SOIL BEARING CAPACITY ANALYSIS TO DETERMINE PILE FOUNDATION DESIGN ON ALLUVIAL SOILS IN SEMARANG CITY, INDONESIA

Abstract

Semarang City is one of the largest cities in Indonesia and has experienced land subsidence for decades, with the second-fastest rate in the world at 20–30 mm per year. This issue can significantly affect the stability of building structures. One infrastructure project that requires attention due to this condition is the revitalization of Baiturrahman Mosque, located in Semarang City. Designing an appropriate foundation structure based on geological and geotechnical conditions is crucial. The foundation type must be determined according to localized soil conditions by calculating the bearing capacity using Standard Penetration Test (SPT) data, core drilling, and laboratory tests. Based on soil consistency, the pile foundation tips should be embedded at a depth of 20–30 meters at four locations within the study area. The Meyerhof method is used to analyze the required number of driven pile foundations, while the Poulos method is applied for bored-pile foundations. The analysis recommends 24 driven piles of 600 mm diameter at BM-1, 48 driven piles of 600 mm diameter at BM-2, 15 bored piles of 600 mm diameter at BM-3, and 15 bored piles of 600 mm diameter at BM-4. For the geological and geotechnical conditions of the study area, the Meyerhof equation is the most suitable method for determining the number of driven piles, while the Poulos equation provides a more accurate estimation for bored piles.