抄録
When a saturated sand is subjected to earthquake excitation under undrained conditions, excess pore water pressure is generated, and the effective stress decreases. This eventually leads to sand liquefaction. It is important to analyze the liquefaction phenomena, particularly for the earthquake-resistant design of structural foundations. Although many experimental studies on liquefaction have been performed, their results have not well implemented in developing analytical models. In this study, the dynamic response of horizontally layered soil is numerically analyzed, using the stress-strain relation of sand and the equation of motion for two-phase mixtures consisting of an incompressible fluid and an elastic-plastic solid. As the mixture of pore water and soil particles is assumed to be incompressible, effective stress analysis is appropriately applied. In the case of a horizontally layered soil deposit, deformation should be horizontally confined during earthquakes. In this study, therefore, the horizontally confined condition is considered. By using this condition, stress path particular to the liquefaction process can be obtained analytically. The effect of the dissipation of pore water pressure due to seepage on the response of the ground is also examined. It is concluded that liquefaction greatly influences the dynamic response of ground.
