Use Of Geosynthetics In Mitigating The Effects Of Mud-Pumping: A Railway Perspective
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In Australia, where the major network of railways traverses along the coastal regions, millions of dollars are spent on track maintenance annually to mitigate track differential settlement. One of the recurring problems faced with ballasted tracks on estuarine soils is mud pumping. Mud pumping is a complex phenomenon involving the migration of fine soft subgrade particles into the coarser ballast/sub-ballast layer. The problem has been widely reported and is of interest among the railway engineers over the last couple of decades. The migration of fines causes excessive settlements and track degradation leading to track instability, thereby incurring excessive maintenance costs. The primary objective of this paper is to assess the existing remediation measures for mud pumping reported. The current mitigation techniques range from the in-situ mixing of additives to the use of geosynthetics to separate the layers in a track structure. On the other hand, the use of geosynthetics has proven to act as a separator between the track layers; their effectiveness is highly dependent on the type of subgrade soil. The comprehensive study reveals the probable causes of mud pumping and a better understanding of the phenomenon.