Pengaruh variasi diameter terhadap kapasitas dukung dan penurunan fondasi pada tanah pasir (studi kasus: gedung rumah susun di Yogyakarta)

Abstract

The foundation is a critical structural component that supports and transmits loads to the underlying soil. In the construction of the Apartment Building in Yogyakarta, the existing foundation type is a bored pile with a 0.6 m diameter and 12 m depth. This study re-plans the foundation using bored piles to analyze the impact of diameter variations on bearing capacity and settlement. The analysis involves three diameter variations—0.45 m, 0.5 m, and 0.6 m—while maintaining a pile depth of 12 m. Standard Penetration Test (SPT) data is used for calculations. Using the Poulos & Davis method, the group pile bearing capacities for diameters of 0.45 m, 0.5 m, and 0.6 m are 3.214,506 kN, 4.033,615 kN, dan 4.803,383 kN, respectively. Meanwhile, the Meyerhof method yields bearing capacities of 3,588.638 kN, 4,286.948 kN, and 4,533.659 kN. Results indicate that larger diameters increase bearing capacity. Settlement analysis shows values of 1.397 cm, 1.246 cm, and 0.547 cm for diameters of 0.45 m, 0.5 m, and 0.6 m, respectively, using both methods. Compared to the initial design, the bearing capacity for a 0.45 m diameter decreases by 2%–12,2%, while diameters of 0.5 m and 0.6 m show increases of 17.1%–31,2%. Settlement increases range from 0%–155% but remain within permissible limits. The findings highlight the significant influence of diameter on both the bearing capacity and settlement of bored pile foundations.