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1. Bored castin-situ process
Bored cast in situ pile is constructed by digging a hole in the ground by suitable means
such as percussive or rotary method with the use of temporary or permanent casing or
drilling mud. After that, the construction is finalized by filling the hole with reinforced
concrete.Bored cast in situ pile is constructed by digging a hole in the ground by
suitable means such as percussive or rotary method with the use of temporary or
permanent casing or drilling mud. After that, the construction is finalized by filling the
hole with reinforced concrete
First of all, necessary survey need to be completed and pile points need to be marked.
The pile location is set out with respect to the control points by suitable pin marked at
location and checked by Engineer’s representative. The permission to start boring will
be obtained in writing as per the checklist. The guide points (min. 2 nos.) as per
enclosed sketch are fixed at suitable location outside the casing for future reference
and the reference points are guarded. Recording of Ground levels shall be taken prior
to starting of work jointly with GC Engineer. The setting out of each pile shall be agreed
with the Engineer prior to commencement of work.
Prior to starting piling work, pile cap diagonal trenching shall be done at each pile
location to identify the underground utilities. If any utilities are found the same shall be
reported to GC/NMRCL immediately.
Prior to the commence of pile construction operation
 Prepare construction program that involves main project milestones.
 Prepare and maintain all templates and quality check formats
Setting out pile points
 Set out pile points accurately based on the design drawings. According to IS 2911,
the largest allowable tolerance for 60cm pile diameter or more is the greater of
75mm or D/2. For piles with diameter up to 600mm, the tolerance limit is 50mm.

2.  Mark the set out points properly so the points are clear and fix to avoid any
detrimental effect of other activities around the area.
 Use total Station or theodolite to set out pile position. Make sure to recheck these
points before starting the piling activity. Establish temporary reference points (TR)
for this purpose.
Plan preparation for rig movement
 Prepare a layout that illustrate the expected path for rig movement based on the
work program and the planned deployment of resources.
 Check the mast of Hydraulic Rig by spirit level to make sure that the Hydraulic Rig is
vertical.
 Winch vertically shall be checked by plumb bob from the top of the Tripod for
conventional
 Tripod Rig
 The layout shall guarantee easy movement of all rigs without causing disturbances
and problems to other rig operations.
 If the layout is prepared according to the above guidelines, then the team will have
a clear picture on planning the work of next day.
Boring process
1. Position the rig over the established pile point. Check the accuracy of the point by
comparing it with other reference points.
2. Diameter of the cutting tool shall not less than the required pile diameter by more
than 75mm.
3. After rig positioning, drive the casing into the ground. Drive steel casing to a
minimum a depth of 1 m below the ground level to take lateral loads and movements
at site. The steel casing also combat difficulties due to groundwater during piling.
4. Additionally, provide permanent steel casing or liners in the case of loose soils as per
consultant’s advice.
5. stabilize the borehole during boring process using bentonite or other suitable means.

3. 6. Estimate specific gravity of bentonite at regular intervals. Consistency of the drilling
mud shall be controlled throughout the boring as well as concreting operations. This
measure used to stabilize the borehole as well as avoid concrete getting mixed up with
the thicker suspension of the mud.
7. Practiced great care to guarantee straight piles driven.
8. It is recommended to carry out penetration tests to estimate ‘N’ value of the
founding strata. In addition to take and maintain soil or rock samples from the
founding strata, for future reference.
9. It is also advisable to take soil samples from each intermediate soil strata at the
depths specified in the soil test report.
10. Finally, end the boring process upon reaching the designated boring depth. Check
the borehole depth through measuring bailer pipe length after its removal from the
borehole, and use sounding technique to recheck the borehole depth.
Reinforcement placement
 lower reinforcement cage into to the borehole vertically, without disturbing the
sides of the hole.
 Provide sufficient cover blocks all around the cage to ensure sufficient cover.Equip
the reinforcement cage with adequate stiffener bars to avoid sideways sway.
 weld stirrups, stiffeners and laps to prevent breakage.
 According to IS 2911, slump of concrete employed for pile concreting ranges from
150mm to`80mm.
 Prevent interruption of concreting from the start of the process till the end of the
work.
 Concreting begins by lowering tremie pipes in to the borehole. Common tremie
pipe diameter is around 200mm.
 clean borehole bottom adequately before concrete pouring.
 Connect a hopper to the top of tremie pipe. After that, close the joint between
hopper and tremie pipe with a steel plug before concrete first charge.
 Then, fill the hopper with concrete to its full capacity. Once filled, remove the steel
plug to allow the concrete to flow down, and replace the bentonite slurry present in
the pipe.

4.  Keep the bottom end of the tremie pipe embedded, at least 2m, within the laid
concrete. To replace bentonite from bottom upwards and avoid mixing concrete
with water or bentonite.
 The tremie pipe remains hollow after the first charge and each subsequent charge
gets deposited within the already laid concrete.
 extend pile Concreting at least 60cm to 90cm above the cutoff level to ensure good
concrete for proper embedment into pile cap.
 If the cutoff level is at ground level, then permit spill over of concrete till good
concrete is visible.
Applications of bored cast in situ concrete pile
bored cast in situ pile is a strong choice in the following conditions:
 If noise prevention to the buildings located around theconstruction is mandatory or
undesired, then the construction of bored cast in situ pile is the most suitable
option.
 Bored cast in situ pile is ideal as end bearing pile, exclusively when it need to be
socketed into rock.
 When high capacity pile is required, then this type of pile is an ideal choice.
According to IS 2911 part 01- Section 02- 2010, such type of pile preferred for
weights ranges from 150tonnes to 300tonnes.