EVALUATION AND ANALYSIS OF BEARING CAPACITY OF BORED PILES AND DEEP-LAID PILE-BARRETTE FOR A HIGH-RISE BUILDING ON LOOSE GROUNDS BASED ON CALCULATIONS AND FIELD TESTS

Abstract

The study describes the standard procedure of the assessment of the bearing capacity of piles by field methods used in the Russian Federation. Basing on the example of an experimental deep-laid foundation pile (length L = 65 m, diameter D = 1.2 m) intended for a high-rise building designed for a thick layer of loose ground the study demonstrates the structure of a loading system on site and the results of static tests of piles in comparison with the results of analytical and numerical calculations. On the same construction site an experimental barrette-pile of rectangular cross-section measuring 3.3 x 1.1 with a length of 65 m was installed with the base in solid Protero­zoic clays. The pile test was carried out using Osterberg cells. For this purpose in the process of the installation of the pile strain gauges were mounted in its reinforcing cage at 9 levels. The test barrette-pile was carried out in two stages. On the first stage a standard test of the whole pile in the top-down direction was performed (Top - Down). On the second stage, after reaching the maximum possible load, the “O - cell” element test was performed trans­mitting the load in two directions (up and down). “O - cell” was located at a depth of 50 m in the layer of blue- stone. The article contains the graphs of the movements of pile from under the load applied on the first and second stages of the tests and the general assessment of the load-bearing capacity of the barrette-piles by different methods