PILE TESTING METHODS PRIOR TO RECONSTRUCTION OF BUILDINGS

Abstract

This article presents the methods developed to test piles located in buildings under operation. The first testing method allows preserving the stress-strain state of the soil containing a pile, which has been formed during the operation of a building, thus increasing the reliability of the pile load testing. It is achieved by making two notches at opposite corners of the pile shaft, a hydraulic jack is installed in each notch, the reinforcement in two other corners of the pile shaft is cut, and the pile is separated from the pile cap by the tension of the remaining part of the pile shaft at the start of static loading. During the test, the bearing capacity of the pile, which was tested using the proposed method, was from 5 % to 7,1 % greater than the one of the piles tested according to GOST 5686-2012. The second testing method takes into account the influence of the adjacent piles on the tested one. It is achieved by installing deformation measuring devices (extensometers) on the tested and adjacent piles before separating the pile from the cap, which makes it possible to measure the changes of the strain state of the pile shaft during the test, as well as to determine the influence of the adjacent piles on the tested one. Also, the tests determine the actual load influencing the tested foundation pile, which is obligatory, when it comes to developing an engineering design of a reconstruction project. The proposed methods of the static load testing in operated buildings can be used for investigations prior to reconstruction and technical upgrades of operated buildings.