BERNOLD TYPE SHEET

TUNNEL STEEL COMPONENTS PRODUCTS & INSTALL

The Bernold Type Sheet is a tunnel support which is a method that allows placing of vibrated concrete lining immediately after excavation is completed. The result is a vault composed by Bernold Type Sheet and vibrated concrete which provides a uniform and predetermined resistance remaining firmly tighten to the ground.

HINGED STEEL ARCHES

These sheet supports are made of wide flange beam, bent to the required concreting radius and provided with hinges to make dismantling and transport to the face easier.

They are sized to stand thrusts of concrete backfilling the sheets and also any pressure derived from rocks before concrete hardening takes place and therefore accomplishment of full resistance capability of concrete lining is not achieved yet.

SPECIFICATIONS

The Bernold Type Sheet, grooved, undulated and bent to a certain radius, manufacture in sizes up to 3mm* thickness, dimensions of 1098x1800 mm* and 9 undulations** on each line. They make the concrete forming and act as concrete framework when totally forged. Sheets are assembled over steel arches, overlapped to each other and hooked up with pins. After assembling is completed an actual surface of 1.50 square meters is covered by each sheet. Sheets are provided with undulations on every 122 mm, which can be considered equivalent to a concrete framework structure.

*Any other width/length sizes and **undulation can be manufactured upon your request. Hence, please contact us at technic@momentum-metal.com for your requested dimensions.

STEEL ARCH STRECTHERS

Manufactured in tube are limited at their edges for lengthways bracing to arches. To adjust stretchers, special plates are incorporated to the arches.

ASSEMBLING PROCESS

Once excavations is completed and the area duly cleaned up, 1 to 3 arches will be erected pending on excavation carried out. Distance between arches is determined by stretchers, usually 120 mm; equivalent to a 9 undulation sheet; equivalent to 1098 mm less 122 mm derived from overlapping of last and first undulation. Hence last undulation must always be clear when carrying our front coverage.

Starting from the bottom, sheets are placed and anchored to arches at both sides of tunnel, while concrete backfilling between sheets and rocks are simultaneously carried out. Subsequent to concrete pouring, vibration should be done till concrete juts out from sheet grooves. Standard concrete 250/300 kg, with a water/cement factor of 0.4-0.5 hard plastic consistency, grain 30 mm fixed by the pump is normally used.

Netting material used in front coverage cannot be recuperated. Once Bernold Type Sheet lining is completed, it is usually finished with a cover of shot concrete, applied to the sheet that acts as an excellent support.

ASSEMBLING & ADVANTAGES

The Bernold Type Sheet application is a system that is usually substituted for waste water / rainwater tunnels, HES or dam tunnels, shafts descents and concrete belts and pre-shafts in mining galleries and usually in transport tunnels such as road, subway, railway, pedestrian etc.

Tunnel excavation starts in the beginning of this system which is applied to the system without the need for any concrete mold and without waiting for the opening of the tube to start at the same time as the concrete casting is designed to be taken as soon as possible to operate.

In tunnel entrances, gallery assemblies, on weak floors, the mold installation immediately reaches the required strength without any risk and by moving along with the tunnel mirror. It’s especially preferred for variable cross sections and to save mold cost.

We present Bernold Type Sheets and Rock Bolts to all contractors worldwide.