In general, shallow pads and strips are the economic foundation for most structures where ground conditions allow this solution.
The suitability of shallow strips and pads should be one of the first considerations for the engineer and their use tends to form the normal foundation criteria against which the extra over cost of abnormal foundations tends to be judged.
This does not mean however, that strips and pads should be used wherever possible since as they become deeper or more heavily reinforced the alternatives of vibrocompaction and/or piles becomes competitive.
However, at shallow depth, they are the economic alternative.
1 Trench fill A brief description of trench fill strips is given previously. The design
of such strips is relatively simple, and it is true to say that there
is more design involved in making the decision to
2 Trench fill design decisions A typical trench fill foundation is shown in Fig. 11.7 where (a)
indicates a typical section, (b) shows the typical design forces, and
(c) illustrates the possible externally applied ground...
3 Sizing of the design In the case of mass concrete trench fill the foundations can be sized
using the assumptions that dispersion of load through the strip can be
assumed to be at an angle of 45°. In the case...
4 Design Example 1: Trench fill strip footing The internal load-bearing wall for a four-storey office block is to be
supported on a strip foundation. Borehole investigations produced the
consistent soil profiles shown in Fig. 11.13.
Soil...
5 Design Example 2: Deep mass concrete pad base A steel-framed building is to be built on a site adjoining previously,
where variable fill extends down to the level of the bedrock. A heavily
loaded stanchion, carrying axial load only, is to be supported on a...
6 Unreinforced concrete strips The unreinforced strip footing requires slightly better ground
conditions than trench fill to maintain trench stability during
construction of the masonry over it.
The adoption of a thin...
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