Introduction to Dynamic Soil Properties

Hi, How have you been?

Soil dynamics is the study of the behavior of the soil under the dynamic loads. When the loads are larger such as the earthquake loads, Blasts or the nuclear explosions, the strain rate of the soil is from 0.01% to 0.1%, while the strain rate in the soil is comparably low of order 0.0001% to 0.001 % in case of the small loading such as the loading on the foundation of the reciprocating machines.

In order to analyse and design the structures subjected dynamic loading, we have to study the following dynamic properties of the soil:

1. Dynamic moduli, such as Young's modulus of Elasticity 'E', Shear modulus 'G', and bulk modulus 'K'.
2. Poisson's ratio
3. Dynamic Elastic constants, such as the co-efficient of uniform compression 'Cu'; Co-efficient of uniform Shear 'Ct', co-efficient of non uniform compression and Co-efficient of non-uniform shear. 
4. Damping Ratio
5. Liquefaction parameters, such as the cyclic stress ratio, cyclic deformation and pore water pressure response.

Dynamic properties of the soil are dependent upon the strain, and several laboratory and field techniques been developed to measure these properties over a wide range of strain amplitude.

Resonant column test, Ultrasonic Pulse test, Cyclic simple shear test, Cyclic torsional simple shear test, and cyclic tri-axial compression tests are the type of the laboratory tests used to determine the dynamic soil properties.

Thank you :)