Appropriate Method of Determination of Coefficient of Consolidation for Municipal Solid Waste

Abstract

Abstract To predict the rate of settlement of municipal solid waste specimens (MSW), it is essential to estimate the value of the coefficient of consolidation (Cv) using laboratory consolidation test results. Literature suggests that the various empirical curve-fitting methods used for assessing Cv are Casagrande’s logarithm of time fitting method and Taylor’s square root of time fitting method for the same test data. Both methods are derived from the time factor and degree of consolidation (T–U) relationship and corresponding laboratory time–compression (T–δ) relationship. For different types of wastes and loading conditions, the shapes of curves vary considerably, and the validity of these approaches is not established. In all these cases, the estimation of the Cv poses a serious problem. To overcome the above difficulties, the rectangular hyperbola method is used, in this article, to determine the Cv by U–T or t versus δ relationship. Earlier, this method was used for different coefficient of consolidation values of time for completion of different percentages of consolidation. It is found that the calculated values of Cv are found to be more reliable when the time for 60 % of consolidation is taken. The estimated Cv values from the rectangular hyperbola method lie between the existing standard methods of Casagrande’s and Taylor’s. The rectangular hyperbola method is simple and can be used for all shapes of time–compression curves, and the specific advantage of this method is that the initial compression need not be known and is devised to separate the initial, primary, and secondary compression for any load increment.