2021 2.3 Design Concept: Performance Through Stabilization The engineering approach adopted in this project was based on improving material efficiency rather than adding mass. Using established unpaved road design methodologies previously applied at the site, including Giroud–Han-(2004) based thickness design and structural evaluation tools, the reinforced configuration was developed to reduce the thickness of high-quality rock layers while maintaining trafficability requirements. This shifts from a thickness-driven design philosophy to a stabilization-driven solution enabled: • Use of locally available itabirite materials • Reduction of imported rock volumes • Faster construction and rehabilitation cycles • Lower hauling demand and associated fuel consumption In practical terms, the intervention transformed the haul road from a structure that required continual material replacement into one capable of maintaining serviceability under production loading and seasonal rainfall conditions. 3. CASE STUDY DESCRIPTION 3.1 Operational Context The case study was conducted at an operating iron ore mine characterized by high production volumes and well-defined seasonal climatic conditions, with hot and humid summers marked by intense rainfall and dry winters. The mine relies on a network of unpaved internal haul roads to transport ore from the pit to the primary crusher. These roads are trafficked by haul trucks (Komatsu 830E-AC), with gross vehicle weights exceeding 400 tons and operating frequencies ranging between 650 and 800 cycles per day under normal production conditions. Given the scale of operations, haul road reliability directly influences crusher feed continuity, equipment utilization, and daily production targets. 3.2 Performance Challenges Prior to Reinforcement Before implementation of the reinforced solution, the haul roads were constructed using conventional mine practices based on locally sourced materials placed in thick granular layers without controlled compaction. A typical section consisted of: • 1.0 m of coarse rock fragments forming the working platform • 0.7 m of itabirite-based sub-base material • 0.3 m of crushed aggregate used as a wearing surface These roads were particularly vulnerable during the rainy season (October–May), when monthly precipitation could exceed 200 mm, leading to rapid degradation of the running surface, deep rutting, and traffic instability. Operational monitoring indicated that rainfall events significantly affected haulage efficiency, reducing the average velocity of trips and impacting production continuity.
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