Non-destructive Test And Model Experiment Of Anchorage System Based On Dynamic Response

It is indubitable of advanced Nature, reliability and economy of geotechnical anchoring technology. However, because of materials, construction, geological conditions and other factors, there is bound to be much damage in anchor structure of the system during the construction process. For the most rock bolts in geotechnical engineering, the quality of anchorage, the anchor length is consistent to design length or not, the quality of grouting, that is, whether the bolt could play an efficient role is very important for geotechnical reinforcement project. Therefore, the problem of damage identification, quality diagnosis and real-time detection and reinforcement, are of widespread concern to the geotechnical field. At present, most detection on anchorage quality is stayed in the step of using fluid pressure operated jacks, which needs too much work and time, and of the most important thing is that this method will do a lot of perturbation turbulence on rock mass and weakens the reinforcement action. As a result, a new detection method of the quality of anchorage, which could meet the needs of large-scale construction, is required to make up or even replace traditional method, and this is also an urgent key technical issue of geotechnical strengthening engineering.Based on summarizing literature information at home and abroad, the paper educed the physical mechanism of wave diffusion, attenuation in the bolt body, wave energy distribution in anchored section and the main reason of different wave velocity in anchored section and the reflection at the bolt bottom through theoretical analysis. The anchorage quality problem is discussed in many ways to study the safety quality assurance system of the anchorage system. The main conclusions of this paper include:(1) According to studying wave diffusion rule at anchoring system, energy distribution and attenuation law of wave elastic in anchoring system is gained to provide an important theoretical basis for the nondestructive testing of anchorage quality.(2) A finite difference software FLAC is used to simulate the dynamic testing signal of anchoring system for the first time. According to numerical simulation research on anchoring system under the conditions of the typical excitation frequency and representative vibration load, it is shown that when the stress wave transmits in anchoring system, its waveform attenuates faster along with rising excitation frequency, and also along with increasing vibration load.(3) According to study on experiment, it is revealed that there was a negative correlation between the bond strength(saturation of the anchor) of bolt body with the adhesive (cement mortar) and concretion velocity, the concretion velocity is slower with the better anchorage quality, is faster with the worst anchorage quality, and its tendency values are the wave velocity of reinforcing steel bar and anchorage medium.(4) Wavelet analysis and wavelet packet analysis are used to deal with the detect signal. When using wavelet analysis to dispose detect signal, "db4", "coif4", "sym4" wavelet are applied separately to multi-scale decompose signals, it is shown that low-frequency reconstruction signal (denoise signal), which used "db4" wavelet to process signals, has the best approximation to the original signal, and can reflect the characteristics of the original signal better; and the reconstruction signal of highest-scale decomposition coefficient could reflect the defect information. Wavelet packet analysis is an abundant means to wavelet analysis, and it played better at high-frequency information subdivision.