Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

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Numerical Model of Antecedent Rainfall Effect on Slope Stability at a Hillslope of Weathered Granitic Soil Formation


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1 Department of Civil and Structural Engineering, University Kebangsaan Malaysia, India
     

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Modeling rainwater infiltration in slopes is vital to the analysis of slope failure induced by heavy rainfall. Although the significance of rainwater infiltration in causing landslides is widely recognized, there have been different conclusions as to the relative roles of antecedent rainfall to slope failure. In this study, a numerical model was developed to estimate the effect of antecedent rainfall on an unsaturated slope, the formation of a saturated zone, and the change in slope stability under weak rainfall and rainstorm event. Results showed that under a rainstorm event, slope failure occurred at comparably similar time although the antecedent rainfall drainage periods prior to the major rainfall were different (i.e., 24-h, 48-h and 96-h). However, under weak rainfall condition, differences of the antecedent rainfall drainage periods have significant effect on development of pore-water pressure. A higher initial soil moisture conditions caused faster increase in pore water pressure and thus decreasing the safety factor of the slope eventually increasing likelihood of slope failure.

Keywords

Slope Stability, Weathered Soil, Numerical Models, Rainfall.
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  • Numerical Model of Antecedent Rainfall Effect on Slope Stability at a Hillslope of Weathered Granitic Soil Formation

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Authors

Muhammad Mukhlisin
Department of Civil and Structural Engineering, University Kebangsaan Malaysia, India
Mohd Raihan Taha
Department of Civil and Structural Engineering, University Kebangsaan Malaysia, India

Abstract


Modeling rainwater infiltration in slopes is vital to the analysis of slope failure induced by heavy rainfall. Although the significance of rainwater infiltration in causing landslides is widely recognized, there have been different conclusions as to the relative roles of antecedent rainfall to slope failure. In this study, a numerical model was developed to estimate the effect of antecedent rainfall on an unsaturated slope, the formation of a saturated zone, and the change in slope stability under weak rainfall and rainstorm event. Results showed that under a rainstorm event, slope failure occurred at comparably similar time although the antecedent rainfall drainage periods prior to the major rainfall were different (i.e., 24-h, 48-h and 96-h). However, under weak rainfall condition, differences of the antecedent rainfall drainage periods have significant effect on development of pore-water pressure. A higher initial soil moisture conditions caused faster increase in pore water pressure and thus decreasing the safety factor of the slope eventually increasing likelihood of slope failure.

Keywords


Slope Stability, Weathered Soil, Numerical Models, Rainfall.

References