Spiles
AT - Power Set Self-drilling Vacuum Tube Spiles
Drainage works are generally performed to control the inflowing mountain water during tunnel excavation in critical ground conditions. To prevent a potential outflow or ground failure, drainage can be accomplished utilizing additional vacuum admission. As an alternative to conventional vacuum lances, ALWAG internally developed the AT - Power Set Self-drilling Vacuum Tube Spile system.
System components
The AT - Power Set Self-drilling Vacuum Tube Spile is available in standard lengths of 4,0 and 4,5 m and consists of the following system components:
- AT - Power Set Self-drilling Tube Spile Ø 51 x 3,2 mm with perforation holes and threaded connector
- Single-use drill bit Ø 52 mm with HEX 28 connections
- Power Set Drill Steel HEX 28 / T38
- PVC drainage tube Ø 38 mm; L = 3,0 m; standard slot opening width 0,5 mm
- Adapter T38 with integrated impact ring
The spile tube has a perforated toe section of 2,0 or 2,5 m length, the staggered Ø 5-10 mm perforation holes have a standard distance of 50 mm. As a connection to the vacuum pump system, a 2" threaded connector is welded onto the head of the spile.
Installation
AT - Power Set Self-drilling Vacuum Tube Spiles are installed simultan-eously while drilling the spile hole using standard drilling equipment. Thereby, the borehole is drilled using the drill steel which goes through the spile tube and the single-use drill bit.
At the same time, the impact ring of the coupling adapter transfers the impact energy of the hydraulic hammer carefully on the spile tube pushing it into the borehole.
After installation is accomplished, the single-use drill bit remains at the toe of the borehole and the drill steel is pulled back. During the removal of the drill steel, the interior of the tube spile is washed out using the flushing water.
Following installation, the PVC drainage tube which is sealed at its far end is inserted into the toe of the cleaned spile tube. Finally, the hose of the vacuum pump system is connected to the threaded connector of the tube spile.
Operating Mode
When the AT - Power Set Vacuum Tube Spiles are connected to the vacuum pump system, the in-situ mountain water in the loosened side-wall an footwall area is being removed.
By the use of this easy and quickly achievable special drainage method, the critical mountain water inflow can be controlled, especially in critical excavation areas.
Thereby, costly time delays during the excavation process due to problems caused by uncontrolled and sudden water inflows can be avoided and an optimized dewatering can be accomplished.
System components AT - Power Set Vacuum Tube Spile
- Power Set Drill Bit
- Power Set Tube Spile
- Threaded Connector
- Power Set Drill Steel
- Adapter with impact ring
- Adapter with impact ring
Main advantages of AT - Power Set Vacuum Tube Spiles
- One-step installation procedure
- Safe and fast installation using standard drilling equipment
- Careful ground treatment due to self-drilling installation
- Easy adjustment to changing ground conditions
- Unproblematic installation in case of unstable boreholes
- Customized arrangement of perforation holes, drainage filter tubes, and threaded couplings