Interaction of bored pile foundations with the soil base

Abstract

The method of testing soil with piles makes it possible to determine the bearing capacity of a pile in the soil as accurately as possible. This is explained by the fact that static tests of full-scale piles with indentation loads make it possible to most accurately reproduce the conditions of operation of a pile in the soil under load from superfoundation structures of a building or structure. Static tests of natural piles should be carried out in advance, before the construction of pile foundation structures, because their results are used to decide on the need to make corrective changes to the pile foundation design. However, static tests usually require significant time, which is due to their execution technology. And the main disadvantage of static tests of natural piles is the cost compared to other available approximate methods. The calculated value of the bearing capacity of a bored pile, determined on the basis of engineering calculations, allows only a preliminary and approximate assessment of the pile's performance in interaction with the soils of the construction site. This calculation method is characterized by simplicity of application, but at the same time has limited accuracy, which may affect the final results of the analysis. Computer simulation of the interaction of a bored pile with the soil on the lateral surface and under its sole allows us to approximate the simulation results to the results of a full-scale static test of an experimental pile, provided that the parameters for the selected mathematical model of the soil environment are identified.

The Midas GTS NX software package was used for computer simulation of a full-scale experiment, namely, testing a bored pile with static compression loads. At the same time, volumetric finite elements were used for the soil mass and the pile shaft. The behavior of the soil under load was described by a nonlinear law of deformation of the soil medium with a modified Mohr-Coulomb strength criterion. The study paid attention to the redistribution of longitudinal forces in the pile shaft, the nature of the load transfer to the soil through the lateral surface and under the pile base at all stages of loading.