Engineering geological characteristics in planned tunnel B route of the Yogyakarta-Bawen toll road

This paper presents a comprehensive engineering geological assessment of the planned Tunnel B route within the Yogyakarta-Bawen Toll Road project, a critical national infrastructure undertaking connecting Central Java and the Special Region of Yogyakarta. With Tunnel B spanning 510 meters, this study aimed to inform the project’s planning and implementation processes. The research encompassed geological surveys, core drilling assessments, testing of rock and soil properties, and analysis of geoelectric survey data. The findings delineate two primary geological units: completely weathered andesite and completely weathered breccia tuff. Groundwater was detected at depths ranging from 13 to 40 meters above the tunnel’s intended elevation. The resistivity of rocks and soils along the tunnel route ranged from 5 to 750 Ωm, leading to the identification of six zones (A, B, C1, C2, C3, D, E, and F) with distinct geological engineering characteristics. This research offers pivotal insights essential for the effective planning and execution of the Yogyakarta-Bawen Toll Road project. It provides crucial information regarding the geological attributes and expected tunnel behavior, ensuring the project’s success and long-term sustainability.