Three-dimensional geological modeling of Phnom Penh subsoils

Abstract

In the past, geological and geotechnical data were illustrated only on paper maps and report. Nowadays by the modernization of computer technique, Geographic Information System (GIS) and three-dimensional (3D) modeling are the most common tools applied to store, analyze, and implement those data. In Phnom Penh city, there have been an increasing number of sub-surface investigations for infrastructure construction in recent years. As a result this master thesis presents a methodological approach to organizing and modeling the geotechnical database. Solid models from borehole data are presented via Groundwater Modeling System (GMS) using horizon method. This method is used to build solid model directly from the boreholes by assigning horizon IDs to each of the borehole contact. The solid model is then built by interpolating each of the surfaces defined by the horizons and extruding the surface into a solid. On the other hand, the geotechnical characteristics of the subsoil are now better understood through underground investigation all over Phnom Penh city. A series of subsurface investigations including in-situ and laboratory tests have been carefully planned and carried out for residential and commercial development. Therefore, another part of this master research illustrates a summary of typical geological condition and their geotechnical parameters for each district of Phnom Penh city. In addition, Mekong river sand is one the most typical fill material for embankment and road construction so that the properties of sand should be considered for this research study as well.