Pengaruh likuefaksi terhadap daya dukung fondasi bored pile pada Jembatan Bantul-Kulon Progo P10-177 dan P13-234

Abstract The Kabanaran Bridge is a 2-km structure spanning the Progo River and connecting Bantul and Kulon Progo regencies. Based on the Yogyakarta Liquefaction Zone map published by the Geological Agency in 2019, the bridge site falls within a high liquefaction-vulnerability zone; therefore, an evaluation of foundation bearing capacity considering liquefaction effects was conducted. Bearing capacity was analyzed using Meyerhof (1963) and Reese & O’Neill (1989) methods, while Pile Driving Analyzer (PDA) test results were used to compare design predictions with in-situ field capacity. Liquefaction potential was assessed using the Safety Factor approach and the Idriss & Boulanger (2008) procedure. Results indicate that a subsurface layer is susceptible to liquefaction for an earthquake of M = 7.5, prompting detailed evaluations at piles P10 and P13; the analyses show reductions in bearing capacity ranging approximately 17–91% at P10 and 20–91% at P13. Despite these substantial reductions, both foundations continue to satisfy safety requirements (P < Qg), and liquefaction effects at depths greater than 20 m can be disregarded because they do not influence surface behavior.