Microtunneling is a trenchless technology which combines a remote controlled, steerable boring machine with pipe jacking technique to install product pipelines underneath the ground in a single pass. Microtunneling with pipe jacking (MTBMs) is usually adopted for diameters from 200mm with Vacuum Microtunneling to 3000mm with Slurry Microtunneling.
MTBMs were initially developed in Japan in early 1980s for gravity sewer pipe installation and as such can be steered to ensure the correct line and grade of the sewer line. Since then, they have been used to install several product pipelines other than sewer in conditions where any other trenchless technology in the world would fail. This flexibility is due to availability of a range of cutter heads which can be used with MTBMs depending on soil / rock conditions and ground water level. We have executed several hydrocarbon river crossing and sewerage projects in the last more than 10 years by Microtunneling method.
We offer complete EPC service for your projects including –
- Project planning – Site investigation and design calculations
- Selection of right equipment and cutter head as per the ground conditions
- Structural designing of launch / receive shafts and jacking pipes
- Construction of launch / receive shafts
- Pipe Supply (RCC with or without HDPE lining, GRP, Steel, etc)
- Quality control
And all this while maintaining international safety standards and with minimal effect to surrounding environment.
Although Microtunneling is one of the most complex installation techniques in the world, still it becomes indispensable in the following conditions –
- Installation of large diameter deep gravity sewers (with requirement of high precision) in cities where open cut installation is not an option owing to existing surface establishments.Maximum deviation from the target position for installation of gravity sewer pipes –These deviations are within the permitted tolerances as specified by the norms.
- Installation of product pipelines in areas where soil condition is such that a HDD annulus bore cannot be stabilized. There is almost no such soil / rock condition where MTBMs cannot be used. E.g., Installation of casing pipes for hydrocarbon carrier lines in gravel laden ground.
- Long crossings across rivers. For longer pushing lengths, intermediate shafts and several interjack stations can be used at pre-defined intervals to reduce pressure required in launch shaft jacking station. E.g., Teesta River crossing for Oil India Limited’s pipeline installation project.Depending on geology, following individual length crossings are possible
|ID (in mm)||Individual Crossing Length (in m)|
|600 – 800||Up to 150|
|800 – 1,000||Up to 250|
|1,000 – 1,500||Up to 500|
|> 1,500||Up to 1,200|
- Using modern surveying techniques, it is possible to microtunnel around bends. This removes the straight line restriction present in other trenchless technologies.
- Installation of pipelines that end in rivers, sea, etc. Outfall is done by removing the supply lines for the cutter head once the drilling the complete and then removing the head using a floating crane.
- Because of its minimal effect on the surroundings, MTBMs can be safely used in environmentally sensitive areas.
- Since most of the operation is remote controlled from a control cabin safely located above the ground, Microtunneling is one of the safest trenchless operations where such large diameters are involved. At the same time, it allows construction in all weather conditions.