Analysis of soil-structure interaction using 2D/3D FEM calculations in geotechnical design

Abstract

Geotechnical design is a complex, interdisciplinary field involving soil science, mechanics, and rheology. This article presents a comprehensive solution for geotechnical design using digital data from various programs, focusing on Ultimate Limit State (ULS) and Serviceability Limit State (SLS) analysis for a storage hall foundation in challenging geotechnical conditions in eastern Germany. The study utilizes the groundwater conditions and layer layout from the Leapfrog software to create a spatial computational model of the subsoil using Plaxis 3D FEM based on nearly 400 virtual boreholes. Data on hall geometry and load combinations were stored in digital IFC format and tabular data in Excel files respectively. The analysis involved both analytical and FEM 3D/2D methods. In the analytical method, all digital information was collected into one Excel file database for further calculations. Once the consistent digital project database was collected, the same data was implemented into the Plaxis 3D program for FEM numerical calculations. The hall’s foundation solution used footings supported by drilled piles. Soil layer parameters were calibrated based on static pile tests during design calculations. Due to part of the hall being located in a high embankment area (about 5 meters high), consolidation analysis of cohesive soils in the area was considered. The impact of consolidation was factored into negative skin friction in the ULS pile design process. Pile geometry was tailored to existing soil conditions and weak bearing soil thickness. The final foundation geometry and pile lengths were designed to meet SLS conditions set by the structural designer and to address uneven building settlement.