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Experimental study on stress wave method for detecting anchorage quality of anchor cable

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Abstract

The stress wave method is difficult to be applied to obtain effective stress wave signal that reflects the section change of anchorage body in the long anchor cable. Based on the actual models of anchorage body with three special types, i.e. full-length grouting anchorage body, full-length grouting anchorage body with existence of defective segment, and non full-length grouting anchorage body with existence of free segment, and using two stress wave excitation modes, i.e. stress wave signal exciting respectively on top or bottom of anchor cable, the reliability of stress wave method to detect anchorage quality was verified through comparing the theoretical vibration velocity of the stress wave with the measured ones. Then, by combining the above two stress wave excitation modes, the feasibility of stress wave signal exciting simultaneously on top and bottom of anchor cable to detect anchorage quality of anchor cable was studied. The results show that the excitation mode of stress wave signal simultaneously on top and bottom of anchor cable can effectively detect anchorage quality of anchor cable, and signal received on top of anchor cable in this mode is the stress wave signal with the shortest propagation path for reflecting change positions of anchorage body sections. Meanwhile, the two kinds of stress wave signals are suggested to adopt different frequencies to distinguish stress wave signals exciting respectively on top and bottom of anchor cable.

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... This technique uses resistance strain gauges, differential resistance strain gauges, steel strings, and hydraulic pillows. On the other hand, the non-contact methods utilize acoustic frequency stress waves, electromagnetic and infrared radiation monitoring, etc. [7,8]. The sensitive electromechanical components have been widely adopted. ...
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