Physical Properties of Roc1

Physical Properties of Roc1 - water with a surface area...

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Physical Properties of Rock, Soil and Water Soil strength shear strength (S) resistance to shear force = f(normal force, friction, cohesion, pore pressure) friction mechanical resistance internal friction (phi) = plane friction (between plane surfaces) + interlocking friction (resistance due to roughness of surfaces) angle of repose : angle of rest of dry sediment,typically 25-40 o depending on particle size sliding angle: angle at which dry sediment fails, up to 10 o greater than the angle of repose angle of static friction > angle of dynamic friction, because failing material has momentum and usually comes to rest at angles < the angle of repose cohesion (c) produced in rock by fusion of minerals or cementing of grains; eliminated by fracturing (brittle failure) in sediment results from electrostatic forces among fine particles (especially clay) and
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Unformatted text preview: water with a surface area &gt;&gt; than mass, clay particles carry a negative charge and thus cohere in the presence of water (bipolar molecules) y-intercept on the plot of normal stress versus shear strength cohesion increases with soil moisture but only to a threshold above which porewater pressure forces particles apart counteracting normal force and reducing friction pore pressure (p) portion of the normal stress supported by air and water in interstitial spaces when soil is saturated, p = porewater pressure (u) &gt; 0 effective normal stress = normal stress - u, the stress exerted at grain contacts producing internal friction positive porewater pressure is a buoyant force, that is, is supports part of the weight of the soil and therefore wet sediment has very low shear strength...
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