Q.
Using sketches, show the types of shallow foundation and describe the soil conditions and types of building structures where it is specifically used.
(15 marks, 2012 Q1b)
A.
Similar question was asked in Part 2 2012 Q1.
Wikipedia has a somewhat different terminology for Shallow Foundation from what is used by University of West England, largely verbatim here.
From Wikipedia:
Contents
Spread footing foundation
Mat-slab foundations
Slab-on-Grade foundation
Rubble trench foundation
Earthbag foundation
Screwpiles
See also
External links
From The Constructor: here
From University of West England:
Shallow foundations (sometimes called 'spread footings') include pads ('isolated footings'), strip footings and rafts.
Shallow foundations are those founded near to the finished ground surface; generally where the founding depth (Df) is less than the width of the footing and less than 3m. These are not strict rules, but merely guidelines: basically, if surface loading or other surface conditions will affect the bearing capacity of a foundation it is 'shallow'. Shallow foundations (sometimes called 'spread footings') include pads ('isolated footings'), strip footings and rafts.
Shallows foundations are used when surface soils are sufficiently strong and stiff to support the imposed loads; they are generally unsuitable in weak or highly compressible soils, such as poorly-compacted fill, peat, recent lacustrine and alluvial deposits, etc.
Pad foundations
Pad foundations are used to support an individual point load such as that due to a structural column. They may be circular, square or reactangular. They usually consist of a block or slab of uniform thickness, but they may be stepped or haunched if they are required to spread the load from a heavy column. Pad foundations are usually shallow, but deep pad foundations can also be used.
Strip foundations
Strip foundations are used to support a line of loads, either due to a load-bearing wall, or if a line of columns need supporting where column positions are so close that individual pad foundations would be inappropriate.
Raft foundations
Raft foundations are used to spread the load from a structure over a large area, normally the entire area of the structure. They are used when column loads or other structural loads are close together and individual pad foundations would interact.
A raft foundation normally consists of a concrete slab which extends over the entire loaded area. It may be stiffened by ribs or beams incorporated into the foundation.
Raft foundations have the advantage of reducing differential settlements as the concrete slab resists differential movements between loading positions. They are often needed on soft or loose soils with low bearing capacity as they can spread the loads over a larger area.
Piled raft foundation of a power plant in Rotterdam below:
Ref:
http://environment.uwe.ac.uk/geocal/foundations/Fountype.htm