Analysis of the influence of anchor piles on test results

Abstract

The paper considers the main problems of design and calculation of deep foundations of high-rise buildings in the form of piles-barrettes. The results and methodology of field tests of barrette piles for the foundation of a 56-storey residential building in Moscow are presented. The characteristics of engineering-geological conditions of the future construction site and design solutions for pilot tests are presented. Given a large cross-section of the barrette, which involves a significant amount of pile-type soil mass with the formation of a complex stress-strain state, to obtain reliable results and verification of the calculated model is recommended to perform numerical tests in full compliance with the field experiment, taking into account the anchored piles. The paper describes the method and the results of the numerical calculation of the load-carrying capacity of a barrette taking into consideration the modeling of an anchoring system in the Midas GTS NX program complex by the finite-element method and shows the basic possibility of using the program complex and the described method for practical purposes with an admissible accuracy. The paper contains diagrams of vertical displacements of a barrette head as a function of the applied load in full-scale tests and a general evaluation of the carrying capacity of a barrette pile obtained by numerical solutions. It is found that by taking into account the anchoring system (beams and piles) in the numerical simulation, the calculation results obtained are the most accurate to the field tests in describing the behavior of the pile under load in comparison with the calculation of a single barrette pile. In spite of the fact that the barrette bottom is embedded into the rocky soils, the barrette piles are referred to the hanging piles according to the interaction conditions with the soil due to the significant load transfer along the lateral surface.