Keywords: strains, special measurement, displacement, computer monitoring, load test, piles, geotechnical engineering.

In soft soil foundation must be strengthened with piles. Problem is always local, so measurement must be done on working location. Building company can only guess the quality of piles support. Laboratory for electrical measurement on Faculty for Electrical Engineering and Computer science and faculty for civil engineering developed special measurement of the load capacity of pile. Strains in the pile were measured to depth of 15-m pile with straingagues on distances of 1m and vertical displacements of the pile were measured with inductive sensors during load test. Measurements indicated the upper load limit of the pile and behaviour of the pile during load test.

For measurement was used metal channel with straingagues, which was fixed to the metal structure of a pile. Axial forces and vertical displacements of piles were monitored with specially developed software. Duration of a load test of piles was 12 hours. Results of measurements showed critical loads on which soil support was broken. Typical force distributions and displacements are presented in an article.

For pile testing was used the concrete plate builded on six piles. Under the plate was test pile. Pile was loaded with hydraulic system inserted between the plate and pile. Because of the possibility of a returned displacement of a plate, vertical positions of a plate were observed with the geodetic. The results showed that the displacements on the plate were in the minimum values.

Measurements were done successful in very robust weather and working conditions, but protection of a straingagues must be improved, since some straingagues were destroyed. Measurement method with a construction of a metal channel and design of supported software were verified as good solution. Results were good enough to verify a load capacity of a pile's in a tested soil.

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