IIT Gandhinagar  ajanta@iitgn.ac.in  ap@iitgn.ac.in
Soil Testing Lab

Introduction Experimental Setup Data Analysis Results Theory

Consolidated Undrained (CU) Triaxial Test

Need and Scope:

To find the shear strength parameters (c', Φ') of soil for effective stress analysis. CU triaxial test is recommended for all types of soil including cohesive and cohesionless soils. Pore pressure evolution with in the soil mass can also be studied in CU tests, along with stress-strain response of soil.


In CU test, drainage is allowed during application of confining pressure (σc) and the specimen is fully consolidated by allowing drainage and it is ensured by observation that no further drainage occurs after sufficient time under the applied pressure. The specimen is then allowed to shear when consolidation is over. During that stage, drainage line is closed and the soil sample is sheared by application of deviator stress (σd; at failure: σd = σf). uf is the pore pressure generated within the soil specimen due to deviator stress at failure. CU triaxial test provides the shear strength parameters for total stress analysis (c, Φ) as well as effective stress analysis (c', Φ')

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