What is Pipe Jacking: types, uses, benefits
How to install pipes without tearing up the road above? The answer relies on such a magnificent process called “Pipe Jacking”. Pipe jacking is a way to push pre-made pipes through the ground from a launch pit to a reception pit without digging a trench. It uses hydraulic jacks. While a cutting head clears soil and keeps the line and grade, crews add pipe sections one at a time. But what makes it popular in piping systems? In crowded cities where heavy traffic requires low-downtime projects, Pipe jacking comes to the ring!
Pipe jacking is a trenchless method that forces pre-fabricated pipes into the ground by transmitting from a launch pit to another one with no need for trenching. This Method mainly uses hydraulic jacks to move pipes, and a cutting head cleans the way. Also, expert workers add pipes in sections.
Let’s break it down to various types of pipe jacking, how the material selection influences the process, and use cases of pipe jacking in both GRP and steel pipelines.
Types of Pipe Jacking: When to Use Each?
There are three main types of pipe jacking: conventional, microtunneling, and auger boring. You can choose these methods based on what the project needs.
Conventional Pipe Jacking
In the traditional setup, a thrust wall and hydraulic jacks in a launch pit push pipes that have already been made toward a reception shaft. This shaft is usually behind a shield or cutting face that controls the digging.
Where Do People Use The Traditional Pipe Jacking Method?
It works well on medium- to large-diameter pipes that are straight and may see some slope as well.
How To Deal With Spoilage or Control Friction in Traditional Pipe Jacking?
Crews use conveyor belts, muck cars, or excavators to get rid of spoil at the face when the ground is stable or mixed. They use annular lubrication (usually bentonite) to control friction and keep jacking forces within design limits.
Intermediate jacking stations are placed between pipe strings to spread out the thrust and protect the joints when the drive is longer or there is more overburden.
Quality control: Always check the joint gaps with each push and compare the jacking force logs to the expected friction curves. We also watch the surface settlement around the shafts and along the alignment.
Microtunneling (Pipe Jacking with a Remote Control)
Microtunneling uses a remotely controlled MTBM at the front of the pipe string. This setup gives you active face support and laser guidance to help you keep the line and grade just right. (Source: ScienceDirect) It works best in places with a lot of groundwater or areas that contain a heavy load of sewage.
- Spoil Removal & Soil Stability: The dirt that has been dug up is moved by a screw conveyor or a slurry circuit. This keeps the face stable and makes it less likely to settle in soft soils.
- Handling Longer Drives & Curves: This Method lets you drive for longer and make turns more easily, but it takes more work to set up. This includes a plant that separates slurries and a strong shaft design.
- Real-Time Monitoring of Alignment: Operators always check alignment with laser target readings, and they write down any steering corrections as they happen. Jacking loads affect both the rate of lubrication and how the soil behaves.
- Safety Considerations: The outcome is safer operation, with no people inside the bore, and repeatable accuracy, which is essential when there isn’t much room for error and no time to waste.
Jack-and-Bore Hybrid: Pipe Jacking and Auger Boring
The casing pushes forward while a rotating auger inside it digs up dirt and sends it back to the launch shaft. This Method is easy, fast, and works best for short, straight crossings under roads or rail beds.
Consideration for the Jack-and-Bore Hybrid Method
- Best Soil Conditions: It works best in some sands and good clays. California Department of Transportation highlights that Cobblestones and boulders can mess up the auger and make it less well-structured.
- Pilot-Tube System for Precision: Before using the auger to make it bigger, you can use a pilot-tube system to create a guided path. But this method still works best when the lines are straight and the grades are small.
- Use of Casing: After the breakthrough, the installed casing is often used to hold a carrier pipe that is pushed or pulled through.
Quality Control
QA checks to make sure the setup is correct, the bore is aligned with the shaft, and the torque and advance are very close to each other.
Which Method Meets Your Project Requirement?
Tight line-and-grade under urban constraints suggests microtunneling; large diameters with workable access suggest conventional jacking; and very short, straight utility crossings often work best with jack-and-bore.
| Project Conditions | Best Pipe Jacking Method | Ideal For |
|---|---|---|
| Urban environments with tight line-and-grade | Microtunneling | Installing gravity sewers in crowded urban areas with high groundwater. |
| Large diameter pipes with accessible shafts | Conventional Jacking | Larger diameter pipes in areas with good access for launch and reception pits. |
| Short, straight utility crossings under roads/rail | Jack-and-Bore | Quick, efficient installation for short, straight utility crossings under infrastructure. |
Effective Components in Pipe material Selection of Pipe Jacking
After selecting the proper method for pipe jacking, it’s time to consider some crucial factors that influence the following process. Let’s figure out how mechanical strength, pipe weight, diameter size, or overall cost changes the decision in pipe selection.
Mechanical Strength: Pressure Tolerance
The mechanical strength of pipes plays a vital role due to their resistance against soil pressure and further loads of installation, and while in use.
- Steel and Concrete: Materials like steel or concrete can mainly resist heavy loads, but corrosion can cause trouble.
- GRP/GRE: Unlike previous materials, GRP/GRE pipes, with their plastic nature, have a high strength-to-weight ratio and can withstand moderate to high-pressure soils.
Pipe Weight
Pipe jacking requires a jacking force that a light pipe can decrease, thereby reducing the need for these forces and easing the installation and transportation.
Which Pipe is the best?! GRP pipes are lighter than steel and concrete, which includes less strain on the system, while concrete is a heavier case, making the installation process more intensive and requiring heavy machinery for transportation.
Diameter Size and Wall Thickness
The diameter and thickness of pipes must meet certain specs to handle specific pressure. In large diameters, concrete can be used, though they are heavier.
GRP pipes are created in the same strength but with thinner walls, which makes them superior in terms of cost, space, and weight.
Consideration: Thicker walls are mainly able to handle heavy external pressure, which is such an essential property in deep installations.
Overall Cost: Cheap or Efficient?
Although concrete pipes are cheaper in terms of material cost, they require larger machineries for transportation and installation, which increase the final costs.
While GRP pipes may include higher initial costs, due to their lightweight, they may reduce the overall cost of the installation process. They also have lower maintenance and repair costs.
Durability Against Corrosion and Chemicals
In sewage and industrial environments, the corrosive nature requires resistant pipelines; GRP/GRE pipes include high resistance to corrosion and chemicals. (Source: Scribd) Concrete pipes need coatings and linings to withstand such conditions.
Comparison of Common Materials in Pipe Jacking
After you recognize the effective factors for pipe selection in the pipe jacking system, it’s time to weigh them through various pipe types and compare pipes to find the most proper choice.
- Concrete Pipes: They are thick and heavy, which makes them perfect for high-pressure projects, but they are cost-intensive during installation. Due to their heavy nature, concrete pipes require stronger hydraulic jacks. Though they are durable, some failure may occur in corrosive conditions.
- Steel Pipes: They are such heavy pipes that can withstand heavy loads. However, they include high material costs and extra coatings for corrosion resistance in underground installations.
A Quick Pause: Steel or Concrete?
While steel can be used for decades, its coating requirement and higher weight make it less affordable than concrete in specific projects.
- Clay Pipes: according to CPDA, they’re less common in today’s uses due to their limitation in size and resistance. Although they are corrosion resistant, limited diameter sizes make them less popular in modern trenchless pipelines.
- GRP/GRE Pipes: These pipes surpass other pipes due to their lightweight and high mechanical strength. Though they include high initial costs, they win the game by overall cost in larger projects that last decades.
Here’s a comparison table of these pipes. Track them to choose the best!
| Property | Concrete Pipes | Steel Pipes | GRP/GRE Pipes |
|---|---|---|---|
| Thickness | Thick (necessary for strength) | Moderate (higher strength at thinner walls) | Thinner than concrete and steel |
| Strength | High compressive strength | High tensile and compressive strength | High strength, resistant to soil pressure and loads |
| Weight | Heavy | Heavy (requires heavier jacks) | Lighter, easier to handle and install |
| Approx. Cost | Low material cost, high transportation and installation cost | High material cost, additional coating costs | Moderate material cost, lower transportation and installation costs |
| Durability | Susceptible to corrosion unless coated | Prone to corrosion without protection | Corrosion-resistant, ideal for aggressive environments |
- Final Touch: GRP/GRE pipes are superior due to their lightweight and corrosion resistance. Also, they reduce the cost of installation and further maintenance in sewer and industrial fluid transmission.
Applications of Pipe Jacking with GRP/GRE Pipes
As we clarified how pipe jacking influences installation, in this section, we’ll provide a comprehensive guide to its unique use cases, such as in urban sewer networks, oil and gas projects, and hard-to-dig places.
- Urban Sewer Networks: GRP/GRE pipes are great for sewer transmission in large cities where lightweight and corrosion-free pipes that reduce the downtime in traffic zones are required.
- Water Transmission Lines: These pipes play a powerful role in water pipelines in crossing roads and railways due to their flexibility and high strength-to-weight ratio.
- Oil And Gas Projects: GRP/GRE pipes are mainly used in oil and gas pipelines due to their perfect resistance in harsh environments and fire retardance. They have a lower need for maintenance compared to alternatives, making them top choices in aggressive conditions.
- Area With Limited Open Excavation: Last but not least, GRP pipes include such an opportunity for sensitive places that are hard to dig, like historical sites or traffic zones, to keep the downtime in the lowest mode.
Final Wrap-Up
Pipe jacking is a modern solution to pipe installation in trenchless methods. As we discussed, the proper selection of pipelines eases the process and decreases costs and probable dilemmas during the installation. GRP/GRE pipes are a reliable choice for pipe jacking due to their perfect performance in corrosive and high-pressure areas.
Get in touch with our consultants for beneficial advice on underground pipe jacking installation and how it can align with your project demands!
Frequently Asked Questions
1- Where is Conventional Pipe Jacking used?
Conventional pipe jacking is used for medium- to large-diameter drives that are straight or slightly sloped.
2- What are the best conditions for Microtunneling?
It works best in places with a lot of groundwater or places that contain a heavy load of sewage.
3- Why are GRP/GRE pipes superior to concrete and steel?
GRP/GRE pipes are corrosion-resistant, lighter, and cost-effective, reducing installation and maintenance costs. They are ideal for sewer and industrial fluid transmission.
4- How does pipe weight impact Pipe Jacking?
Light pipes reduce the need for jacking force and ease the installation and transportation process. GRP pipes are lighter than steel and concrete, while concrete is heavier and requires heavy machinery for installation.
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