Laboratory Studies on the Slope Failures of Unsaturated Granular Soil Induced by Rainfall
Date Issued
2010
Date
2010
Author(s)
Chien, Wei-Nan
Abstract
Many previous studies have shown that heavy rainfall reduces slope stability. In the past decade, numerous slope stability studies have been conducted on small model slopes using measurements obtained from instrumentation buried in the model. Previous research focused mainly on the different water supply conditions, rainfall intensity, fine particle content, relative density of soil, slope dimension. Most of those studes were performed on convex slopes using a single sand type. In this study combinations of different variations of conditions such as: fine partical content, rainfall intensity, early rainfall amount, drainage area, slope type (concave slope vs convex slope) and bedrock slope are used to observe the process of slope failure, pore pressure and volumetric water content change. This study used a self-designed industrial spray system to simulate natural rainfall and piezometers installed within the slope to record soil moisture data.
The results showed that: (1) higher fine particle content result in soil volumetric water content and pore pressure increases, which obtain maximum values during slope failure. The fastest and largest landslides were also the earliest to occur. Failure begins as a Circular slump and then transitions into a mud flow. Piping often occurred, and once initiated, pore pressures rapidly declined. (2) Concave slope failure occurred earlier than the convex slope, close to the at the junction between the upper and lower slope in the area of accumulated pore pressure. The debris accumulation area was more wide on the convex slope, but also thinner. (3) As expected, higher rainfall intensity resulted in rapid increases in pore pressure and volumetric water content, moreover failure occurred earlier and failure size increased.
Subjects
Laboratory tests
TDR
Pore-water pressure
Landslide
Fine-particle content
Rainfall Intensity
Type
thesis
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