Numerical analysis of effective soil porosity and soil thickness effects on slope stability at a hillslope of weathered granitic soil formation

Muhammad Mukhlisin, Mohd. Raihan Taha, Ken'Ichirou Kosugi

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Modeling rainwater infiltration in slopes is vital to the analysis of slope failure induced by heavy rainfall. Amongst the soil hydraulic properties, the hydraulic conductivity K has been frequently analyzed for its effects on slope stability. In contrast, few studies have been published on the effects of water retention characteristics on slope stability. In this study, a numerical model was developed to estimate the extent of rainwater infiltration into an unsaturated slope, the formation of a saturated zone, and the change in slope stability. This model is then used to analyze the effects of the soil porosity parameters (i.e., saturated soil water content θ s and effective soil porosity (ESP)) and soil thickness on the occurrence of slope failure. Results showed that when the surface soil of a slope has a relatively large ESP value, it has a greater capacity for holding rainwater, and therefore delays rainwater infiltration into the subsurface layer. Consequently, the increase in pore water pressure in the subsurface layer is also delayed. In this manner, a relatively large surface layer ESP value contributes to delaying slope failure. Under weaker storm conditions, slope failure tends not to occur when the surface soil has a relatively large ESP value. In addition, the thickness of soil is also a significant parameter in slope stability analysis. A shallow soil depth resulted in greater discharge volume and a lower peak pore water pressure during the major rainfall event, and consequently the slope failure tends not to occur. However a deeper soil depth increased the weight of solids and the soil moisture conditions in the slope consequently increasing the pore water pressure causing slope failure.

Original languageEnglish
Pages (from-to)401-410
Number of pages10
JournalGeosciences Journal
Volume12
Issue number4
DOIs
Publication statusPublished - Dec 2008

Fingerprint

slope stability
hillslope
slope failure
porosity
rainwater
soil
porewater
infiltration
soil depth
soil surface
rainfall
soil formation
effect
analysis
shallow soil
phreatic zone
water retention
hydraulic property
stability analysis
hydraulic conductivity

Keywords

  • Effective soil porosity (ESP)
  • Numerical analysis
  • Rain water infiltration
  • Slope stability
  • Soil thickness
  • Weathered granitic

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Environmental Science(all)

Cite this

Numerical analysis of effective soil porosity and soil thickness effects on slope stability at a hillslope of weathered granitic soil formation. / Mukhlisin, Muhammad; Taha, Mohd. Raihan; Kosugi, Ken'Ichirou.

In: Geosciences Journal, Vol. 12, No. 4, 12.2008, p. 401-410.

Research output: Contribution to journalArticle

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