ANALYSIS OF LIQUEFACTION POTENTIAL ALONG THE JAKARTA MRT THAMRIN-MONUMEN NASIONAL BASED ON STANDARD PENETRATION TEST

• Main Author: Rama Koento Wibisono N.P., R.
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/78875
• Institution: Institut Teknologi Bandung

The Jakarta Mass Rapid Transit (MRT) Thamrin-Monument National Line is an underground tunnel route constructed to address the challenges of high mobility while facing surface space constraints in the capital city. Rail-based transportation within the tunnel also combines comfort and safety, with the advantage of being resistant to earthquake-induced damage. However, there is a case of the Daikai Tunnel collapse due to an earthquake in the history of tunnel construction. This event was followed by liquefaction because it occurred in Quaternary deposits, which consist of loose, unconsolidated, and unstructured sand. Therefore, an analysis is necessary to determine the potential for liquefaction on the Jakarta MRT Thamrin-National Monument Line. The analysis of liquefaction potential is carried out using the Standard Penetration Test (SPT) method. The analysis includes soil classification, the calculation of liquefaction safety factor (FSL), liquefaction potential index (LPI), liquefaction probability (PL), lateral spread index (LDI), and surface settlement value. The analysis was conducted at 18 borehole points on the Jakarta MRT ThamrinNational Monument Line, with varying depths ranging from 29.95 to 49.95 meters. There are two soil types, categorized into eight groups based on their N-SPT values: very soft to soft clay/silt (N-SPT <4), very soft to moderately stiff clay/silt (N-SPT 1-9), stiff clay/silt (N-SPT 10-19), and very stiff to hard clay/silt (N-SPT 20-40), as well as very loose to loose sand (N-SPT 1-9), moderately dense sand (NSPT 10-19), moderately dense to dense sand (N-SPT 20-40), and very dense sand (N-SPT > 40). The FSL values at the 18 borehole points under earthquake scenarios of 7.5 and 8.8 Mw show that only 11 borehole points have the potential for liquefaction because they have safety factors less than 1. Based on the calculated LPI values from these 11 borehole points, the Thamrin MRT Line falls into the low to very high category, while the National Monument MRT Line has a very low LPI value of 0. The PL value on the Thamrin MRT Line ranges from 0 to 100%, whereas it is 0% on the Monument National MRT Line. The largest LDI and surface settlement values, with values of 963.27 and 34.39 cm, respectively, are found on the Thamrin MRT Line. Geotechnical engineering techniques, specifically vibro compaction and dewatering, can serve as viable solutions to augment soil strength in the face of potential liquefaction. These methods entail soil compaction and reduction of pore pressure.