On the Measurement of Critical State Parameters of Dense Granular Soils
Existing test methods for measuring the critical state parameters of granular soils are reviewed and critically evaluated. It is concluded that, in triaxial testing of dense sand, significant nonhomogeneous deformation will develop prior to approaching a critical state. Hence, the critical state parameters so measured are questionable. A new test method, referred to as post-failure undrained testing, is presented. The proposed method is simple, but can bring a dense granular sand to a critical state without development of noticeable nonhomogeneous deformation. The critical state parameters so measured with dense specimens agree well with those measured with loose specimens. This is consistent with the postulate that the critical state surface is unique.