A Study on the Mechanism of Internal Erosion Resistance to Soil Slope Instability

Fauzilah Ismail

Faculty of Civil Engineering, Universiti Teknologi MARA, Malaysia

Zainab Mohamed

Dean, Faculty of Civil Engineering, Universiti Teknologi MARA, Malaysia

Mazidah Mukri

Faculty of Civil Engineering, Universiti Teknologi MARA, Malaysia

 

ABSTRACT

A study has been conducted to determine the mechanics of internal soil erosion resistance associated with seepage and leakage which possibly contribute to the cause of slope instability. A higher probability and risk of slope failure after prolonged heavy rainfall or antecedent rainfall has been reported; hence this in-depth study of the failure mechanism is initiated. The infiltration of rainwater through the slope surface creates a path within the soil mass and/or flowing through a crack surface which can penetrate meters in depth. When the soil particles disperse into suspension and transported by water along the flowing movement, the removed particles will lead to internal erosion process. A laboratory study has been carried out to characterize the internal erosion resistance to slope instability due to infiltration and the effect of percentage of coarse to fine-grained soil composition. A pinhole test, crumb test and cylinder dispersion test were conducted to investigate the soil dispersibility characteristic. A set of randomly selected soil samples were extracted from soil slopes within UiTM, Shah Alam Campus. Samples were collected before and after rainfall. Initial result showed that soil is prone to disperse near dry or at lower moisture content. Soil samples with higher composition of coarse-grained particles have higher dispersibility that lead to lower resistance to internal erosion.

Keywords: Internal erosion, Rainwater Infiltration, Sloping Soil, and Soil Dispersibility

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