Constant rate of strain consolidation with radial drainage

This paper describes a method of determining the consolidation characteristics of soft Bangkok clay under the radial drainage condition by using a newly developed constant rate of strain (CRS) consolidometer. A new formulation for this type of test was proposed. A series of constant rate-of-strain consolidation tests were compared to the results of oedometer tests. The pore water pressure distribution across the specimen in the CRS tests was estimated from measurements made at two locations. The results agreed well with the theoretical solution. A simple method of estimating the preconsolidation pressure by means of the pore water pressure ratio is also proposed. Because the tests conducted at different strain rates indicate that apparent preconsolidation pressure increases with strain rate, it is believed that secondary compression occurred during primary consolidation for this clay. The consolidation characteristics, including coefficient of consolidation and coefficient of permeability, in the vertical and horizontal directions were also compared.