A pipe mole, also known as a soil displacement hammer or groundhog, works by pneumatically displacing soil to create a bore for installing new underground pipes or services without open trenching.
Here's a breakdown of the process:
- Soil Displacement: The mole uses a percussive hammer action, driven by compressed air, to drive itself horizontally through the soil.
- Bore Creation: As the mole advances, it compacts and displaces the soil around it, creating a cylindrical bore. The mole doesn't remove the soil; instead, it pushes it aside.
- Pipe Installation: Once the mole reaches the target destination, the new pipe or service is typically pulled through the newly created bore. This is often done by attaching the pipe to the rear of the mole before the mole begins its journey.
Here's a more detailed view:
- Setup: The mole is placed in a launch pit or trench, aligned with the desired path for the pipe.
- Operation: Compressed air is supplied to the mole, powering its internal hammer. The operator guides the mole using aiming sights and monitors its progress.
- Ground Conditions: The effectiveness of a pipe mole depends heavily on the type of soil. They work best in displaceable soils such as clay, silt, and loam. Rocky soil or very loose sandy soil can hinder or prevent its operation.
- Distance and Diameter: Pipe moles are typically used for relatively short distances, up to around 20 meters in ideal conditions, and for pipe sizes ranging from 25mm to 150mm.
- Accuracy: While moles can be steered to some extent, their accuracy can be affected by soil conditions. It's important to consider the ground conditions before use.
- Benefits: The method offers several advantages, including reduced excavation, minimal surface disruption, lower costs, and faster installation compared to traditional trenching methods.
In summary, a pipe mole efficiently creates a tunnel under the ground by displacing the soil using compressed air and a percussive hammering action, enabling the installation of pipes without extensive excavation.
