THE PREDICTION OF THE EXCESS PORE WATER PRESSURE GENERATION AND THE VERTICAL STRAIN IN DIFFERENT CYCLIC STRESS RATIO LOADINGS UNDER ANISOTROPIC UNDRAINED CONDITION

The liquefaction phenomenon and its effect under seismic loading has been described, defined, and experimented both in the laboratory and in the field via renowned researchers. The excess pore water pressure generated by the cyclic loading causes the effective stress diminishing down close to zero in order to induce the initial liquefaction. During or after the earthquakes, the ground shaking causes a loss of cohesionless soil’s mechanical strength or stiffness associated with the large settlement on the ground surface. Once the soil liquefied, the large settlement of ground surface will prompt the damage, disfunction or collapse in structure aspect.

In fact, the nature soil layers deposit commonly in medium dense to dense status which is not effortless to approach fully liquefaction under seismic loading especially under anisotropic condition. However, the seismic loading still induces the excess pore water pressure increasing and the light vertical settlement during the earthquake. The agendas of this study focus on the prediction of the vertical strain and the excess pore water pressure generation in different cyclic stress ratios loading (0.1 to 0.4) under anisotropic undrained condition. The soil specimens include 3 different particle size materials prepared in 3 different relative density conditions (medium dense, dense and very dense). The consequence provides useful charts to predict the vertical soil strain in order to evaluate the settlement of structure during the earthquake.