Interaction between a long pile and multi-layer underlying soils

Introduction. The majority of construction sites feature complex geotechnical conditions, as they have alternating soil layers, including loose soils. A pile foundation is the principal type of foundations constructed on these sites. This article encompasses a problem statement and a solution to the problem of interaction between a long pile and multilayer underlying soils. Materials and methods. The problem is explored in linear and nonlinear settings. The S.P. Timoshenko elastoplastic model is analyzed to describe nonlinear shear deformations. Analytical and numerical methods are employed to present the solution. The results of the analytical solution are compared with the results of the elastic problem obtained using the Plaxis 3D software package. Results. An equation designated for determining the reduced shear modulus of the multilayer soil mass is obtained. Analytical solutions are supported by the graphical solution obtained using Mathcad software. Numerical solutions are obtained using the Plaxis 3D software package. The diagrams describing the dependence of the settlement of the pile, that passes through alternating soil layers, on the load are provided. The diagrams, describing the dependence between the force, applied to the pile toe, and the pile radius in case of a variable load applied to the pile head and variable pile length are provided. Conclusions. The resulting dependence, needed to determine the reduced shear modulus of the multi-layer soil mass, demonstrates good convergence with numerical methods in the elastic setting. These solutions can be used to pre-determine the displacement of a long pile surrounded with the underlying multi-layer soil mass. The selection of an optimal correlation between the pile length and the pile diameter allows for the most effective use of the bearing capacity of the pile.