Most candidates were able to:
- list the levels that may be transferred from a site datum in substructural work;
- state the factors influencing the choice of foundation type.
However, they were unable to:
- sketch the cross-section through an excavation in a moderately firm soil correctly;
- state the reasons for placing foundation below finished ground level.
The expected response to question 1 is as given below:
(a) (i) the top of hardcore bed
(ii) bottom of pit excavation
(iii) bottom of trench excavation
(iv) top of concrete foundation
- top of oversite concrete
- bottom of drain trench
- finished ground level.
(b)
Three factors that influence the choice of a foundation type:
- nature and bearing capacity of soil;
- the depth where suitable load-bearing soil would be found;
- water table;
- the distance from trees which can affect the stability of the soil;
- the total weight of the building.
Reasons for placing foundation below ground level:
- climatic factor;
- effects of erosion;
- presence of roots.
