TUBE UMBRELLA
Tube umbrella, also known as forepoling, are mainly used in underground works, both in mining and civil works for tunnel mouths.
This underpinning element is designed to be used in poor quality soils and rocky masses, thereby delivering terrain consistency immediately.
Rotation and percussion is applied to the RING BIT via the PILOT BIT, leaving the CASING SHOE, which is welded to the starting casing, free. This enables the casing to not rotate, and therefore the torque requirements in the rotating head are much lower.
Ring bit welding in our workshop
Installation of tube umbrella in Santiago de Chile Underground L-3
BRAXIMA forepoling system is made up of high quality steel tubes that range from OD 76.1 mm to OD 139.7 mm with WT ranging from 5.6 to 10 mm. Our RING BITS and PILOT BITS are designed to optimize drilling performance.
The tubes are supplied in custom lengths with normal or double-entry threads to reduce installation time and with 8 mm guide entry to facilitate correct alignment in the assembly process.
Injection Valves
The tubes may be equipped with 12 mm or 16 mm injection valves for opening pressures of 3 bar and 5 bar respectively.
Cement Grout
Cement grout is generally used to fill the space between the tubes and soil.
A lid is used in the end tube and the filler is applied using the grout. Some clients use tubes with one-way injection valves for higher pressure injections and therefore improve filler quality. Consequently, a better soil reinforcement is achieved.
Technical table
Steel Grades
| Steel degree | Yield point | Tensile strength | Elongation |
|---|---|---|---|
| min. N/mm2 | N/mm2 | min. % | |
| S355 | 355 | 490-630 | 22 |
| MP-80 | 552-752 | 689 | 18 |
Technical table
Dimensions
| Braxima Code | Max. Wall Thickness |
|---|---|
| mm | |
| BXA76.1 | 8 |
| BXA88.9 | 8 |
| BXA101.6 | 8 |
| BXA114.3 | 10 |
| BXA139.7 | 10 |
BXA76.1 – BXA88.9 – BXA101.6 – BXA114.3 – BXA139.7
| Braxima Code | Casing O.D. | W.T Max. | Ring Bit I.D. | Ring Bit O.D. | Pilot Bit | Thread | Grade |
|---|---|---|---|---|---|---|---|
| BXA76,1 | 76,1 | 8 | 40 | 90 | 58 | R32 | S355/N80 |
| BXA88,9 | 88,9 | 8 | 52 | 94,5 | 70,9 | T38 | S355/N80 |
| BXA101,6 | 101,6 | 8 | 62 | 106,6 | 83 | T38 | S355/N80 |
| BXA114,3 | 114,3 | 10 | 70 | 120 | 92 | T38 | S355/N80 |
| BXA139,7 | 139,7 | 10 | 94 | 148 | 116,7 | T45 | S355/N80 |
Starter tube, Extension tube, End tube
Starter tube, Extension tube, End tube
Ring bit, Starter tube, Pilot Bit