HOW TO CLASSIFY SOIL SHEAR TEST AS PER DRAINAGE CONDITION?

Shear strength parameters in case of saturated soils depend heavily on drainage conditions and therefore in laboratory shear testing, the expected drainage conditions in the area for a particular problem should be simulated. Shear tests are classified into the following 3 types based on the drainage conditions.

  1. Integrated Untrained Test (UU Test)
  2. Integrated Untrained Test (CU Test)
  3. Integrated Drought Test (CD Test)

1. Integrated untrained test (you you,

Drainage is not allowed during the entire test. In case of direct shear test, drainage is not allowed during use of both normal stress and shear stress. In the case of triaxial compression test drainage is not allowed during application of both cell pressure and divergence stress. Since the test is conducted rapidly, no time is given initially either for the consolidation of the sample or at a later stage to dissipate the pore pressure, hence the test is also called. quick test,

2. Integrated untrained test (cube,

In this type of shear test the soil sample is initially allowed to fully consolidate under applied stress and then quickly sheared without allowing dissipation of pore pressure. In the case of direct shear testing, the specimen is allowed to solidify completely under applied normal stress and then sheared at a high rate of strain to prevent dissipation of pore pressure during shearing. In the case of triaxial compression test the sample is allowed to fully consolidate under applied cell pressure and then the orifice water outlet is closed and the sample is subjected to increasing deflection stress at a high rate of tension.

3. Integrated dry test (CD,

In this type of shear test, drainage is allowed throughout the test. The sample is allowed to fully consolidate under the applied initial stress and then sheared at a low rate of strain giving sufficient time for water to flow out of the pore at all stages. The test can continue for several hours to several days.


Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.