Piezoprobe test interpretation on soft clay
Abstract
This paper describes and compares different methods to interpret dissipation tests on soft clays by using piezoprobe tests. Emphasis is given to estimate initial pore-water pressure (ui), in situ equilibrium pore-water pressure (u0) and horizontal coefficient of consolidation (ch). In this regard, it is important to interpret precise values for ui and u0 in order to better define dissipation curves and obtain more reliable ch values. Current approaches to estimate ui are visual inspection and a √t method whereas attitudes to evaluate u0 fall into simple-empirical (e.g. 1/t and 1/√t methods) and numerical back analysis. Further ch is commonly evaluated based on methods such as Torstensson, Levadoux and Baligh, and Houlsby and Teh. In this study, these methods are described and they are used for interpreting dissipation tests on clay obtained at an onshore site and five different offshore sites. ch estimated from dissipation tests are compared with corresponding laboratory results.