Study On Nondestructive Testing Technique Of Anchor Rod Construction Quality In Slopes Of Highway

Bolt anchoring grid beam is used extensively at mountain area in the southwestern of China as a high slope reinforcement measure.Anchor rods in freeway has being used on a large scale,for example, in Meng-Xin Expressway, which the subject bases on ,there are 745.1Km Anchor rods and 167.4Km anchor cables on total. Anchor rod is a concealed work ,and the detecting means of its anchoring quality remain relatively laggard. Due to contrived or geological conditions, the length of anchor rod is not enough or grouting is not full, and some other defects seriously threaten to the safety of slope engineering, but the traditional means of detection could not control those effectively. in such circumstances, the nondestructive testing technology becomes one of the most promising methods now. This paper focus on the research of sonic-frequency stress wave reflection method in testing construction quality of slope bolt . Through systematic theoretical analysis and testing in the field, the paper gets some major achievement as follows:(1) After analyse mechanical principles of bolt anchoring, the length of bolt construction and grouted density are determined as the main indexes of nondestructive testing on bolt construction quality.(2) The research on the reflection-transmission principle and attenuation theory of sonic-frequency stress wave, provides the theoretical foundation for the quality inspection of anchorage system; In order to test the slope bolt,which is longer than other ones generally, suitable frequency range of wave has been choosed.(3)By means of the analysis of the discrete parameters models on a single degree of freedom system and the distributed parameter system, the mathematical models,includding transient response for dynamic test of complete anchoring system, vibration velocity response and vibration acceleration response are come out,and the results can direct the detection work of anchor.(4)It can provides effective methods to identify the characteristic signals that use time-domain analysis, frequency-domain analysis and wavelet analysis to process and analyse original signals.(5)The suitable strike-vibration mode is selected through slope test. after the comparison of the acquired signal in all cases, the quality evaluation criterion of Anchorage are determined based on the analysis of the waveform, and the technique was applied to the slope bolt testing projects of Meng-Xin expressway specially.