Marshalls CPM offer a range of reinforced precast concrete manhole units specially designed for sinking by the caisson method from 2000mm diameter to 4000mm internal diameter in varying depths (please see table below).
This is achieved by using a shaft sinking plate system and is made in accordance to BS EN 1917:2002 and kitemarked where relevant to BS 5911-3:2010.
Advantages of the systems include:
Suited to weak soils, high-plasticility clays, silts, sands and gravel
Minimal site labour costs
Quick and easy to install
Fast, clean accurate construction
Immediate permanent shafts
Suitable for jacking pits
The caisson shaft sinking system was originally designed for use in microtunnelling, but is now more widely used for construction of pumping stations, wet wells and manholes, particularly in difficult ground conditions.
Caisson chamber section weights and dimensions notes:
4000mm chambers are supplied in two half sections, each weighing approximately 3180 kg per metre, for assembly on site.
The steel cutting shoes are fitted to the base section providing a 10mm overbreak on all except 3660mm and 4000mm which provide a 20mm overbreak.
Cutting shoes with a larger overbreak can be manufactured upon request.
+ Non-kitemarked
Weights are based upon 675 x 675 opening or similar