Creating a Liquefaction Hazard Map in 3D Formulation

The Korea Institute of Civil Engineering and Building Technology has successfully developed a “3D liquefaction hazard map” that visually displays ground liquefaction predictions in the event of an earthquake.

Liquefaction is a phenomenon in which the Earth’s surface loses its solidity and acts as a liquid due to the repeated application of large forces generated by an earthquake. It can cause buildings or other structures to tilt or collapse, resulting in huge losses in terms of life and property.

The phenomenon, which became widely known after the 1964 Niigata and Alaska earthquakes, wreaked havoc across a wide swath of land in the 2011 Christchurch and Great East Japan Earthquake. To date, liquefaction-related damage has been frequently reported worldwide.

A research team (Dr. Han, Jin Tae, Dr. Kim, Jungkwan) in the Geotechnical Engineering Research Department of KICT developed a 3D liquefaction hazard map linked to the Korea Geotechnical Information Portal, a database system for ground data. The map displays liquefaction hazards by region in 3D when an earthquake occurs.

Land made up of soil tends to maintain its solid state until it becomes more liquid-like in the process of liquefaction, which is known as resist liquefaction. The liquefaction resistance varies in different regions according to the soil composition characteristic of each region.

The research team calculated the safety factor against liquefaction by comparing the forces applied to the ground caused by the earthquake and the resistance of the soil to liquefaction. To calculate regional liquefaction resistance, the team used the Geotechnical Information Portal database created by KICT. She then presented a three-dimensional liquefaction risk map by visualizing the safety factors through the depth of the earth.

Typically, two-dimensional liquefaction hazard maps are generated because most structures are built on the surface of the earth. However, such maps are not enough in places like Korea that make the most of underground space due to limited land, as they are unable to accurately identify hazards underground. However, the 3D map can identify hazards in underground spaces as well as those on the ground.

The research team also improved the existing spatial interpolation method to apply it to the 3D map. Spatial interpolation is the process of estimating values ​​at unknown points using points with known values.

KICT has integrated its 3D liquefaction risk map with S-Map OpenLab, the Seoul Metropolitan Government’s spatial data platform. S-Map is a 3D virtual reality version of Seoul that is designed to help make policies in various fields including safety, environment, city planning and urban problem solving. The integration of the 3D liquefaction map and the S-Map is expected to enable risk monitoring of structures not only in underground spaces but also on the ground.

Dr. Han, Jin Tai, who led the research, said, “Three-dimensional liquefaction risk map in relation to the national geotechnical information portal system is expected to develop related technology because the map includes three-dimensional ground data for the safe management of subway spaces. The integration of the map with Map S in Seoul will serve as a model that can be applied to a variety of related fields.”

The work has been published in the journal applied Sciences.