The measurement of liquefaction phenomena by resistivity and its evaluation

摘要

It is considering that the liquefaction occurs whenthe frame structure of particle in the loose sand layer is collapsedby over pore water pressure due to the earthquake motion. In otherwords, the shear resistance penetration test or the monitoring ofpore water pressure and becomes zero. The N value by the standardpenetration test or the monitoring of pore water pressure is usedfor understanding and evaluation of liquefaction so far. Thesetechniques, however, cannot directly observe the porosity of sandthat corresponds to the change of particle structure in the sandlayer. In this paper, the results of the resistivity monitoring forliquefaction was reported and the process of liquefaction fromthose results was considered by using Archie's law.As the result, it became clear that the liquefaction processconsidered from those results did not contradict the ordinarymodel, namely, the floating and sedimentation model of the sandparticles. Moreover, we referred to the possibility of the floatingof particle near the sand layer surface in the progress of liquefaction.Finally, we proposed the new evaluation method of theliquefaction layer which combine the resistivity of collected sandin a laboratory test with the resistivity obtained by resistivity logging.