Have you ever wondered how underground installations take place without disturbing the surface infrastructure or landscape? The answer lies within trenchless technology. There are many types of trenchless methods for the installation of underground utilities, ranging from horizontal directional drilling to pilot boring. However, auger boring is one application proven to be more cost- and time-efficient. This procedure-mode has been in operation since the 1950s, and with technological advancements it has become even more sophisticated, helping contractors perform more challenging, and accurately-driven bores.
What is Auger Boring?
Auger boring is a trenchless construction method that creates horizontal boring by jacking the steel casing through the earth from a main shaft to a reception shaft. The process uses a rotating helical auger to excavate material from the bore hole through the casing pipe and transfer it to the main shaft for removal. An Auger Boring machine bores through soil or rock with a cutting head attached to the lead auger to install steel casing pipes, utilities, and other underground structures.
Benefits of Auger Boring
- This boring process significantly reduces surface disturbance compared to other traditional open-cut methods. The minimal footprint makes it an ideal choice for urban areas and environmentally sensitive places.
- The reduced usage of excavation and restoration materials, labour and traffic management helps in lowering the overall project costs.
- It adopts a streamlined process, which allows for faster installation of underground utilities, reducing the project duration.
- This method can be the best fit for any soil conditions and bore lengths, making them a versatile boring solution for any location.
- It uses fewer excavation and soil disposal activities, without affecting the carbon emission norms, mitigating the environmental impacts.
Applications of Auger Boring
Pipeline Installation
Auger boring is used for various pipeline installations beneath roads and infrastructure without extensive excavation and minimising surface disruption.
Tunneling for Utilities
They help in installing underground utilities like telecommunication lines, electric cables, and fiber-optic cables, especially in urban areas.
Geotechnical Investigations
This process is also used to collect soil samples to assess the subsurface condition of the construction projects, and to determine the type of foundation that needs to be installed.
Auger Boring Process: Step-by-Step
Step 1: Preparation
The first step in the auger boring process is the meticulous planning, where the soil composition, geological conditions, and underground utilities are assessed. Based on the analysis, appropriate planning is made to ensure smooth execution and minimise the risk and complications.
Step 2: Setup
A launch pit and a receiving pit are excavated at opposite ends of the area where the bore needs to be excavated. The launch pit acts as the starting point for the auger, while the receiving pit facilitates the extraction of excavated soil and installation of the casing pipe.
Step 3: Auger Drilling
A horizontal drilling rig equipped with an auger assembly is installed at the launch pit. Where the auger that is driven by hydraulic motors, rotates and penetrates the ground gradually, by creating a horizontal bore path. As the auger progresses into the ground, it excavates soil and transfers it back to the surface of the soil for disposal.
Step 4: Casing Installation
While the drilling process progresses, a casing pipe made of steel is pushed into the freshly drilled hole. This casing does multi-tasking by maintaining the integrity of the bore, preventing the ground from collapsing and providing a conduit for the installation of utility lines.
Step 5: Product Installation
Once the casing is installed, utility lines, such as water mains, sewer pipes or other utility pipes or cables, can be inserted and installed within the underground infrastructure, using the casing.
Step 6: Extraction
After completing the bore, the auger is reversed and retracted back to the launch pit. During this time, the casing pipe remains in position, acting as a protective sleeve for the utilities installed.
Step 7: Backfilling and Restoration
The excavated pits are finally backfilled and the surface is restored to its original condition, minimizing the disruption of the environment.
Auger Boring Equipment and Components
- Auger Boring Machine is the main equipment that is used to drive auger and casing through the ground, providing the necessary power and control.
- Pilot Auger is a small auger used to drill the initial pilot hole, and act as a guide for larger casing.
- Steel Casing is a strong and durable casing pushed into the search as the earth excavates soil. It helps maintain structural integrity and offers a passageway for utility installation.
- Hydraulic Jacks pushed the steel casing and auger forward through the soil, applying high pressure for gradual progress.
- Pilot Tubes are small tubes used to guide the pilot auger, ensuring precision and alignment of the bore.
- Spoil Removal Shaft is a shaft that carries the excavated material back to the entry shaft, and helps maintain the efficiency throughout the boring process.
- Cutting Head is a rotating head at the front of the auger, that breaks the soil and rock into pieces and helps advance through the earth.
Challenges and Limitations of Auger Boring
- In places of hard or rocky soil conditions, this boring method can be difficult to penetrate, where additional equipment or alternate techniques are used.
- The bore length and diameter are limited based on the capabilities of the auger equipment, thus requiring careful planning and feasibility, especially for large-scale projects.
- Without meticulous planning, there are chances of unforeseen conflicts with the existing underground utilities, affecting the bore path or alternative installation methods.
- Geological features such as groundwater, underground cavities, or sensitive environmental areas can be an obstacle to the auger boring process. In such cases, specialised solutions and mitigation measures should be considered.
- In congested areas or restricted space, setting up the auger boring equipment can be a big challenge.
Conclusion
In summary, auger boring is a trenchless, efficient means of installation of underground utilities with little inconvenience within the area affected directly or indirectly. This method has the advantage of being precise, cost-effective, and eco-friendly with the use of special types of equipment for various applications like the installation of pipelines and geotechnical investigation purposes. As infrastructure needs increase, auger boring is still an important technique in modern construction.