|Requirement||Bearing Piles & Ground Consolidation to support crane base|
|Techniques||Consolidation Grouting , Micro pile , Sonic|
|Main Contractor||Novelis UK Limited|
After providing technical advice, TechnikGS (TGS) was then awarded the contract for the design and installation of drilled bearing piles and remedial ground treatment works for a new crane base.
The works were carried out inside the existing aluminium re-‐cycling facility in close proximity to operating furnaces and machinery, hence the need for a sensitive geotechnical solution.
The works included the installation of nine bearing piles to depths of up to 7.5 metres below ground level to carry working loads of 125kN in compression and 45kN in tension.
With suspected voiding in the overburden, consolidation grouting was carried out at 24 locations. Due to the proximity of the existing structures, these grouted columns were appropriately reinforced to enhance the stiffness of the predominantly granular soils above rock head.
- Working inside a live industrial facility.
- Sensitive solution required due to proximity of furnace and machinery and possibility of sub-‐surface voids.
- Restrictive access and limited headroom.
- Small rig requirement due to working within a basement area requiring cranage to lower rig into position.
- Extremely tight programme requiring double shifting day and night.
- Tension and compression load requirement.
- Significant penetration required into competent rock.
Hollow bar micropiles were installed with a bit diameter of 100mm and bar diameter of 32mm using high resonance sonic techniques. These piles were installed using a continuous grout flush throughout the installation process. Once the design depth was reached, the drilling rods remained in the pile bore and effectively became the reinforcement.
The bearing piles and consolidation grouting drill holes were installed during five shifts (day and night) to meet extremely tight programme constraints. One of the main advantages of this solution was speed, even when very small scale lightweight equipment was employed.
Our Mini-‐Sonic rig was utilised on the project and was able to overcome obstructions in the overburden and naturally occurring dense sands, before drilling 2 to 3m into the underlying competent sandstone bedrock.