Pilot pipe jacking is used especially for the underground laying of smaller outer diameters in the DN 200 range. This method enables pipe laying in a resource-friendly way and independent of any preexisting building or structure.
To this end, in a first step, a pilot hole is bored, traditionally by using the soil displacement method. By turning the pilot pipe’s head, which has the shape of a tilted plane, a change in direction can be made and the desired grade and direction be ensured while the pipe is thrusting forward.
Once the pilot bore has been successful, it is gradually widened by different methods until the desired nominal dimension has been reached. Then the final product pipe is advanced forward.
The accurate control of the initial pilot bore is performed via our video measuring systems. These consist, first of all, of a modified theodolite equipped with a video camera and zoom optics. This way, an LED target, mounted in the head of the pilot pipe, can be monitored at all times, using the desired target grade and direction.
Deviations from the target axis can thereby be detected immediately and the correction be initiated through a turning of the pilot pipe. The turning ends as soon as the control axis is located on the center point of the telescope reticle. Afterwards, during the advance, an automatic correction is performed in terms of height and direction. When the center points of the target and the telescope reticle are aligned, the target axis has been reached.
Our video measuring system VM-17 features the additional capability of remote focusing the theodolite telescope via the monitor MF-03.
Further, the camera optic of the system has continuously variable zoom capability.
The theodolites are equipped with a rotatable and precise zenith eyepiece for accurate direction control and adjustment.
The specially designed flat screen monitor MF-03 is configured specifically for use on construction sites. It features a protection class IPxx splashwater-proof housing with the main screen consisting of a special glas-monitor composite that is bonded across the whole surface. Thanks to this technology, the MF-03 is very robust and provides superior image quality, even when viewed from the side.
The LED target suitable for this system is waterproof and features an integrated lithium-ion battery, a two-stage excess temperature warning, as well as an automatic power-saving function. This function monitors the position of the target and is activated when the system stays idle for a longer period of time. A defined turning motion turns the target back on.