2010 Volume 66 Issue 3 Pages 660-670
It is well known that effective pressure and strain relation is strongly dependent on the strain rate and its dependency is very important to predict settlement caused by consolidation including secondary con-solidation. Many researchers have proposed strain rate dependent models, including so called Isotach model, whose compression curves on given strain rates are parallel in ε-log p’ relation and a parameter of strain rate dependency is expressed as the function of the strain rate. To examine the strain rate dependency of cohesive soils on compression curves under very slow strain rates, a Slow Constant Rate of Strain (SCRS) oedometer was developed to attain the minimum strain rate of 3.8 × 10-10 s-1. SCRS test was carried out on five different cohesive soils of intact as well as reconstituted samples. It is found that although compression curves of all clays strongly depend on the strain rate, the Isotach model can be applied to only Osaka clay.