Nondestructive testing of grouted bolts system

This paper presents a new technique based on acoustic frequency stress wave (AFSW) technology and nondestructive pullout test (NDPT) that can be used for non destructive quality testing of bolting systems.In the light of the dynamics of grouted bolt system (GBS) and kinematics of AFSW,the relationship between reflective character phase and grouted condition,as well as the relationship between wave energetic attenuation and anchored length is analyzed.The reflection features and the attenuation laws of the AFSW are further investigated through laboratory experiments,from which an express inspection method using the AFSW is proposed.Also describes curve characteristics of pullout test and the development of testing instrument that can auto plot pullout curve and autoalarm when the GBS approaches to failure.At the same time, grading standards for anchoring quality inspection are suggested.Their results are confirmed by field tests at first coal mine of Panji.Results show that this new technique and method is practical and effective to conduct large scale quality testing,valuable to ensure the reliable safety for bolting.