P3 - Principles of Foundation Design Foundations or substructures need to safely distribute the weight or load of a building into the subsoil. There are four main types of foundation, strip, pad, piled and raft. Soil conditions range from very stable non-cohesive soils to unstable cohesive soils. The choice of foundation depends on the following: The load or weight of the building The load bearing ability of the subsoil The water table Ground Contamination Cost, every site has a limit on cost

P3 - Principles of Foundation Design The Load or Weight of the Building. Most domestic housing can be supported by strip foundations, the depth will vary depending on the ground conditions. Larger commercial buildings tend to use pilings as they can get through layers of soil and get to the load bearing soil. In cases where soil conditions are poor such as loose rubble or made ground pad foundations can be used for larger buildings. Lower and wider building often use a raft foundations as they are spread the load over a wider area.

P3 - Principles of Foundation Design Load Bearing ability of soils Explain the difference between cohesive and non-cohesive soils? Explain which are stronger – sands and gravels or silts and and soft alluvial soils and clays? What is meant by the compressibility of soils? What is made ground? How can made ground be compressed? What is vibro compaction?

P3 - Principles of Foundation Design Explain what settlement is? Explain what to Ground Heave is? Explain what Frost Heave is?

P3 - Principles of Foundation Design Contamination How can ground get contaminated? What is radon gas? How will it affect foundation design?

P3 - Principles of Foundation Design Water Table What is the water table? What will happen in a trial pit if the you go below the water table? What effect can chemicals such as acids and sulphates found in ground water have on foundations? What is pore water pressure?

P3 - Principles of Foundation Design Soil Profiles Do an image search for a soil profile, explain what it is?