The research of acoustic wave non-destructive examination technology for anchoring quality of anchored bolt

The key factor to the evaluation of bolt performance is its length embedded in cement mortar and the saturation between the bolt and mortar. Therefore, the main task of testing the quality of anchored bolt is to evaluate these two technical specifications. The earlier means of anchoring test is to test the anchor pullout resistance. But there are many flaws in this approach, such as destructive, not fully reflecting the quality of the anchor bolt, the situation for cement mortar to package the reinforced bar can not be detected, and the actual length of anchor can not be detected, too. In view of this, in this paper, the technology of wave nondestructive examination of anchoring quality is employed. This technology determines quickly and accurately the anchor construction conditions, and also reduces the damage to the existing structures. The theoretical basis is the acoustic wave propagation in the anchor. Mortar saturation detection is based on the theory of wave propagation in the bar. It consists of exciting at the exposed end of the bolt, which results in elastic stress wave propagating along the bar and a reflected signal when the medium at the bottom or around the bar changes. We can determine the density of anchor position in cement mortar by the reflected signals from the sensor attached to the end of the steel. From waveform analysis, we can calculate the position of non-dense based on the two adjacent points of reflected wave. While, in the premise of fixed excitation energy, calculation of the mean square root of the amplitude of waveform behind reflex points can determine the density of cement mortar situation. It is proved by theoretical analysis and practical application that this technology is a very effective method for nondestructive testing of bolt.