Evaluasi kapasitas aksial tekan tiang bor berdasarkan data SPT dan SLT : studi kasus Gedung Rumah Sakit Klaten

Abstract

Bored pile foundations are frequently used in multi-story and infrastructure projects due to their ability to transfer large loads to deeper soil layers with higher bearing capacity. In this study, the axial bearing capacity of bored pile foundations in the construction project of Klaten General Hospital was evaluated using empirical methods based on Standard Penetration Test (SPT) data and verified through a field test using Static Loading Test (SLT). The empirical approaches applied were the Kulhawy (1984) and Reese-Wright (1977) methods, which utilize N SPT values to estimate skin friction and end bearing capacity. The pile under evaluation had a diameter of 0.8 meters and a depth of 26 meters, with a design load of 200 tons. SLT was performed with a 500-ton hydraulic jack and interpreted using the Mazurkiewicz graphical method. The ultimate bearing capacity (Qult) results obtained from Kulhawy and Reese-Wright were 565.577 tons and 570.588 tons, respectively, while the result from SLT interpretation was 590 tons. The percentage differences were -4.14% for Kulhawy and -3.3% for Reese-Wright compared to SLT, indicating that both methods provided conservative and close estimations to the actual field data. Based on the comparison, the Reese-Wright method produced results that more closely aligned with the SLT outcome. This study shows that integrating empirical SPT-based calculations with SLT verification provides a reliable approach for evaluating bored pile performance in local soil conditions, especially in clay-dominated strata like those found at the project site.