A Geotechnical Earthquake Engineering Approach on The Hidden Liquefaction Risks In the Rohingya Refugee Camp Hills & Surrounding Areas of Ukhiya, Cox’s Bazar, Bangladesh

Abstract

The primary focus of this study is on the evaluation of the risk of liquefaction caused by earthquakes using Liquefaction Potential Index (LPI) values for earthquakes with magnitudes of 5.0, 7.0, and 8.0 and peak ground accelerations (a_max.) of 0.28 g in Ukhiya, Cox's Bazar, Bangladesh. During a seismic event, liquefaction—one of the main catastrophic geohazards—typically takes place in saturated or partially saturated sandy or silty soils. A seismically active region's potential for liquefaction should be assessed since doing so can help prevent fatalities and damage to civil infrastructure. Standard Penetration Test (SPT) results have been evaluated for potential liquefaction assessment. These soils are mainly composed of very loose to loose sands with some silts and clays. Geotechnical properties of these very loose sandy soils are very much consistent with the criteria of liquefiable soils. It is established from the grain size analysis results; the soil of the study area is mainly Sand dominated (SP) with some Silty Clay (SC) which consists of 93.68% to 99.48% sand, 0.06% to 4.71% gravel and 0% to 6.26% silt and clay. Some Clayey Sand (SC) is also present. The Silty Clay can be characterized as medium (CI) to high plasticity (CH) inorganic clay soil. LPI values have been calculated to identify risk zones and to prepare risk maps of the investigated area. Based on these obtained LPI values, four (4) susceptible liquefaction risk zones are identified as low, medium, high and very high. The established “Risk Maps” can be used for future geological engineering works as well as for sustainable planning, design and construction purposes relating to adaptation and mitigation of seismic hazards in the investigated area.