The impact of haulroad geometric parameters on open pit mine strip ratio

Abstract The aim of the study was to analyze the impact on the strip ratio (SR) through varying haul road geometric parameters in two types of deposits, namely one with a steeper dip and a second one with a more equidimensional horizontal behavior. The SRs and the overall slope angle were compared with a base scenario, where the results show an increase in the SR when: (a) the width of the haul roads was increased; (b) the longitudinal grade of the road was decreased; and (c) switchbacks were added. The increase in the longitudinal grade of 2% was considered the best-case scenario, resulting in 1.08% decrease in the SR for the horizontal deposit and in a 4.15% decrease for the vertical one. It was also noticed that the SR variations are inversely proportional to the overall slope angle variations, illustrating the important role that the geometric design of the haul roads has in the return on capital.摘要 本研究旨在分析两种矿床中，运输道路（haul road）几何参数变化对剥离比（strip ratio）的影响：一种为陡倾矿床，另一种为近水平等轴赋存的矿床。研究将各工况下的剥离比与整体边坡角（overall slope angle）与基准场景（base scenario）的对应参数进行对比，结果显示当出现以下情况时剥离比会升高：(a) 运输道路宽度增加；(b) 道路纵向坡度（longitudinal grade）降低；(c) 增设折返式道路（switchbacks）。而纵向坡度提升2%的工况被认定为最优场景，此时近水平矿床的剥离比降低1.08%，陡倾矿床的剥离比降低4.15%。此外研究还发现，剥离比的变化与整体边坡角的变化呈反比关系，印证了运输道路几何设计对资本回报率（return on capital）的关键作用。