2016 -2017 Soil Mechanics Lectures Third Year Students
Includes: Stresses within the soil, consolidation theory, settlement and degree of consolidation, shear strength of soil, earth pressure on retaining structure.: Soil Mechanics Lectures /Coarse 2------2016-2017------Third year Student
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Soil Mechanics Lectures /Coarse 2------2016-2017------Third year Student
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Soil Mechanics Lectures /Coarse 2------2016-2017------Third year Student
Stresses within the soil
Stresses within the soil:
Types of stresses: 1- Geostatic stress: Sub Surface Stresses cause by mass of soil a- Vertical stress = b- Horizontal Stress ℎ = Note : Geostatic stresses increased lineraly with depth.
2- Stresses due to surface loading : a- Infintly loaded area (filling) b- Point load(concentrated load) c- Circular loaded area. d- Rectangular loaded area.
Introduction:
At a point within a soil mass, stresses will be developed as a result of the soil lying above the point (Geostatic stress) and by any structure or other loading imposed into that soil mass.
1- stresses due Geostatic soil mass
(Geostatic stress) = ℎ , where : is the coefficient of earth pressure at = rest.
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Soil Mechanics Lectures /Coarse 2------2016-2017------Third year Student
EFFECTIVESTRESS CONCEPT: In saturated soils, the normal stress ( σ) at any point within the soil mass is shared by the soil grains and the water held within the pores. The component of the normal stress acting on the soil grains, is called effective stressor intergranular stress, and is generally denoted by σ'. The remainder, the normal stress acting on the pore water, is knows as pore water pressure or neutral stress, and is denoted by u. Thus, the total stress at any point within the soil mass can be written as: + u This = applies to normal stresses in all directions at any point within the soil mass. In a dry soil, there is no pore water pressure and the total stress is the same as effective stress. Water cannot carry any shear stress, and therefore the shear stress in a soil element is carried by the soil grains only.
1- W.T.L very deep