Visualization of Liquefaction in Soils with PWP Measurements by Tapping

Abstract

While sandy silty soils, especially in the river delta area are subjected to liquefaction due to high-intensity earthquakes, the geotechnical profession has gone far and wide in the determination of liquefiable/non-liquefiable zone based on the semi-empirical methodology since the 1970s. Moreover, cyclic triaxial, as well as simple shear tests, on soils have been exploited sequentially to recreate pre- and post-liquefaction situations. There are few laboratory studies to capture the liquefaction effect in soils when subjected to dynamic excitations. In this paper, the effect of manual tapping on the small–medium–large containers filled with soil–water, both visualization of the liquefaction phenomena and measurement of excess PWP has been explained. Simulation of underground utilities and overground buildings in a liquefiable soil has been done with rubber balls affixed with a needle. Capturing the upward movement of the rubber balls and downward movement of the needle fixed rubber balls vis-à-vis instant jumping of water level in the open standpipe piezometer, are some of the unique experimental findings. The results show that out of nine types of soils specimen, the Yamuna River sand in Delhi and the Khowai River sand in Agartala, India, are highly liquefiable, and equivalent PWP variation during dynamic excitation has been measured and simulated during the experiment.