ERTH 2415 Lecture Notes - Lecture 1: Silt, Quick Clay, Tacticity
16 Feb 2017
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Document Summary
Mass movement downslope movement of earth materials under the direct influence of gravity. When driving force > resisting force then mass movement takes place. The driving force is the component of gravity parallel to the slope. The resisting force is proportional to inertia and friction and counteracts the driving force. Steepness and stability are indirectly proportional: removing support at the base of the slope, removal of lateral support decreases stability. Internal conditions of slope instability : presence of weak material, material that experiences plastic deformation due to stress e. g. clay. Friction force that resists motion between 2 surfaces in contact. Friction depends on the roughness of the surface and the presence of lubricants: fractures in rock fractures oriented in the slope direction are particularly unstable. Internal roles of water: adding weight to porous earth materials, dissolving cement binding minerals together. Change from water to ice, 9% volume increased. Favourable conditions moist environment, temperature fluctuating around freezing point.
