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1. Application
GRUNDOBORE 200S is a machine used for the underground installation of pipes. It is especially suitable for installations in confined places, because the stabilisors and the bore-thrust unit are two separate parts which are easily installed even inside tight manholes.
2. General conditions
A launch and a target work pit or a launch and a target manhole are required on the jobsite to operate the GRUNDOBORE 200S.
3. Mode of operation
The GRUNDOBORE 200S is lowered into the launch pit or manhole. An external hydraulic unit provides the hydraulic driving power for the GRUNDOBORE 200S.
The steered boring process proceeds in four different phases::
Phase 1: Core hole bore
The GRUNDOBORE 200S uses a hollow drill bit and a swivelling drill bit guide to bore a core hole into the manhole wall. The hole is bored into the wall of the manhole in the exact position of the intended bore axis.
When working from out of a work pit, phase 1 is dropped.
Phase 2: Inserting the pilot rods
In the second phase the GRUNDOBORE 200S presses the pilot rods right-on-target into the soil while rotating continuously using the displacing method. This is performed with the steering head first, followed by the single pilot rods which are screwed together successively, with the next rod being connected to the last rod sticking out of the soil. The measuring system must be switched on before the steering head can be pushed into the soil. It allows the operator to watch the measuring system constantly while the pilot rods are slowly pressed underground with slow rotating motions. With every deviation from the bore path, rotation is stopped, the pilot rods are pressed forward carefully until the desired direction is taken again. The slanted steering surface of the steering head makes these path corrections possible. Once in the right position again, rotation can start anew. The second drilling phase has been completed on arrival of the pilot rod at the target pit.
Phase 3: Pulling in the retrievable pipe
In the third phase the steering head is disconnected from the pilot rods and replaced by a retrievable pipe with the first conveying screw. This is lowered into the target pit. Under constant rotation, it is pulled back in direction of the launch pit with the first pilot rods. While the retrievable pipe is pulled in along with the pilot rods, it pivots around its own axis. Together with the conveying screw, it transports the soil from the bore hole into the target pit. The single pilot rods appear in the launch pit, ready to be unscrewed and recovered. Simultaneously, the retrievable pipes are screwed together, section for section, at the target pit and then pulled in. The outer diameter of the retrievable pipes is identical with that of the product pipes, therefore the tunnel generated underground is ready to fit them in.
Phase 4: Pulling in the product pipe
Finally the product pipes (e. g. stoneware thrust pipes) are pulled into the soil. A transition piece helps to establish a firm connection between the last retrievable pipe and the first product pipe. Together they are pulled into the soil. In the launch pit, the retrievable pipes are screwed apart one by one and recovered.
4. Advantages
- 1 m manhole version
- Easy mounting by disassembling the system components
- Installation of ND 100 - 150 product and protection pipes
- Transport of the bore spoil into the target pit
- High installation precision
- Pressings up to approx. 25 m
- Location system: laser reflector
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