- Pipe ramming
Pipe ramming is a
trenchless method for installation of steel pipes and casings over distances usually up to 30m (150 ft) up long and up to 1,500mm (60-inches) in diameter, although the method can be used for much longer and larger installations. The method is the most useful for shallow installations under railway lines and roads, where other trenchless methods could cause surface settlement or heaving. The majority of installations arehorizontal, although the method can be applied for vertical installations as well.The method is pneumatic, i.e. it uses pneumatic percussive blows to drive the pipe into the ground. The leading edge of the pipe is almost always open, and is typically closed only when smaller pipes are being installed. Its shape has to allow a small overcut (to reduce friction between the pipe and soil and improve load conditions on the pipe) and to direct the soil into the pipe interior instead of compacting it outside the pipe. These objectives are usually achieved by attaching a soil-cutting shoe or special bands to the pipe.Further reduction of friction is typically achieved with lubrication, and different types ofbentonite and/orpolymers can be used (as in horizontaldirectional boring ) for this purpose. Spoil removal from the pipe can be done after the whole pipe is in the ground (shorter installations), or, if the pipe with the spoil becomes too heavy before the installation is completed, the ramming can be interrupted and the pipe cleaned (longer installations). Spoil can be removed by auger, compressed air or water jetting.References
* http://www.ttc.latech.edu/publications/guidelines_pb_im_pr/ramming.pdf
External links
* [http://www.hammerheadmole.com/methods/pipe_ramming_method.htm Pipe Ramming]
* [http://www.tt-uk.co.uk/s5-grundoram-pipe-laying-and-renewal-systems.html How Pipe Ramming Works]
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