Geomechanics with Applications to Tunneling and use of Cone Penetrometer for In- Situ Characterization of Soils
Voyiadjis and co-workers formulated the elasto-plastic coupled equations in order to describe the time-dependent deformation of saturated cohesive soils (two phase state). Formulation of these equations is based on the principle of virtual work and the theory of mixtures for inelastic porous media. The theory of mixtures for a linear elastic porous skeleton was first developed by Biot. An extension of Biot’s theory into a nonlinear inelastic media was performed by Prevost. The saturated soil is considered as a mixture of two deformable media, the solid grains and the water. Each medium is regarded as a continuum and follows its own motion. The flow of pore-water through the voids is assumed to follow Darcy ‘s law’. The coupled equations are developed for large deformations with finite strains in an updated Lagrangian reference frame. The coupled behavior of the two phase materials (soil-water state) is implemented in a finite element program. A modified Cam-clay model is adopted and implemented in the fnite element program in order to describe the plastic behavior of clayey soils. Contributions in this area include:
- penetration of a piezocone penetrometer in clay soil is numerically simulated and implemented into a finite element program,
- results of the finite element numerical simulation are compared with experimental measurements conducted at Louisiana State University using the calibration chamber,
- consolidation of clayey and silty soils are successfully conducted at LSU using the calibration chamber in soils,
- numerical simulation is carried out with/without the interface friction between the soil and the piezocone penetrometer,
- results of the numerical simulations compare well with experimental laboratory measurements for the piezocone penetrometer,
- computational simulations are conducted for tunnel boring in soils.
Professor Voyiadjis published a book in this area at the special invitation of a publishing company:
Voyiadjis, G. Z., Voyiadjis, G. Z., and Song, C. R., The Coupled Theory of Mixtures in Geomechanics with Applications, 438 p., Springer-Verlag GmbH & Co.KG, Heidelberg, ISBN: 3-540-25130-8, 2006.