Inflection point method to estimate c(h) from radial consolidation tests with peripheral drain

Horizontal coefficient of consolidation ch is a key parameter in the design of vertical drains and the following consolidation analysis of a soil layer. There are graphical and non-graphical methods available to estimate ch from laboratory radial consolidation tests with a central drain. Currently, the consolidation tests with peripheral drains have to be analysed through a curve fitting method for determining ch. In this technical note, a non-graphical inflection point method is proposed for determining ch for an oedometer test with peripheral drainage, based on the characteristic feature observed when the gradient of the theoretical Ur –log Tr relationship was plotted against Tr. The proposed method is validated through a series of consolidation tests on two reconstituted dredged clay specimens, tested in an oedometer subjected to radial drainage with peripheral drains. The consolidation settlements predicted from the proposed method, for the two different clays, were in excellent agreement with those measured in the oedometer. The proposed method will be a very valuable tool in the analysis of radial consolidation data when the drains are peripheral