On the Identification of Critical State Lines for Sands

New methods of geotechnical design in sands are often based on a state parameter type of approach, requiring the in situ state of the soil to be quantified relative to its critical state line. One difficulty in the application of these methods is then the correct identification of the location of this line, particularly at lower stress levels where sands strain soften and strains tend to localize within the sample. This paper examines the shearing behavior of two sands of diverse mineralogy by means of triaxial testing. The approach adopted has been to use existing techniques and apparatus that might reasonably be implemented in general practice. Recommendations are made as to the type of apparatus and test that should be used, and the corrections necessary to the data in order to identify as accurately as possible the critical states.