National Institute of Advanced Industrial Science and Technology (AIST) This page is a page of the former research institute. We stopped updating on March 31.2001.
E-mail to webmaster (Japanese) E-mail to webmaster (English)
National Institute for Resources and Environment HomePage

NIRE Annual Report
BackContentsNext
 1999

Resistivity of Saturated Sand during Liquefaction Process

Safety Monitoring and Control Division
Safety Engineering Department
Objectives
The check of aseismatic design is done after Hansin-Awaji big earthquake disaster (1995). This study aims to secure the safety of the foundation structure of the industry facilities at the time of the earthquake, and especially we examine a liquefaction phenomenon and lateral large ground deformation due to liquefaction. As the first step of the work, we carried out some experiments to make the liquefaction phenomenon clear.
Results
It is supposed that liquefaction mechanism is closely related to porosity of saturated sand. On the other hand, it is well known that porosity and resistivity are intimately related by the equation of Archie. In consideration of above mentioned relations, saturated sands having several relative densities between 65% and 30% were set up, and resistivities during sinusoidal vibration excitation at three accelerations (100gal, 200gal, 400gal) in two Hz were measured. Fig. 1 shows the apparatus. A parallel electric current flowed between copper meshes, and resistivity (M1) between electrode 2 and 3, and resistivity (M2) between electrode 3 and 4 were measured in every 0.1 second.
Fig.1. Experimental apparatus
Fig.1. Experimental apparatus
Fig. 2 shows the result at relative density 34% and 200gal. Before making the container vibrate, M1 and M2 showed initial resistivities. After excitation, the resistivities revealed the behavior as shown Fig. 2. These behavior can be thought to cope with each of the liquefaction mechanisms, namely, floating condition of sand particles in the A area, sedimentation process in the B area and re-accretion condition after liquefaction in the C area rationally. From the results, it was clarified that the resistivity change was closely related to porosity even under the dynamic vibration and it became clear that it was effective to measure the resistivity to realize the liquefaction mechanism.
Fig.2. Resistivity changes of saturated sand (Dr=34%) during vibration at 200gal in two Hz.
Fig.2. Resistivity changes of saturated sand (Dr=34%) during vibration at 200gal in two Hz.

BackContentsNext










National Institute for Resources and Environment