| Summary: | Generation of mud pumping is commonly triggered by a combination of three main factors such as excess fines, excess water, and cyclic loading. Excess fines particle is generated from depositing mechanisms (i.e., dust, waste material and ballast breakage) and fluidisation or internal erosion mechanism (i.e., subgrade degradation). Mud pumping phenomenon that is associated with ballast fouling has been widely discussed and is of interest among the railway engineers and researchers. However, subgrade degradation or fluidisation of subgrade layer induced mud pumping mechanism gained less attention from the researchers due to complexity of subgrade soil behavior. Various methods applicable in railway track’s subgrade degradation assessment based on destructive and nondestructive test were comprehensively reviewed in this research paper. The assessment on subgrade mud pumping is based on migration of the subgrade fine mechanism including in-situ excavation test, particle size distribution test, ground penetrating radar (GPR) and physical modelling test. This paper summarizes the advantages and weaknesses of various assessment methods of subgrade degradation induced mud pumping and clarifies most effective method for repair and maintenance of railway track. © 2022 by authors, all rights reserved.
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