A Pile is basically a long cylinder of a strong material such as concrete that is pushed into the ground to act as a steady support for structures built on top of it. Piling is used in the construction of buildings, bridges and other projects when the soil isn’t able to support the weight necessary for the structure at shallow depth. Pile foundations are one of the deep foundations, it can be constructed as Friction pile, and End bearing pile. End bearing piles transmit most of their load to the load bearing layer (rock) and most of the pile capacity inferred from the end bearing point. Friction piles transmit their load in to the soil layers which the pile pass, via surface friction with the surrounding soils. The different type of pile such as : friction pile or End bearing pile can be identified through the site geological borehole report. Before starting the project, it is very important to ensure the following steps
• Before starting works, ensure the all Authority approvals are in place.
• Pre-crack survey report. This will be conducted by Client and keep a copy in the site, including the copy of notification letter sent to neighbors.
• Residual Noise and Vibration readings. Need to conduct before the mobilization of machinery or stop all the machinery and conduct as per the SLS of The National Environment Act, No. 47 of 1980 under section 32 for Noise and Central Environment Authority regulation for Vibration.
• Soil investigation report and contours prepared. These contours shall be based on the borehole log details available in soil investigation report and needs to be updated once the pile borehole records are received.
Setting out of a pile
The coordinates of each of pile point obtain from approved drawings and mark the position by using Total station. Then provide 2 off set points at a suitable radius as shown below. These off set points are used to check whether the casing installed at a particular point properly, and it is necessary to check the verticality of casing using spirit level. In generally, 6 m, 8 m, 10 m and 12 m casing lengths are commercially available. The installation of casing length can be varied for each project based on site condition and the groundwater level at the site. The soil boring process starts with Soil Augur and continue it to an approximate depth of 6 m. then the temporary casing will be installed into the borehole.
Pile concreting
Pile concreting is done using pipes. Since the pile depth is high, concrete will be segregated when pouring. So that pipes are used. A hopper is installed with the pipe. So that the concrete into the hopper and the concrete will travel through the pipe to the toe level. To remove the air voids the pipes take to up and down during the concreting Compaction cannot be done. The volume of the hopper is 1m3 pipes are in the length of 3 meters, 2 meters and 1.5 meters. Pipe removal also happen simultaneously during concreting. The minimum pipe embedment into the concrete should be 1.5 meters.
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