We can distinguish three main types of foundation which are:
- the surface foundation
- the deep foundation
- the special foundation
Introduction:
A structure, whatever its form and destination, is supported on a seat floor and transmits a set of loads to it.
The elements which play the role of interface between the supporting structure and the ground constitute the foundations .
Adapted to both the structure and the nature of the soil, they take various forms so as to ensure a good distribution of stresses. We distinguish the following different types of foundation :
1-Superficial foundations
- Continuous soles under the wall.
- Insoles insulated under pillars.
- Plots and sills.
2-Foundation by deleting general.
3-Deep foundations.
- On well.
- On stakes.
1- SURFACE FOUNDATIONS:
Shallow foundations (i.e. shallow foundations ) are used when:
- The soil capable of the necessary lift is at depth.
- The shear resistance of the layers is sufficient.
- The deformability of the soil is low.
This process is economical in the case where the bearing soil is accessible by common earthmoving means, that is to say for depths between 1 m and 4 m at most.
The surface foundations consist of footings having a greater width than the supported element so that the compression ratio of the soil does not exceed its admissible compression ratio.
1-1 Continuous footings under the wall:
Wall foundations can be made:
- In masonry.
- In rubble.
- Reinforced concrete.
- Reinforced concrete.
A- Brick foundations:
- At the end of the trench, we lay a first layer of bricks on a layer of coarse sand.
- Over this entire width of the bass we build at least 2 seats.
- We then gradually shrink each set of two seats until the desired thickness or wall is obtained.
- The tangent to the overlaps cannot be tilted by more than 60 ° with respect to the horizontal.
- What exceeds the 60 ° angle undergoes tensile forces: masonry of broques cannot resist it.
B- Rubble foundations:
Rubble foundations generally fill the entire width of the excavation.
- At the bottom of the trench we put a layer of clean concrete.
- Then put a layer of mortar 3 to 4 cm thick and then place the rubble, blocking it and bonding it properly with mortar.
C- Grained concrete foundations:
The cross-section of the groomed concrete foundation in the form of an isosceles trapezoid whose
bass angles are at least 60 °.
Concrete can be cased or poured directly between the two walls of the excavation. It must be of “wet earth” consistency and carefully groomed during installation.
This concrete is sometimes lightly reinforced to form a chain which may be necessary if the soil is not homogeneous.
D- Reinforced concrete foundations:
We use reinforced concrete footings :
- To distribute the load more evenly (consequence of their greater rigidity).
- To limit the weight of foundations ( stronger foundations therefore less thick).
- To reduce the pressure exerted on the ground by widening the sole (which requires a reinforcement to resist the tensile forces produced at the bottom of the sole ).
First, a lean concrete of conc