Restoration of Railway Embankment

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The paper examines the failure and proposed rehabilitation of approximately 100 metres of railway embankment in eastern India after a week of heavy rainfall. The embankment settled near the track, while the cantilever toe wall shifted and soil heaved beyond it.<br /><br />Geotechnical investigations identified soft clay beneath part of the embankment, with an undrained strength of about 15 kPa. The authors attribute the failure to rising groundwater during the rains, which increased the embankment’s weight and caused the soft clay to squeeze and settle. The existing slope had a factor of safety below 1 in the assessed conditions.<br /><br />The proposed repair combines an 800 mm diameter contiguous bored-pile wall at the embankment toe with compaction grouting beneath the embankment to strengthen the soft clay. The design was assessed using slope-stability and structural-analysis software. For the proposed scheme, the reported factors of safety were 1.474 under static loading and 1.1 under seismic loading, meeting the study’s design criteria. Pile stresses and deflection were also assessed, and reinforcement was specified.<br /><br />The case highlights the importance of investigating subsurface conditions when designing railway embankments. It concludes that a contiguous pile wall can help restrain soil movement, while ground improvement can strengthen weak underlying strata.

Keywords

railway embankment

embankment failure

geotechnical investigation

soft clay

groundwater rise

slope stability

compaction grouting

contiguous bored pile wall

factor of safety

ground improvement