What is raft foundation preferred?
a) Raft foundations are preferred in areas with poor soil bearing capacity, uneven settlement, and the presence of mixed soil types. These foundations achieves the load-bearing capacity through the distribution of stresses to a larger area.
What is foundation spread?
Spread foundations are foundations at shallow depths of burial where the ground resistance on the sides of the foundation does not contribute significantly to the bearing resistance. Some of the provisions in this Section may also apply to deep foundations, such as caissons and piers [C6.
What is the minimum depth of raft foundation?
The minimum thickness of raft foundation is 300mm.
What are the three types of raft foundation?
There are five main types of raft foundation:
- Solid slab rafts,
- Slab beam rafts,
- Cellular rafts,
- Piled raft foundations; and,
- Balancing (or floating) rafts.
What are the 3 purposes of foundation?
The three most important are to bear the load of the building, anchor it against natural forces such as earthquakes, and to isolate it from ground moisture. The relative importance of these functions changes with the type of land underneath the building and the building design.
What are the main requirements of foundation?
What are the Requirements of a Good Foundation?
- Permanence. It’s essential for foundations (and the building itself) to be placed in an area in such a way that it will not be affected by future construction work or projects. …
- Stability and Cohesion. …
- Depth. …
What are the causes of foundation movement?
Foundation movement is caused by changing soil conditions, hydrostatic pressure, structural instability of footers or piers, invasive tree roots and poor exterior drainage management. Earthquakes, floods and frost heave also can contribute to soil shifts and foundation movement.