Introduction
Rock socketed H-piles are small diameter piles. They comprise a steel H section installed inside a grout filled circular hole. The typical pile diameter is 610mm, but 813mm is also adopted.
A characteristic of rock socketed H-piles is that their load bearing capacity is derived exclusively from the lateral friction in rock since the end bearing is neglected. The piles are mainly used in the foundations of non-heavy structures such as footbridges.
General Processes
Rock socketed H-piles are installed by forming a pre-bored hole in the ground with a socket in rock using hydraulic drilling rig. A temporary steel casing will be installed to support the unstable strata and ensure safe working conditions on ground / working platform. “Overburden drilling method” (down-the-hole hammer technique) will be adopted for sinking the pre-bored hole. This technique is suitable for variable ground conditions including boulders and hard rocks.
Subsequent to the pre-boring, the following processes will be followed.
- Air-lifting and pile base cleaning,
- Installation of steel H section,
- Backfilling the bored hole with non-shrink cement grout by tremie method,
- Remove the temporary casing.
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