Pore Pressure Generation and Dissipated Energy Ratio in Cohesionless Soils

Under cyclic loading, loose, saturated cohesionless soils develop excess pore pressures and decreased effective stresses and thus, decreased strengths. Lee and Albaisa showed that when pore pressure ratio is plotted against cycle ratio (the ratio of the current cycle of loading to the number of cycles of loading required to initiate liquefaction), the results plotted within a relatively narrow band. Excess pore pressure generation during cyclic loading has also been shown to be proportional to the energy dissipated in the soil during loading. The study reported here used the results of over 135 cyclic triaxial tests performed on sands and non-plastic silts to determine that when pore pressure ratio was plotted against dissipated energy ratio (the ratio of the cumulative dissipated energy to the dissipated energy required to initiate liquefaction), the relationship between pore pressure ratio and dissipated energy ratio is independent of the specimen's relative density, silt content, magnitude of loading, number of cycles of loading required to initiate liquefaction, and normalized dissipated energy per unit volume required to cause liquefaction in the specimen.