Accurate Analysis of Stand-up Time Rock Collapse When Inlet Tunnel Excavation is Carried out in there are Cracked and Broken Rock Formations and a Poorly Silty-clay Soil Profile

Munirwansyah*, Reza P Munirwan and Surya Dharma

The condition of the rock formation and the poor stability of the type of soil mass (problematic soil) in the tunnel excavation route greatly influence the achievement of the collapse (stand-up time) that will occur. The thickness of the overburden pressure above the tunnel opening is often difficult to meet, so in the inlet zone as well as in the out-let zone, slope collapse often occurs and disrupts the work implementation schedule. On the slope of the inlet excavation location, there are also silt formations with outcroppings. Rocks from small to large sizes and there are even rock masses that are cracked so that the quality or strength of the rock is unstable when exposed to the equipment used when tunnel excavation work is carried out. This research method was carried out using an approach that corresponds to the Rock Quality Designation (RQD) value with the Rock Mass Rating (RMR) value which will provide a classification of rock classes and excavation methods. The data used in this research is rock data at the tunnel inlet of the Rukoh Dam Steering Building. From the RQD and RMR data and soil physical properties obtained in this research, analysis was carried out using the empirical approach introduced by Bieniawski. The results obtained from the in-situ test drilling work, the results of which were stored in the core box at the tunnel inlet, obtained an RQD value equal to 32.5% and an RMR value equal to 15. The RMR value shows that the rock at the tunnel inlet falls into the very category poor. With a tunnel opening as wide as 6.60 M, the stand-up time at the tunnel in-let is less than 30 minutes. 

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Published on: Jul 31, 2024 Pages: 54-60

Full Text PDF Full Text HTML DOI: 10.17352/2455-488X.000084
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