Unsaturated soil mechanics for sustainable urban development

Harianto Rahardjo, A. Satyanaga

Research output: Contribution to conferencePaperpeer-review

1 Citation (Scopus)


The effects of climate change are major concerns for many tropical urban areas, like Singapore. Singapore is mainly covered by residual soils with a significant thickness of unsaturated zone above the groundwater table. In practice, geotechnical engineers commonly ignore the unsaturated soil mechanics in their design to avoid the complexity of analyses. However, the ignorance of the unsaturated soil mechanics can lead to the over conservative designs that may not be sustainable. In most geotechnical designs, such as slope stability, tree stability and deep excavation, the actual flux boundary conditions will be an important concern. Flux boundary conditions (i.e. infiltration, evaporation, transpiration) produce an unsteady-state saturated/ unsaturated flow situation which results in a change in the pore-water pressure and shear strength of soil. Therefore, the effect of climate change, which is translated into flux boundary conditions, should be considered not only in geotechnical design, but also in the assessment of natural structures like slopes and tree stability using the unsaturated soil mechanics principles. This paper presents the application of unsaturated soil mechanics for sustainable urban development. Slope and tree failures may damage surrounding buildings, infrastructure, vehicles as well as cause injuries or fatalities. Therefore, sustainable preventive measures for slope protection against rainfall and for maintaining tree stability are required. As a case study, this paper describes the development of slope susceptibility map with the incorporation of unsaturated soil properties in Singapore. The preventive measure for slopes that fall under the categories of slopes with low factor of safety should be provided. In this paper, the use of capillary barrier system and geobarrier system, that incorporates unsaturated soil mechanics principles and recycled materials, for slope preventive measures against rainfall is presented. In addition, the use of soil mixtures for maintaining tree stability with the unsaturated soil mechanics consideration is also illustrated in this paper. In general, the studies presented in this paper illustrate the successful application of unsaturated soil mechanics principles in slope and tree stability with the main consideration of sustainable developments in urban areas.

Original languageEnglish
Publication statusPublished - 2020
Externally publishedYes
Event16th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2019 - Taipei, Taiwan
Duration: Oct 14 2019Oct 18 2019


Conference16th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2019


  • Recycled materials
  • Slope stability
  • Sustainable urban development
  • Tree stability
  • Unsaturated soil mechanics

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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