This thesis investigates the application of guided ultrasonic waves to grout quality testing of rock bolts. Rock bolts are widely used to reinforce excavated ground in both mining and civil engineering structures. To date, opportunities for testing the quality of the grout in grouted rock bolts have been limited to the standard pull-out tests and the over-coring method. Both these methods are destructive, time-consuming and costly. These deficiencies have fueled research into the use of ultrasonic methods for testing the quality of the grout in rock bolts. However, only partial success has been achieved in these efforts chiefly due to inadequate knowledge of the characteristics of the guided waves that propagate along rock bolts. Given the slender and cylindrical structure of a rock bolt, guided waves as opposed to the conventional ultrasonic waves are excited in a rock bolt.; In this project, rock bolt specimens grouted in concrete were prepared in the laboratory in order to simulate the embedded nature of grouted rock bolts. The characteristics of guided ultrasonic waves propagating along the test specimens were then investigated using test frequencies ranging from 20 kHz to 100 kHz. The effects of varying the physical properties of the embedding concrete medium were investigated by performing the ultrasonic tests during the curing period of the concrete. (Abstract shortened by UMI.)
展开▼
