Modelling surface infrastructure subject to mining impact

Mining companies have to assess any potential mining impact on surface infrastructure such as pipelines, dams and railways as part of the development application of a proposed mine plan. Very often assessment of simple structures such as buildings can be performed based on established guidelines. However, mining impact on other complex structures such as dams and railway embankments may require the use of numerical models to capture complex structural behaviour. This paper presents two case studies highlighting the use of the state of the art numerical modelling technique to address the potential mining impact on complex surface infrastructure. The first case study is a railway embankment proposed to be undermined by coal seam extraction by a series of longwalls. The change in stress and strain within the embankment was required for stability consideration. The second case study is a concrete arch dam being affected by potential ground movement due to underground coal extraction by the bord and pillar method. The pre- and post-mining safety status of the dam needs to be assessed. The case studies will show how the investigation was carried out, the various assumptions made, and the limitations and uncertainties associated with the numerical modelling. Some interesting results will also be shown in the paper.