Laboratory Investigation of Liquefaction Behavior on Sloping Ground: Insights from Physical Models
Yelvi(1), Adrin Tohari(2), Abdul Hakam (3), Jafril Tanjung (3), and Arifan Jaya Syahbana (2)

(1)Postgraduate Student of Civil Engineering Department, Faculty of Engineering, Univesity of Andalas, Indonesia
(2) Research Centre for Geological Disaster, ORKM, BRIN, Jalan Sangkuriang, Dago, Bandung, 40135, Indonesia
(3) Engineering Faculty, University of Andalas, Indonesia

Abstract

Massive flow liquefaction disaster occurred during the 28 September 2018 in Palu City and Sigi regency. In order to understand the factors controlling of the initiation of such liquefaction, a series of laboratory liquefaction experiments was conducted using a one-axis shaking table. This study aims to investigate the effect of relative density and slope on liquefaction behavior. Soil layer density modeling was conducted based on the results of field investigations in Palu City and Sigi Regency, which identified layers of dense sand, loose sand, and medium sand. Two soil model samples, measuring 1500 mm in length and 400 mm in width, were placed in a rigidly constructed liquefaction tank. The geometry of the loose sand and medium sand layers was formed with slopes of 0%, 3%, and 5%, with varying water heights. Three pore-water pressure sensors were installed in the loose sand layer to observe the excess pore-water pressure (EPWP) development during the shaking. The results of the experiments showed that the thickness of the unsaturated medium layer affected the increase in EPWP values in the loose sand layer. The percentage increase and decrease in the thickness of the medium sand layer is proportional to the increase and decrease in the EPWP value. In Model #1, both the thickness of the medium sand layer and the EPWP value exhibit a 100% increase, followed by a decline once the thickness reaches 100%. Additionally, the thickness of the medium sand layer prevents the EPWP value from influencing the slope of the loose sand layer, which has an upper slope limit of 5%, as observed in Model #2. The results of this study will be used for further research with sand deposit models and a more in-depth analysis of flow liquefaction.

Keywords: Excess pore water pressure, Flow liquefaction, Shaking table

Topic: Soil sciences