Suitability analysis of vertically installed scoria gravel drains for enhancing consolidation performance of clayey ground

Abstract

In alleviating challenges associated to long-lasting consolidation of clay, highly permeable materials such as sand and crushed aggregate are used as drain. Despite the fact that granular vertical drains are effective in shortening the prolonged consolidation period of clay, limited information exist regarding applicability of scoria gravel as vertical drain that no concisely documented information is observed in literatures. This study hence aimed at evaluating suitability of scoria gravel as vertical drain in perpetuating consolidation process of soft clay under road embankment. Finite element-based simulation was used to model the drains. To incorporate the effect of gradual load increment on consolidation rate, staged construction approach was employed. Various dimensions of scoria vertical drain (SVD) have been considered to investigate the effect of dimension parameters. Besides, comparison has been made between performances of SVD and crushed aggregate drains (CAD) in impacting the consolidation process. The numerical analysis result revealed that provision of group of SVD considerably accelerated consolidation rate. With increase in drain diameter, the consolidation rate goes increasing whereas it is inversely related to increase in drain spacing. For SVD installed at spacing of 2 m, diameter of 0.4 m and length of 8 m any arbitrary settlement magnitude is achieved 25 days earlier than the case without drain. No considerable difference was witnessed in performance of the square and triangular installation patterns though the consolidation rate remains slightly faster in the case of triangular installation. In speeding up consolidation rate, SVD was observed to perform slightly better than the CAD.