Additional data

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Additional data


Additional data: Shear modulus, density, plasticity index, etc. are necessary to calculate the increase of pore pressure in seismic field.


Geotechnical behavior: noncohesive, cohesive, noncohesive - cohesive


Dynamic low strain shear modulus: represents the shear modulus at low levels of strain. The threshold is generally set between 0.0001% and 0.001%.


Dynamic shear modulus: represents the shear modulus beyond the threshold of linearity, where the soil has a highly non-linear and dissipative behavior, with a reduction of shear stiffness G.


Relative density: for granular soils this parameter expresses the degree of densification between the particles. It depends on the uniformity or the variability of the particle diameters: more variable the diameter of the soil, the higher will be the relative density. A soil classification based on relative density is shown in the table below.



Relative density (%)


0 - 15

Very low density

15 - 35

Scarcely densities

35 – 65

Avrage densities

65 - 85


85 - 100

Very densities

Classification of soils according to their state of densification



Over-consolidation ratio: is expressed by the parameter OCR and represents the relation between the preconsolidation pressure and the geostatic pressure. Its value is greater than unity for overconsolidated soils.


Plasticity index: is a parameter of the behavior of cohesive soils. Its value is given by the difference between the liquid limit and plastic limit (Atterberg limits).


Number of load cycles required to produce liquefaction: represent the number of cycles of loading and unloading which trigger the liquefaction, ie cancel the effective stress state of the soil (will be calculated automatically by the program).



Theoretical notes Pore pressure




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