The development of open shield technology is based on mining techniques under the cover of manually controlled hood shields.
Braumann supplies controllable open shield tunneling machines starting at a nominal diameter of DN 1200 and reaching up to DN 3000. They are equipped with an excavator arm (draw hooks) for gravel soil and milling heads for solid rock.
Open shield technology has been successfully applied by Braumann since 1985. All tunneling machines are developed, built and serviced at the company´s own technical service centre in Antiesenhofen, Austria.
• Advantages of open shield technology
Due to the open and visible working face the soil can be mined and documented easily
Unexpected obstacles are recognized immediately and can be removed without special recovery
High efficiency mining especially in dry and soft soil
Application in solid rock with drilling heads is possible
Walkability ensures fast and easy repair- and service-activities
Long segments can be constructed and connected under ground
Pinpoint accuracy due to state of the art surveying- and control-technology
• The procedure of open shield technology
When it comes to mining soft soil, draw hooks gained the most acceptance.
The excatator arm can be adapted with ripper teeth or a hydraulic hammer can be installed.
To put it brief and simple, open shield technology proceeds in three typical steps:
Loosening - Loading - Hoisting
Excavator arm at the working face
The soil is loosened at the working face by a telescope excavator arm or a cutting head, protected under a hood shield, and then pulled onto the installed conveyor-belt.
Loading excavated soil via conveyor-belt
The conveyor-belt transports the excavated soil to the stand-by-conveyor-bucket
Conveyor-bucket is hoisted above ground
The full conveyor-bucket is pulled into the starting pit by hydraulic winches and steel ropes, hoisted to the surface and taken to the deposit.
• Special solutions
As jacking specialist Braumann has developed various technical options:
Hoisting the inside of a jacking machine
Production of open shield jacking machines and their connection to given facilities under ground
Production of open shield jacking machines without target pit, thus with a machine pipe that stays under ground while all other technical devices are dismantled
Jacking through known obstacles
Jacking in contaminated grounds (via full face technology)
Jacking in grounds containing suspected war relicts with the assistance of a pyrotechnical specialist watching the working face