The Construction Process of Bored Piles

BORED PILES CONSTRUCTION

Bored piles construction is done using the suitable rotary drills depending on the diameter, depth, condition of the soil and construction method. Usually bore-holes are stabilized with a temporary or permanent casing. The common material used for the casing is steel and it is also normal called as steel casing. The length of the steel casing is also determined from the soil conditions that are discovered at the actual site.

SETTING OUT

The location of the bored piles must be set out and marked by the subcontractor’s surveyor according to the approved setting out drawings given by the Consultant. The surveying details for each location should include the reduced levels and coordinates. The place that is surveyed and marked as the pile position shall not be disturbed prior to the commencement of boring works.

DRILLING

All the associated technical information such as presence of services, pile coordinates, platform and cut-off levels, validity of drawings etc need to be verified by the client's representative to begin the operations. If needed, after setting up the pile location by the surveyor, a temporary casing will be placed according to the ground conditions. The vertical accuracy of the casing will be checked while the installation process is done. Rotary Kelly bar and the auger or bucket method are used to carry out excavation of the soil inside the casing or bored holes. Once the drilling process begins, the auger or drilling bucket is then used to drill into the ground until the required depth or till it hits a hard rock which is capable of load bearing.

The point of when encountering a hard rock while boring as it is defined in the contract specification, for example, once the auger or drilling...

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...be concreted using the “tremie’ method. The type of concrete used will be a self-compacting mixed concrete and it will be discharged by a tremie pipe, which is then lowered uniformly aligned to the middle while descending until the bottom of the bored hole followed by filling of concrete. The level of concrete in the borehole was recorded after each truck discharged and the plotting of the graph will be against theoretical. The concrete should be continuously embedded in one length to make sure that the discharge of concrete is level of the impurities, which may be seen at the top part of the rising head of the concrete. The testing of all the piling work should be done by following the Engineer’s or Engineers Representative’s instructions. Completed piles shall be temporarily fortified and to be backfilled to ground level with a suitable material the following day.