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Book chapter · CRC Press eBooks · September 23, 2020

Effect of dual-porosity material on stability of slope during rainfall

Alfrendo Satyanaga, Harianto Budi Rahardjo, Eng‐Choon Leong, Y.H. Chia, J.-Y. Wang

Alfrendo Satyanaga Nio
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Abstract

Analysis of water flow in unsaturated soils or waste materials is very important in many geotechnical and geoenvironmental applications, such as construction of earth dams and dikes, protection of groundwater resources from chemical pollution, or protection of landfill system. Many seepage analyses commonly ignore the presence of bimodal pore-size distribution that commonly exists in dual porosity structure of some residual soils or waste materials. A unimodal equation is usually used to model the bimodal hydraulic properties of soil in order to simplify the numerical analyses. However, the bimodal properties of a soil in the field can be a significant factor in affecting water flow within this soil during rainfall. This paper focuses on the effect of dual porosity material on stability of slope during rainfall. In this study, new bimodal equations are presented and used to model the hydraulic properties of dual-porosity material. The bimodal equations are incorporated in the numerical model to understand the variation of factor of safety of slope with dual-porosity material. The variations of factor of safety of slope during dry and rainy periods computed from slope stability analyses using the bimodal equations are larger than those from slope stability analyses using the unimodal equations. The rates of changes in factor of safety resulted from slope stability analyses using the bimodal and unimodal equations are different and dependent on the average relative error of the equation used to best fit the soil-water characteristic curve of the dual-porosity material. In conclusion, the soil-water characteristic curve and permeability function of dual-porosity material can be modeled using unimodal equation to simplify the seepage and stability analyses for rainfall intensity of less than 9 mm/h.

Soil and Unsaturated FlowGeotechnical Engineering and AnalysisGeotechnical Engineering and Soil Stabilizationslope stabilityrainfallbimodal pore size distribution

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