Laboratory study on the spacing effect of vertical drains on the consolidation characteristics of clay

Abstract

Sand drains are extensively utilized to fasten the consolidation rate, especially in soft clay deposits. However, due to the scarcity of sand, it should be substituted with some cost-effective material. In view of this, in the current investigation, along with sand, waste materials like rice husk ash, coir pith, fly ash, and quarry dust were used as drain materials. The consolidation test was performed using Kuttanad clay, filled in a mould of 15 cm diameter and 10 cm height, allowing single drainage. A triangular pattern of three drain system was used in the study. A parametric study on the effect of the spacing of the drain on consolidation characteristics was investigated by varying the spacing/diameter ratio (s/d ratio). It was observed that the consolidation rate is more for coir pith and quarry dust drains compared to rice husk ash and fly ash drain used in the study. The consolidation rate reduces with the increase in the spacing of the drain. For achieving a particular consolidation rate, the required drain spacing has to be known. Correlations were developed to predict the spacing between the drains for attaining a particular coefficient of consolidation.