EXPERIMENTAL STUDIES OF THE INTERACTION OF BORED PILES WITH HARD CLAY SOILS DURING THE CONSTRUCTION OF LAKHTA CENTER

The article presents the results of testing bored piles with a diameter of 2 meters and a length of 55 and 65 meters during the construction of the Lakhta Center tower. The tests were carried out with a bidirectional load using lowering jacks. As a result of the tests, it was found that the resistance of the soil both along the side surface and along the lower end. The resistance along the lower end is on average no more than 10% (when moving 40 mm) of the resistance along the side surface, has a large spread and may not be taken into account in the margin of reliability when calculating. It is also found that the soil deformation modulus determined by reverse calculations based on the results of pile testing is 2...3 times higher than the values determined during standard soil tests, and the soil shear resistance calculated according to SNiP 24.13330.2016 is several times higher than the experimental values. In this regard, it is proposed to determine it taking into account the Coulomb-Mohr dependence, taking into account the over-compaction of the soil.