Impact of residual mining subsidence on road infrastructure in Merriespruit, Free State Province, South Africa

Abstract

In South Africa mining has left many underground goafs that persistently cause mining subsidence, even after many years. This phenomenon still poses a real challenge in various mining towns. The purpose of this study was to evaluate the ongoing subsidence affecting the road infrastructure in Merriespruit, Virginia, Free State province, South Africa. In terms of the actual research, a high accuracy Real Time Kinematic Global Positioning System (RTK-GPS) tool was used to carry out surveys on several streets in Merriespruit. The historical road design plans from the Municipality of Mathjabeng were used to assist in explaining the changes that occurred particularly to the ground or road surface. The outcome of the study revealed that various streets have experienced different levels of subsidence. Some streets have shown visible damage, while others have depicted uneven deformation. Few streets are also showing signs of persistent and gradual sinking. Additionally, streets closer to the Merriespruit #3 shaft and those constructed many years ago appeared to be the most affected with highest changes in elevation recorded. Finally, the study showed evidence of ongoing subsidence that is affecting the quality of road and water drainage networks and the safety of residences. Regular monitoring using tools such as Interferometric Synthetic Aperture Radar (InSAR), RTK-GPS, and Light Detection and Ranging (LiDAR) is therefore recommended. Most importantly, the findings stemming from this research study provides essential information for the local municipality for mitigation plans against mining subsidence.