Estimation of length and condition of piles
At realization of construction works with use of pile driving important the question on length and condition driving into a ground of piles is. Sometimes, in infringement of technology, top piece of pile is cut off, and how many of it there remained in ground, anybody know can not. Besides the piles sometimes collapse, and it is necessary to know about it.
These tasks may be decided with the help spectral flaw detection. As an example we shall consider the measurements which have been carried out on several ferro-concrete piles, located on a line of a tunnel shield of a collector on Sinopskaya embankment. All piles are ferro-concrete, diameter 0,35 m, length free from a ground of a part - near 1 m. With the help of spectrum-acoustic flaw-detection methods the estimation of length of piles was made.
In figure are given spectrum of signals of the response of piles on shock influence. On an axis y - the sizes of object in meters (are postponed according to the formula on title page), on an axis x - good quality of sounding (Q) . On the specially selected samples the speed of shear fluctuations in a material of piles was defined.
On the basis of the analysis спектрограмм it is possible to specify the following (all sizes are counted from the end, taking place above a ground, of piles):
- The pile 1 has length 6,7-6,8 m and is broken in two places - on distance 5-5,5 m (material of a pile is shattered, the presence some cracks) and on distance 2,6 m - crack is possible.
- The pile 2 has length about 6,5 m. Extremum, appropriate to this size, is expressed very poorly, as the pile has a crack on distance of 3,3 m.
- The pile 3 has length 6,5 м and crack on 4 m.
- The pile 4 has length 5,3 м and fractured zone on 1,7 m.
The least destroyed object is the pile 4.