Bearing capacity of frame-gantry pile foundations

The object of the study is frame-gantry pile foundations embedded in the soil base. To improve the strength of weak soil base, various methods of reinforcement are used, including the foundation constructions in the form of wedge-shaped piles. The paper deals with laboratory studies of the soil base during the installation of small-scale wedge-shaped piles at different angle. The process of soil shearing under the influence of the loads is registered by deformation control benchmarks arranged in the form of a square grid. The interaction between the soil and the frame-gantry foundations appears in a change of the physical and mechanical characteristics in the near pile area. The tests revealed that when piles are installed at the angle of 30° the bearing capacity of the foundation increased. The average density in the fixed active zone of the soil area increased by 12 %, and the average porosity coefficient decreased by 20 %. The deformation modulus changed by 1.8–2.3 times. The angle of internal friction remained virtually unchanged.