Historically there have been many types of materials used to construct pipe and conduits. Some of these include:
- Reinforced concrete
With the advent of modern material science there have been tremendous leaps in developing new materials appropriate for pipes. In particular the broad group of Polymers, elastomers and thermoplastics have been developed whose properties such as heat resistance, strain ratios and roughness can be specifically engineered to suite any project.
At Harris Civil we have developed a preference for High Density ?? polyethylene (HDPE or PE) pipe. It is strong and durable and has enough tensile strength that long lengths can be welded together and installed in one go. Like all materials it is prone to decay. However, unlike most alternatives, it is only prone to decay in the presence of extreme temperature or ultra violet light. This makes it the perfect choice for underground infrastructural installations as high temperature and UV light are virtually not existent at the depths that pipes are installed.
PE also does not require the use of pipe lines which will inevitably experience structural failure over time.
Pipe ramming is a technique similar to pipe bursting. It differs mainly in the materials used and the fact that it is used for new installations instead of replacing existing pipes.
The method uses pneumatic percussive blows to drive the pipe through the ground. The leading edge of the pipe is almost always open, and is typically closed only when smaller pipes are being installed. The shape allows a small overcut (to reduce friction between the pipe and soil and improve load conditions on the pipe), and directs 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 of bentonite and/or polymers can be used (as in horizontal directional boring) for this purpose. Spoil removal from the pipe can be done after the entire pipe is in place (shorter installations). If the pipe containing the spoil becomes too heavy before the installation s complete, the ramming can be interrupted and the pipe cleaned (longer installations). Spoil can be removed by auger, compressed air or water jetting.
Recent research on instrumented pipe ramming installations has allowed the development of pipe ramming-specific models for static soil resistance and dynamic model parameters for simulating drivability of rammed pipes. These procedures can be used to estimate the feasibility of pipe ramming installations.
Range of works
Pipe sizes for pipe ramming is limited on the lower end by pipe slenderness i.e. if the pipe diameter is too small, the pipe will buckle. On the large end it is limited only by power of the machinery and ground conditions. Common sizes installed are: