The elastic undrained modulus E_u50 for stiff consolidated clays related to the concept of stress history and normalized soil properties

The paper presents the results of a triaxial test conducted on stiff, consolidated clays. The standard TXCIU procedure (isotropic consolidation and undrained shearing) was applied in the laboratory soil tests. The undrained elastic modulus E_u50 was determined from each test.

The E_u50 values were determined for soil samples cut out from different depths and tested under different confining pressures. There was a significant scatter of values with depth, and no relationships between E_u50 modules or other geotechnical parameters (e.g., c_u) were observed.

This work presents the concept of normalization of E_u50 modulus values using modified normalization SHANSEP (Stress History And Normalized Soil Engineering Properties). This method was first proposed for estimating the value of the undrained shear strength c_u normalizing the parameter relative to the in situ effective vertical stress σ′_vo and loading history (overconsolidation stress σ′_p and overconsolidation ratio OCR) of the soil.

The study demonstrated that the concept of normalization of soil properties can also be used for testing elastic modulus E_u50 of consolidated natural clays and normalized values of geotechnical parameters taking into account the state of stress and load history can be correlated with the value of the overburden pressure.