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Erg Chebbi, Morocco. The effective stress can be defined as the stress, depending on the applied tension and pore pressure , which controls the strain or strength behaviour of soil and rock (or a generic porous body) for whatever pore pressure value or, in other terms, the stress which applied over a dry porous body (i.e. at =) provides the same strain or strength behaviour which is observed ...
In terms of effective stresses, the shear strength is often approximated by: = σ' tan(φ') + c' Where σ' = (σ - u), is defined as the effective stress. σ is the total stress applied normal to the shear plane, and u is the pore water pressure acting on the same plane. φ' = the effective stress friction angle, or the 'angle of internal ...
Terzaghi's Principle states that when stress is applied to a porous material, it is opposed by the fluid pressure filling the pores in the material. [1]Karl von Terzaghi introduced the idea in a series of papers in the 1920s based on his examination of building consolidation on soil.
When the water pressure at a point in the soil is equal to the total vertical stress at that point, the effective stress is zero and the soil has no frictional resistance to deformation. For a surface layer, the vertical effective stress becomes zero within the layer when the upward hydraulic gradient is equal to the critical gradient. [15]
The coefficient of lateral earth pressure, K, is defined as the ratio of the horizontal effective stress, σ’ h, to the vertical effective stress, σ’ v. The effective stress is the intergranular stress calculated by subtracting the pore water pressure from the total stress as described in soil mechanics. K for a particular soil deposit is ...
The first equation determines the magnitude of the deviatoric stress needed to keep the soil flowing continuously as the product of a frictional constant (capital ) and the mean effective stress ′. The second equation states that the specific volume ν {\displaystyle \ \nu } occupied by unit volume of flowing particles will decrease as the ...
This parameter is called the effective stress of the soil, basically equal to the difference in a soil's total stress and pore water pressure. The pore water pressure is essential in differentiating a soil's total stress from its effective stress.
Soil liquefaction occurs when the effective stress (shear strength) of soil is reduced to essentially zero. This may be initiated by either monotonic loading (i.e., a single, sudden occurrence of a change in stress – examples include an increase in load on an embankment or sudden loss of toe support) or cyclic loading (i.e., repeated changes ...