The installation process and methods of sheet pile foundations are equally important factors as of the design process. Sheet pile foundation installation methods are by sheet pile hammer and boring by mechanical auger.
To avoid damages to the sheet piles, during design, installation Methods and installation equipment should be carefully selected.
If installation is to be carried out using sheet pile-hammer, then the following factors should be taken in to consideration:
- • Size and the weight of the sheet pile
- • Driving resistance which has to be overcome to achieve the design penetration
- • Available space and headroom on the site
- • Availability of cranes and
- • Noise restrictions which may be in force in the locality.
Sheet Pile Driving Methods (Displacement sheet piles)
Methods of sheet pile driving can be categorised as follows:
- • Dropping weight
- • Explosion
- • Vibration
- • Jacking (restricted to micro-piling)
- • Jetting
Drop Hammer Method of Sheet Pile Driving
A hammer with approximately the weight of the sheet pile is raised a suitable height in a guide and released to strike the sheet pile head. This is a simple form of hammer used in conjunction with light frames and test piling, where it may be uneconomical to bring a steam boiler or compressor on to a site to drive very limited number of sheet piles.
There are two main types of drop hammers:
- • Single-acting steam or compressed-air hammers
- • Double-acting sheet pile hammers
Single-acting steam or compressed-air comprise a massive weight in the form of a cylinder. Steam or compressed air admitted to the cylinder raises it up the fixed piston rod. At the top of the stroke, or at a lesser height which can be controlled by the operator, the steam is cut off and the cylinder falls freely on the sheet pile helmet.
Double-acting sheet pile hammers can be driven by steam or compressed air. A piling frame is not required with this type of hammer which can be attached to the top of the sheet pile by leg-guides, the sheet pile being guided by a timber framework.
When used with a sheet pile frame, back guides are bolted to the hammer to engage with leaders, and only short leg-guides are used to prevent the hammer from moving relatively to the top of the sheet pile. Double-acting hammers are used mainly for sheet pile driving.
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