Differences between triaxial test and shear box test?

Answer 1

Shear box tests are generally suitable for cohensionless soil except fine sand and silt whereas triaxial test is suitable for all types of soils. Pressure changes and volume changes can be measured directly in triaxial test which is not possible in shear box test. Pore water pressure can be measured in the case of triaxial test which is not possible in direct shear test. Triaxial machine is more adaptable. The stress distribution across the soil sample in the failure plane is more uniform in triaxial test. The complete state of stress is known at all intermediate stages up to failure during the triaxial test whereas only the stress at failure are known in the direct shear test. In triaxial test, there is complete control over the drainage conditions, where control of drainage conditions is very difficult in shear box test.