Q: What is the difference between fixing the magnetic card holder (connecting sensor) to the anchor and fixing it to the steel strand when performing qualitative inspection of grouting density? If it is fixed on the anchor, what effect does it have on subsequent data processing? How to avoid it.
A: Fix the sensor on the anchor. The frequency of the signal received by the sensor at the far end (the other end of the excitation) will generally decrease, and the amplitude of the first wave will increase compared with the end of the strand, but it will be received. The signal quality will be much better. This is beneficial to the analysis of the 'full-length wave velocity method', and it is necessary to pay attention to the influence of the 'transfer function method' and the 'full-length attenuation method' on the results of the most comprehensive test (the grouting index will decrease). Therefore, the sensor is fixed at the anchor. When the position of the most comprehensive grouting index is determined, the analysis results of the 'full-length wave velocity method' are mainly used.