## Shear Behavior: Short-Term and Long-Term

### Reminder :

Soils consist of three phases: solid, liquid, and gas. It is essential to distinguish between effective stresses and total stresses.

### Definition :

Granular Soil with high permeability allows rapid drainage under external loads. Shear behavior and strength are governed by the solid skeleton.

Fine Soils: with low permeability results in slow drainage. Two extreme behaviors are observed:

- Short-Term Behavior: Undrained conditions, where water plays a significant role in mechanical behavior.

- Long-Term Behavior: Drained conditions, where pore water pressures dissipate, and behavior is governed by the solid skeleton.

Drained and undrained conditions

Several types of tests are used to determine the plasticity characteristics; these include:

In-situ measurement tests (vane shear test, penetrometer, etc.),

Laboratory tests (unconfined compression test, direct shear test or Casagrande shear box, triaxial compression test).