A “geotechnical analysis” of haul roads in a mining site is defined as the comprehensive analysis of the subgrade and structural components to determine their suitability to carry extra-heavy load of trucks over an extended period. On the other hand, “wear course” denotes the top most layer of the pavement which contacts with the truck wheels in order to provide friction, draining and abrasion resistance. “Rolling Resistance” is defined as the drag force produced due to contact between the wheel and pavement surface which must be overcome during movement of vehicle.
Geotechnical analysis requires thorough investigation of the location in question, and this starts by taking samples of subgrade soils at the site and determining both the CBR and elasticity levels of the in-situ soil. Recent methodologies include the use of mechanistic empirical analysis to determine compressive strains in soils with different layer depths. This is aimed at detecting weak areas where engineers can determine how thick a base should be, or even where geosynthetics should be used.
The function will then be considered after completing the structural aspect, but here the wearing course is very important. Selection of wearing course material involves a study on particle size distribution and Atterberg limits of the aggregates used. A good wearing course material has to be the best in achieving the compromise between the plastic property and coarseness of the aggregate which should not fail under abrasive stress. Specification of wearing course leads to satisfactory results of repelling water and providing enough friction irrespective of whether it is wet or dry weather.
The quality of this course is responsible for rolling resistance which, in its turn, has a major impact on the consumption of fuel and economic aspects of hauling in general. High rolling resistance takes place when the surface is too soft or loosely compacted; it makes trucks’ wheels sink into this surface and makes trucks continuously struggle against their own tracks. When a proper wearing course is selected so that it becomes possible to compact it and get very rigid surface, tire sinkage becomes minimal.
Similarly, a properly defined wearing course helps avoid massive vehicle damages. Pavements made from large-sized stones and improperly compacted materials develop potholes, ruts, and loose stone aggregates quickly (Thompson & Visser, 2000). Such pavement deficiencies generate high shock forces in the truck’s suspension system and driveline, thus making the metal parts vulnerable to wear-and-tear. Loose stones may cause extra wear of tires and punctures of their tires. Proper regulation of particle size distribution and compaction helps to secure the smoothness and longevity of extremely expensive mining machinery.
In summary, designing an effective haul road requires a strong synergy of skills in geotechnical engineering and materials science. Performing a proper geotechnical investigation ensures the pavement structure’s stability in terms of huge stresses caused by loaded hauling trucks (Gouda et al., 2024). At the same time, defining a tightly compacted and well-graded wearing course provides for the proper pavement surface that is trafficable and lacks any major problems. In this case, rolling resistance and truck damage are minimized.
References
Baek, J., & Choi, Y. (2017). A New Method for Haul Road Design in Open-Pit Mines to Support Efficient Truck Haulage Operations. Applied Sciences, 7, 747. https://doi.org/10.3390/app7070747
Gouda, J., Rami Reddy, D. S., Srinivasan, V., & Butle, V. (2024). Comprehensive Review of Haul Road Design Methods: a Comparative Approach. Archives of Mining Sciences, 529–554. https://doi.org/10.24425/ams.2024.151449
Thompson, R. J., & Visser, A. T. (2000). Selection parameters for mine haul road wearing course materials. International Journal of Surface Mining, Reclamation and Environment, 14, 1–17. https://doi.org/10.1080/13895260008953294
