Propagation Characteristics of Ultrasonic Guided Waves in Grouted Rockbolt Systems with Bond Defects under Different Confining Conditions

A rockbolt acting in the rock mass is subjected to combined action of pull-out load and confining pressure, bond quality directly affects stability roadway cavern. Therefore, this study, pressure are applied grouted systems with defects by a numerical simulation method, detected ultrasonic guided waves study propagation law defective rockbolts under pressure. The results show that length location can be Under no load, increasing low-frequency part wave frequency increases, high-frequency decreases, weakening effect on increases. existence cannot change strengthening same or