Detection of Diaphragm Wall Defects Using Crosshole GPR

In this paper we discuss the implementation of crosshole ground-penetrating radar (GPR) method in diaphragm wall defect detection. The construction process of a diaphragm wall panel is introduced and different types of defects including crack, void, sludge accumulation, joint leakage, and joint split are summarized. The zero-offset profiling (ZOP) survey is advised to be carried out to quickly locate anomalous zones in diaphragm walls, followed by a multi-offset gather (MOG) survey to characterize the exact position, size and shape of defects. Numerical simulations are performed to analyze ZOP and MOG data of each type of defects. Results show that the crosshole GPR is an effective tool for diaphragm wall defect detection.