Pallett, Peter F and Filip, RayISBN 978-0-7277-6338-9https://doi.org/10.1680/twse.63389ICE Publishing: All rights reserved

g Water treatment: purification plant for clean water, sewage treatment plant for

wastewater.g Communications: overhead cables, satellite receiver dish, aerial mast.g Transport links: roadway, airstrip, harbour with quayside, helipad, railway siding,

canal.

3.3. Communications, energy, clean water supply andwastewater disposal

3.3.1 CommunicationsIt is common business practice to provide high-speed internet access on site for all site-

based personnel. Advances in technology for mobile devices means we now only need a

single lightweight hand-held device that can be used as both a laptop and mobile phone.

Figure 3.2 Compound layout for a small site. (Courtesy of Costain)

Position of compoundand high value storage area70 m × 40 m

18 × 11 m × 1.8 mClose board timber fencing

2.4 m Chainlink fencing

2.4 m Chainlink fencing

Position of work areaand fuel storage110 m × 180 m

3 No. 6 mdouble leaf gates

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1 No. pedestrianaccess gate

Site compounds and set-up

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Case study 1

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(Figure 4.6). The foundation designer will design the foundation for the imposed loads to

prevent bearing-capacity failure, overturning, sliding or structural failure. If the loads are

relatively low and the soil is relatively strong, the foundation can be designed as ground

bearing. However, these bases can be large: 6 m × 6 m in plan and at least 1.5 m depth

is not uncommon. Due to the depth of the foundation care should be taken when excavat-

ing to prevent ground collapse, especially in poor ground. It is often of economic benefit to

Figure 4.4 Typical cruciform base on rails. (Courtesy of RKF Consult Ltd)

Concrete ballast providedby crane supplier

Section (NTS)

Reinforced concrete foundation –could also be piled for poor ground

Steel cruciform with bogies

Crane mast

Figure 4.5 Diagrams of typical expendable base arrangements. (Courtesy of RKF Consult Ltd)

Tower crane bases

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Case study 2

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to apply (because these support systems are relatively flexible and there is a degree of soil

arching and displacement which leads to a redistribution of pressures). From full-scale

tests, Terzaghi and Peck (1996) derived empirical trapezoidal pressure diagrams for

calculating maximum strut loads. From further experience, these pressure diagrams were

Figure 12.5 (a) Post and plank excavation and (b) side rail system trench. (Courtesy of GroundforceShorco Ltd)

Trenching

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Case study 3

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It is also essential that the site team understands the limitations of the plant use on the

barge or pontoon, and does not stray outside of the boundaries set. Any required

changes to site operations should be referred back to the designer to confirm it is safe

to proceed.

As well as cranes, excavators can also be used on barges for such activities as dredging or

grading of river banks or for positioning of bank protection such as rip rap (large

stonework). An excavator working is more dynamic than a crane and the pontoon can

experience more roll, which can make working difficult. In these circumstances, the

barge may be fitted with ‘spud legs’, which are generally circular tubes running through

the deck of the pontoon. These can be lowered so they embed into the river bed to

provide extra stability (Figure 18.2).

Care does need to be taken when using spud legs purely for stability if the watercourse is

subject to wave action or the pontoon is operating during an ebb tide. The reason for this

is that in either scenario an air gap could appear below the pontoon, meaning its weight

is transferred onto the spud legs rather than being supported by the water. If the pontoon

has not been designed for this scenario it could either become unstable or individual

elements could fail due to the change in load path.

If any of the above scenarios could occur a jack-up barge may be more appropriate (see

Section 18.2.3).

Figure 18.1 Typical barge with crane and ancillary plant

Floating plant

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Case study 4

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Screens can be clad in either solid panels (e.g. plywood) or perforated mesh or netting,

and are supported on rails attached to the already cast slabs of the permanent structure.

Commonly, perforated panels or mesh is chosen as it provides a balance between

reducing the imposed wind load, while protecting those below who may be struck by

falling debris, but still permitting natural light to enter each working level. Screens can

incorporate working platforms for essential work such as post-tensioning operations or

to provide space for following trades undertaking work on the facade. Some screens are

simple barriers without platforms, but do have folding covers to prevent debris falling to

lower levels.

25.5.3 Design considerationsSimilar criteria to those examined when determining the suitability of a climbing form-

work system are applicable when deciding on the suitability of a protection screen

Figure 25.7 Typical protection screen sections. (Courtesy of Hunnebeck (a BrandSafway company))

Three platforms(2 deep + 1 wide)

Single cantilever

Four platforms(3 deep + 1 wide)

Single cantilever

Four platforms(2 deep + 2 wide)

Double cantilever

Dry Dry Dry

Dry Dry Dry

Wet Wet Dry

Wet Wet

Climbing and slip forms

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Case study 5

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