Elastic Parameters And Velocity Calculation In Multi-phase Materials

Based on quasi-static hypothesis, some parameters of Boit-Gertsma's elastic theory which could not be directly perceived through the senses, was showed by explicit physical parameters. In spite of modifying coefficient, a modifying term is used to modify Brandt's theory of sphere grain model ; this term's expression has been acquired , and the result is identical to Biot-Geertsma's theory in form and quantity, in which the two classics theories is in perfect harmony .It is also confirmed that the constitutive relation of Carroll and N.Katsube theory, and the bulk modulu of Kuster scattered waves are identical to Biot theory. Serial and parallel stress-strain relations in saturated soils have been theoretically deduced from un-drained stress-strain relations with a new condition of frame volume deformation equaling to total volume deformation, which were suggested for the first time in this thesis and proved a theoretical method to choose suitable mechanical models. The mechanipal model for saturated soils with isolated holes has been discussed in a new more reasonable way and the stress-strain relations and bulk moduli for this kinds of soils have been supposed. A new concept, the skeleton elastic wave velocity (SEWV), was introduced to replace the velocities of dry soil, which could reflect the engineering characteristic of soil more accurately .New methods to calculate SEWV from measured velocities in saturated soil were suggested. The longitudinal wave velocity in saturated soil could not only be useful , but reflect more information as well. The shear wave velocity may be different from the shear SEWV ,the difference is proved to be caused by porosity and structure factor. The fact that wave velocity in quasi-saturated soil is equal to that of fully saturated soil could not be calculated by effective fluid compressibility or explained by unwell-distributed saturation .We account for this in a new reasonable way which was based on Kuster scattering effect analysis. Based on the concepts of elastic wave velocity of skeleton and reinforced cohesion, the effect on the velocity by soil density with different saturation was distinguished from that by weakened reinforced cohesion; On the condition of same confined press and saturation, the elastic wave velocity was measured before and after soil samples were dynamically loaded, so that the elastic wave velocity changed by dynamic load was distinguished from that by soil.nature characteristic. Some regular patterns of reinforced cohesion and velocity in loess under different saturation and dynamic load have been discussed in a preliminary way. Some results of this research was applied in practical work and certain effect has bas been acquired.