An energy-based excess pore pressure generation model for cohesionless soils

In 1976, J.R. Booker, M.S. Rahman, and H.B. Seed developed a computer program for the analysis of pore pressure generation and dissipation during cyclic or earthquake loading. The pore pressure generation model used by Booker et al. (1976) is a two-parameter stress-based model. Their study marked one of the first attempts to model effective stresses in cohesionless soils during earthquakes. The authors have developed a single parameter, energy-based pore pressure generation model, denoted as the GMP model. The motivation for the development of an energy-based model is for application to projects and problems involving liquefaction for soil densification and ground improvement purposes. The GMP model is an empirical relation between dissipated shear energy and the residual excess pore pressure ratio, r(u). The model has accurately approximated r(u) in samples of sand and silt-sand mixtures at various densities tested in cyclic triaxial, cyclic torsional shear, and in large-scale shake table tests. A comparison of r(u) values measured in cyclic triaxial samples with those computed using both the energy-based GMP model and the stress-based model used by Booker et al. (1976), shows that both models give good results. Because the GMP model has a simple mathematical form and a single calibration parameter, it is easy to implement and calibrate. A preliminary correlation between the GMP model's single calibration parameter and relative density is presented for fine sand.