INNOVATIVE TECHNOLOGIES FOR DEEP FOUNDATION (SHELL PILES) ANALYSIS USING THE BOUNDARY ELEMENT METHOD (BEM)

Abstract

The paper addresses the solution of a current spatial contact problem in the behavior of deep foundations, specifically shell piles used for transferring significant loads to soil foundations, utilizing the numerical Boundary Element Method (BEM). One of the main tasks in construction design is assessing the technical and economic feasibility of using specific foundation types, taking into account the particular natural conditions of the construction site. Notably, the estimated cost of the underground part of a building in complex engineering and geological conditions constitutes 40-45% of the total cost.

To determine the optimal solution, variant design is applied, based on principles of cost-efficiency, reliability, construction speed, maximum utilization of the bearing capacity of soils and foundations, and the use of modern advancements in soil mechanics and computer technologies.

Currently, mathematical modeling is one of the key and most economical tools for theoretical and applied research in foundation engineering. Settlement prediction of foundation soils remains one of the most complex challenges in soil mechanics. A significant potential for gaining an accurate picture of the stress-strain state of the soil foundation lies in the elastic-plastic soil model under load, which is used in this study.

Since the overall assessment of soil mass stability is of primary importance in foundation design, reliability and economic calculations of foundation structures determine the success of the construction as a whole. Modern mathematical models for describing soil behavior are systems of partial differential equations, which are too complex for analytical solutions. The behavior of a shell pile under load—a problem in geomechanics—can be solved using numerical methods, one of which is the Boundary Element Method (BEM).

The input parameters for the numerical simulation program include values that characterize the physical and mechanical properties of the soil, and describe the geometry and topology of the design scheme.

The obtained research results provide answers to a wide range of issues addressed in the design of shell piles. The BEM-based software allows for the determination of coefficients of the BEM influence matrix (the soil compliance matrix). To obtain these, the boundary of the contact area between the foundation structure and the soil is discretized using linear boundary elements, the weighted average soil properties are defined, and the required dimensions of the foundation structure are established.

The numerical approach is illustrated through stress-strain state calculations of the pile at each loading step, considering the dilatancy properties of the soil using an elastic-plastic soil model. A comparative analysis of the bearing capacity of shell piles based on calculations and current regulations is provided.