Mechanical properties of soil- Distribution of vertical and horizontal stresses in the soil.
Mechanical properties include the following:
- Distribution of vertical and horizontal stresses in the soil
- Settlement of the soil
- Compaction the soil
- Shear resistance to the soil
- Soil bearing capacity
- Effective lateral pressure of soil
- Slop stability of soil
- The movement of water in the soil under the water compressor
- Swelling pressure of the soil
In this article we will take distribution of vertical and
horizontal stress in the soil and in next articles we will complete all other
mechanical properties.
- Distribution of vertical and horizontal stresses in the soil
When a soil is exposed to vertical loads transported through
the foundation, the soil in this case is subjected to vertical stresses below
the foundation that are quickly affected by the soil grains below and on the
sides of the foundation where that these stresses spread in the soil from its
maximum value directly below the foundation and gradually decrease with
increase in the depth from the bottom of the foundation. And, with the increase
of the dimension and lateral distance from the foundation.
The below figure shows how the vertical stresses transmitted
from the foundation of the building footing are square in shape through lines
equal to the vertical stresses in the soil.
Where it is noted that the vertical stresses decrease to
reach about less than 20% of its value at a depth approximately equal to the
width of the footing.
Based on the above, it becomes clear that the stresses on
the soil not only affect the soil directly below the foundation, but affect the
soil layers in the area adjacent to the foundation or the building, but to a
limited degree depends on the distance of the adjacent layer in relation to
this foundation.
It must be noted that when embarking on the establishment of
a specific building The study of soil properties should not be limited to the
apparent layer at the depth of foundation only, but this study must be extended
to include the substrate layers of the soil below the foundation due to the
possibility of the presence of weak lower layers that may be compressed to a
high degree despite their exposure to relatively weak stresses compared to
those below the foundation and at the level Incorporation is something that
which lead to falling foundations at high values and varying from each other
which lead to damage to the building as a whole.
How to calculate the stress applied to the soil under the foundations.
Calculation of the
vertical stress applied to the soil under foundation by approximately manner
with an slope of 1 horizontal : 2 vertical and accordingly, the average
vertical stress on weak soils ( at the midpoint of its height) and under
foundation is as follows:
The stress on the soil
directly below the foundation = loads/ foundation area.
The stress on the weak
soil = the load at this level / the area exposed to the load.