What is Pipe Ramming?
Pipe ramming is a trenchless method for installation of steel pipes or casings, in which a pneumatic tool is used to hammer the pipe or the casing into the ground.
Pipe ramming is ideal for trenchless installation under railway and road embankments. When casings are installed, pipes of other types for distribution of sewerage, water or gas, or electrical or telecommunication cables are subsequently inserted.
Pipe ramming is most valuable for installing larger pipes over shorter distances and for installations at shallower depths.
It is suitable for all ground conditions except solid rock, and is the safest method compared other trenchless methods that can lead to unacceptable surface settling.
Since no ground is removed until after the casing is installed the risk of subsidence is eliminated.
How does Pipe Ramming Work?
In a pipe ramming operation, a ramming tool attached to the rear of a steel pipe drives the pipe into the ground with repeated percussive blows.
The method typically requires excavation of two pits.
Before ramming, both the pipe and the ramming tool are placed into the insertion pit and lined up in the desired direction.
Alternatively, the ramming can be launched without an insertion pit, if the ram is designed to start at the side of a slope. In contrast to pipe jacking, thrust plates or blocks in the insertion pit are not required.
The installed pipe usually has an open end that allows the soil to enter the pipe during the installation. The spoils inside the pipe can be removed either during or after the installation, by auger, compressed air or water jetting. The installed pipe can also have a closed end, but this option is usually selected only for installation of small diameter pipes or specific ground conditions.
After completing the installation, the pipe is ready for use or other pipes or cables can be inserted through it.
What are some of the applications of pipe ramming?
Trenchless installation of services under structures:
Casings can be installed under highways and railway tracks without interrupting traffic or rail operations. The casings can then be used as culverts or sliplined with product pipe such as telecommunications, gas, water, or sewer pipes.
Renewal of cuvlerts:
Existing culverts can be replaced without open cut. The pipe rammer installs a steel casing around the outside of the existing culvert. The existing deteriorated culvert is then removed and a new culvert installed inside the casing.
Another option is sliplining existing culverts. The pipe rammer is used to pull new product pipe through the existing deteriorated culvert.
Underpass installation:
Large diameter pipes up to 4.0m diameter can be installed by pipe ramming method to create an underpass under an existing railway line or roadway.
Tunnel Canopy Installation:
One use of pipe ramming is the installation of steel pipes to form a roof support for tunnel construction beneath existing infrastructure such as railroad tracks, highways etc.
Horizontal directional drilling assist:
In addition to new installations, pipe ramming can be combined with directional drilling and used to free the product pipe during pullback (or the drill pipe during pilot hole boring or reaming) if it gets stuck due to hydrolock or differential pressure sticking. The ramming tool is attached to the end of the product pipe when pullback slows down or stops, and the percussive action of the rammer helps to keep pipe moving through a difficult section.
Pile driving:
Pipe ramming is typically used for horizontal installations, but can also be applied for vertical projects, such as piling driving or micro-piling. An example of vertical application is an installation of vertical supporting piles from a bridge through a body of water, when the bridge cannot support the weight of a crane necessary in a traditional method of installation of such piles.
Pipe Ramming is a cost effective alternative for installing steel casings under roads, rail lines, structures and finished landscapes. This technique can be used in all soil conditions up to weak rock. It is perfect for flowing soil or ground with a high cobble content.
Pipe ramming does not remove any soil until the casing has been installed full length. This eliminates the risk of subsidence. After the casing has been installed the soil is removed and the service installed in the steel casing. The annulus is then grouted to hold the service in place.
