GGR201H1 Lecture Notes - Lecture 3: Pore Water Pressure, Surface Runoff, Drainage Density
11 Jan 2017
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Document Summary
Gravity dominant factor in moving sediment - mass movement or mass wasting. Slope stability - ratio of shear stress to shear strength. Internal friction angle: bulk property, dependent on grain size, water content, cohesion between particles: angle of repose - assumes that the material is completely dry, approximation of friction angle, no effects of surface tension. Saturated soil = lower effective stress due to hydrostatic pressure in pore spaces (pore water pressure) Factors that increase shear stress: removal of lateral support (increase in slope angle), addition of overlying mass or lateral pressure, disturbances (earthquakes, tectonics, vibrations, blasting). Factors that decrease shear strength: weathering (disintegration, freeze-thaw), structural changes (rock fracturing), pore water pressure, sensitivity of failure plain. Talus: slope created by rockfall from bedrock hillslope. Flows: earth flow (slow), debris flow (fast) Creep: frost heave pushes soil up normal to slope, thawing drops soil down vertically.
