Geotechnical Engineering Journal of the SEAGS & AGSSEA ISSN 0046-5828
Vol. 45 No.3 September 2014
Performance of Rail Embankments Constructed with Coal Ash as a Structural Fill Material: Centrifuge Study
B.V.S. Viswanadham and V.K. Mathur
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. Geogrid reinforcement layers in a reinforced coal ash embankment with 2V:1H slope were observed to experience straining after applying a bearing pressure of 250 kPa in the top-half zone and indicating a need to provide high strength layers in top-half zone. Further, results of stability analysis of soil confined coal ash embankment models constructed with coal ash as a fill material were found to corroborate well with physically observed centrifuge test results.
KEYWORDS: Performance, Rail Embankments, Coal Ash, Fill Material, Centrifuge Study
