Measurement of Coefficient of Consolidation During Reconsolidation of Liquefied Sand

摘要

Saturated sands particularly at low relative density commonly exhibit rises in excess pore pressure when subjected to earthquake loading. The excess pore pressure can approach a maximum value, limited by the initial vertical effective stress. After the completion of earthquake shaking, these excess pore pressures dissipate according to the consolidation equation, which can be solved to produce a Fourier series solution. It will be shown by manipulation of this Fourier series that excess pore pressure traces provide a method for back-calculation of coefficient of consolidation C_v. This method is validated against dissipation curves generated using known values of C_v and seen to be more accurate in the middle of the layer. The method is then applied to data recorded in centrifuge tests to evaluate C_v throughout the reconsolidation process following liquefaction conditions. C_v is seen to fit better as a function of excess pore pressure ratio than effective stress for the stress levels considered. For the soil investigated, C_v is about three times smaller at excess pore pressure ratio of 0.9 compared to excess pore pressure ratio of 0.