CRACK DETECTION USING TIME-DOMAIN WAVE-PROPAGATION TECHNIQUE

The main objectives of this paper are to determine if it is feasible t o detect and size cracks with the time-domain wave propagation techniq ues and to recommend the best field-test configuration to be used. The focus is on the geotechnical and geoenvironmental applications. A fin ite element program was used to model a cracked medium. Several parame ters were considered-the Location of source and receivers relative to the crack, the depth of the crack, the width of the crack, and the dur ation of the source impulse. Major parameters that significantly affec t the waveforms were identified by performing a sensitivity analysis o n each parameter. The most significant feature that can be used to pre dict the crack is the existence of standing wave energy detected in th e waveforms from receivers located relatively close to the downstream end of the crack. The best test setup is obtained when the source and one receiver are located close to the crack on one side of a crack and a second receiver located on the opposite side of the crack at a dist ance from the crack.