Is clay drained or undrained?

Clay behavior depends on the rate of loading (or unloading). When “fast” stress changes take place then clay behavior is typically modeled as “Undrained” while slow stress changes or long term conditions are typically modeled as “Drained”. In the software, the default behavior of a clay type soil is set as “Undrained”.

Why is undrained shear strength important?

The undrained cyclic shear strength has to be evaluated to calculate the capacity under cyclic loads. The undrained cyclic shear strength should be obtained for various stress paths. The remolded shear strength is an important parameter because it is used to calculate the penetration resistance of the skirt walls.

What is CU for clay?

undrained shear strength
The undrained shear strength (cu) is considered one of the most basic para- meter characterizing soils in engineering practice. The particular importance of cu is in the case of clayey soil. This parameter also is the basis for the classification of soil according to the ISO standard.

Is drained or undrained shear strength higher?

Compared to drained strength ( c ′ , ϕ ′ c’, \phi’ c′,ϕ′), undrained shear strength is often much easier and cheaper to measure. It can be derived from an unconfined compression test (UU triaxial), vane shear test or simply using a pocket penetrometer.

How do you test undrained shear strength?

The undrained shear strength is often determined through field and laboratory tests, such as the triaxial test, simple shear test, direct shear test, cone penetration test with and without pore pressure measurements (CPT /CPTU), field vane test and dilatometer test, fall cone tests, and uniaxial and plane strain test.

What affects undrained shear strength?

The increase in undrained shear strength with axial strain rate can be attributed to a reduction in the magnitude of excess pore water pressure, with similar reductions in magnitude for all the degrees of saturation considered.