DBPapers
DOI: 10.5593/SGEM2014/B22/S9.057

SOME REMARKS ON GEODETIC SURVEY METHODS APPLICATION IN DISPLACEMENT MEASUREMENTS AND CAPACITY TESTING OF DRIVEN PILES

Z.Muszynski, J. Rybak
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-11-7 / ISSN 1314-2704, June 19-25, 2014, Book 2, Vol. 2, 451-458 pp

ABSTRACT
In the case of conventional static load testing, the measurement of pile settlement may be affected by ground movement due to displacements of the reference beam or anchor piles. The application of direct high-precision leveling enables to provide an independent reference measurement which is free from systematic errors. This method is less accurate than the use of displacement sensors, but still provides good results. As far as vertical static load test is concerned, it is possible to make a mistake regarding the value of settlement; that however does not change, basically, the nature of the loadsettlement relationship. When the test aims at reaching a pile capacity (ultimate capacity), necessary for dynamic tests calibration, the piles keep on submerging in the ground anyway, so the dial indicators, as well as the levelling instrument, show “very much”, hence the potential inaccuracies or systematic errors are of no importance. For the purpose of the control of anchor piles extraction, geodetic survey is indispensable, as it enables one to control quickly a large number of piles, at the same time ensuring sufficient accuracy (the criterion is such: was the uplift larger than 5 mm?). Construction of an independent reference system is even more complicated when horizontal testing of a pile in a slope is considered. In a static horizontal load test, the acknowledged criterion is the value of displacement. That means that the pile load capacity is understood as the force at which the pile will get displaced at the distance of 10 mm. In this case, any underestimation of the displacement leads to an overstated value of the pile’s load capacity The research conducted at Wrocław University of Technology enabled to collect and summarize results of displacement measurements in course of foundation works [1] and static load testing of piles [3]. Some selected case studies of the use of geodetic methods in vertical (axial) and horizontal pile load testing were presented in the paper.

Keywords: axial load test, lateral load test, geodetic measurements, displacements