Geonex Horizontal Hammer Boring provides a practical alternative for challenging ground where conventional trenchless methods struggle—without fluid support or thrust walls.
The Challenge of Hard and Mixed Geology
HDD market is growing, and greater lengths and diameters are achieved continuously. One thing, remaining as a great challenge, is the risk of bentonite frac-out. Usually when sufficient cover depth is achieved, the risk becomes significantly smaller. Another challenge can be the surface soil conditions, which may vary a lot and be inconsistent. These challenges may cause scheduling, economic and environmental problems. Achieving this sufficient cover depth and homogenous soil conditions reliably and safely, would ease HDD contractor’s life.
How Geonex HHB Helps
For HDD, Geonex HHB (Horizontal Hammer Boring) can offer significant benefits since conductor barrels for HDD can be drilled to reach solid bedrock or other desired cover depth. This enables safe and stabile starting for actual HDD drilling ensuring the return of the drilling fluids. Unstable inconsistent soil formations are often difficult to support with drilling fluids and steel casing offers a good solid support around the hole. Conductor barrels can be bored and equipment retrieved by only losing low-cost drilling consumables. The through hole of the drilling equipment remained in the ground is slightly smaller than inside diameter of the conductor barrel casing.
Method Advantages in the Field
Geonex Horizontal Hammer Boring (HHB) has no penetration problems in any soil classes, even in blasted rock filling. The grade and penetrations is maintained even if boulders, hard bedrock, soft soil or any combination of the above are encountered. HHB technology revolutionizes the principle of pit-launched methods. Instead of pushing from behind, the pipes are pulled from the front by a powerful air percussion hammer.
“Pushing the rope and expecting it to stay on target is impossible without steering. But pull it, and it has no option but to keep on a straight course. It’s as simple as that,” says Geonex Oy senior advisor Jouni Jokela.
Efficient Setup and Lower Costs
Since casing is pulled, no jacking force is required. Therefore, there is no need for thrust or reaction walls or concrete foundations. Pit dug near to entry angle enables drill rig placement, since no anchors are needed. This pit can also work as bentonite receiving pit. Consequently, the hole is completed with a single pass, as the pipe is pulled in along the advancement of boring. Geonex HHB has proven to be superior in total cost efficiency, since initial survey and building costs are minimal, and production rate in boring is high. Geonex HHB works in diameter range of 5 to 48 in.