenance works in the tunnel. Experimental studies using ultrasonic waves were carried out on the anchor bolts of different integrity conditions. Analytical studies conducted were then used to determine the tolerance level and decision matrix to categorize the different conditions of anchor bolts. The outcome of this study shows that there is a feasible approach to perform UT inspections on the anchor bolts.