OPTIMIZATION OF TUNNEL DESIGN: THE IMPACT OF RMR CLASSIFICATION ON TIME EFFICIENCY

АУТОР(И) / AUTHOR(S): Stefani Gjorgjevska , Zlatko Zafirovski

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DOI: 10.46793/GEOAG25.155G

САЖЕТАК / ABSTRACT:

Tunnel construction is crucial for developing transportation infrastructure in regions with complex geological conditions, such as Macedonia, where mountainous terrains, variable rock masses, and high groundwater inflow often cause delays and cost increases of 20-30%. This study analyses how the Rock Mass Rating (RMR) classification impacts time efficiency in tunnel design and construction, aiming to identify optimal strategies for reducing time and risks in local projects. The methodology involves quantitative analysis of 341 tunnel segments with RMR values from 0 to 80, using field data, statistical methods, and comparisons with international projects. Results show that low RMR values enable rapid excavation (2.35-5.71 m/day) but require intensive stabilization (20-50 days) with measures like rock bolts, pipe umbrellas, and shotcrete, while high RMR values  reduce stabilization time to 5-10 days. Technologies with smaller excavation steps (0.75 m) optimize time by 30-40%, particularly for 55-60 m² sections. Integrating RMR into planning reduces collapse risks by 15-20%, costs by 20-30%, and ensures economical and safe construction.

КЉУЧНЕ РЕЧИ / KEYWORDS:

Geological conditions, optimization, RMR , tunnel construction, time efficiency

ПРОЈЕКАТ / ACKNOWLEDGEMENT:

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