Performance of Rail Embankments Constructed with Coal Ash as a Structural Fill Material: Centrifuge Study

Abstract

The objective of the present study is to understand the stability and deformation behavior of rail embankments constructed with coal ash as a structural fill material through centrifuge model tests. Two types of railway embankments were modeled: 1) Clay confined coal ash embankment with 1V:2H slope of 11 m height and 2) Geogrid reinforced coal ash embankment with 2V:1H slope of 4 m height using a large beam centrifuge facility available at IIT Bombay. Considering the nature of railway embankments and possibility of buildingup of ground water table due to rainfall, a seepage tank simulator was used to induce seepage into the rail embankment during centrifuge tests. After establishing steady-state seepage conditions, the crest of the embankment was subjected to an incremental static loading pressure distributed through a rigid strip footing up to 700 kPa or failure, whichever occurred first. Additionally, an option of provision of drainage at the mid-height of the railway embankment was also explored for clay-confined coal ash embankments. Based on the analysis and interpretation of centrifuge model test results, for a soil confined coal ash embankment with 1V:2H slope with a confinement layer of 1.5 m thickness in the top-half height and berms in the bottom-half zone was observed to sustain an ultimate load bearing pressure of 400 kPa...