Bored Pile Foundation Performance: Theoretical and PLAXIS 2D Numerical Analysis of At-Ta'awun Tower

Abstract

The soft soil condition beneath the At-Ta'awun Tower building of Universitas Muhammadiyah Surabaya requires a careful foundation evaluation that guarantees safety against axial and lateral loads as well as seismic-induced deformation. This study analyzes the axial capacity, lateral capacity, and deformation of bored pile foundations using static theoretical methods and PLAXIS 2D numerical analysis, and compares the results of both approaches. A quantitative case-study design was applied to the 21-story At-Ta'awun Tower, using secondary data comprising Standard Penetration Test (SPT) results, structural drawings, and structural data. Static axial and lateral capacities were estimated using Meyerhof, Decourt, Reese–Wright, and Broms formulations, while nonlinear finite-element analysis was performed in PLAXIS 2D using the Hardening Soil model. Results show that the static methods produced axial capacities that satisfy the upper-structure load demand, with the Meyerhof method giving the largest capacity. The PLAXIS 2D analysis indicated that an eight-pile group configuration satisfies both the axial capacity and allowable settlement criteria. Compared with the static methods, PLAXIS 2D produced a higher axial capacity, with an average deviation of 139.85%, and a smaller settlement, with an average deviation of -2.25%. For lateral capacity, the Broms method produced larger values than PLAXIS 2D, with an average deviation of 97.1%, while lateral deflection from the Broms method was smaller, with an average deviation of -75.2%. These differences are attributed to the ability of PLAXIS 2D to model soil-structure interaction, stress distribution, deformation, and soil nonlinearity in greater detail. Because the Hardening Soil parameters were derived from empirical SPT correlations without independent laboratory verification and the pile group was idealized under a two-dimensional plane-strain condition, the eight-pile, Hardening-Soil-based configuration is recommended as a conservative design-verification reference for similarly soft soil conditions rather than a generalized result. Further research is recommended to validate the results against field load-test data and three-dimensional modeling.