I have a rock specimen and a soil specimen. During my mechanical measurements I observed that the rock reacts much faster on stress rate changes (observable by a sharp kink in the deformation curve) than a soil (no such kink). What is the explanation? Where can I find a publication dealing with this phenomenon?
The first thought is that elastic waves propagation takes place. Corresponding velocities are proportional to sqrt of elastic moduli. See, for example, https://petrowiki.org/Compressional_and_shear_velocities
The first thought is that elastic waves propagation takes place. Corresponding velocities are proportional to sqrt of elastic moduli. See, for example, https://petrowiki.org/Compressional_and_shear_velocities
Victor J. Аdlucky
Thank you for your answer. But I forgot to mention that my question relates to a static load.
Hi, a consolidated material like a weakly cracked rock under a relatively low stress increase, the deformation is faster than that of a soil which takes time under the effect of the constraint, to close the cracks which it comprises; likewise for a highly cracked rocky material.
Dear Christian,
For rock, a electromagnetic wave propagation theory does work. If a material is stiff, then it must be strong enough to support a large load. In soft soil(you mention soft soil), large load is not required, but as far as stiffness concern, rock is more stiff, cohesive strength of rock 10000 KPa is much high in comparison to soft soil. Displacement produced by the force along the same degree of freedom in soil is less in comparison to rock.
However, electromagnetic wave propagation, correct electromagnetic ground constants for the applicable frequency, conductivity vs. frequency and dielectric constant vs. frequency indicates that compressive strength rebounding is less and subsequently shear also less. so stress changes due to deformation in soil is higher in comparison to rock which has less deep penetration, wave propagation in form of crack arrest will be low.
In my opinion, stress change occurs faster in case of soil due to damping nature. However jumping wave frequency is higher in rock.
Hope it work out for you.
Ashish
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