stress distribution 2
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Stress Distribution
in Soil Mass–
Part 2
KAEA 3233 - SOIL MECHANICS II
Dr. Tan Chee GhuanDepartment of Civil Engineering
Faculty of Engineering
University of Malaya1
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2
Pressure distribution diagrams
• Stress varies along depth as well as
horizontal distance.
• Vertical pressure on a given
horizontal plane is same in all
directions at equal radial distance
from the axis of loading.• An ‘isobar’ is a stress contour or a
curve which connects all points
below the ground surface with the
same vertical stress.• An isobar is a spatial curved
surface and resembles a bulb in
shape. The stress isobar is also
called ‘pressure bulb’.
Isobar
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Pressure distribution diagrams
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Significant depth
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Significant depth
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Example 2
7
A single concentrated load 1000 kN acts at the ground surface.
Construct an isobar for a vertical pressure of intensity 40 kN/m2. Use
Boussisesq formula.
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Vertical Stress Caused by a Line Load
8
• Road, railway traffic, walls and etc.
• The vertical stress in a soil mass due to a vertical
line load can be obtained using boussinesq’s
solution.
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Vertical Stress Caused by a Line Load
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Vertical Stress Caused by a Line Load
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Vertical Stress Caused by a Strip Load
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• Exterior Wall Foundation
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Vertical Stress Caused by a Circular Load
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Vertical Stress Caused by a Circular Load
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Example 3
15
A ring footing of external diameter 8m and internal diameter 4m
rests at a depth of 2m below the ground surface. It carries a load ofintensity 150 kN/m2. Find the vertical stress at a depths of 2m, 4m
and 8m along the axis of the footing below the footing base.
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