SPECIFICATION FOR PILLS
PILES
BORED CAST-IN-SITU CONCRETE PILE General
This specification covers the piling work required for the construction of intermodal terminal at Varanasi. Geotechnical investigations for the area where on land facilities and jetty structure are coming have been completed. Report may be referred to for sub soil parameters. The area falls in "Indo Gangotri plains' and soil at the project side belongs to Indo gangotri alluvial and are river deposit of the river Ganga its tributaries. However general site stratigraphy is as follows
In the river bank
- Hard clayey silt
In the river
- Hard clayey silt under lain with very
dense silty sand
Tenderer may carry out additional investigation if felt necessary by him. Claims and objections of site and subsoil conditions shall not be entertained.
1.02.01
Codes
IS:2911 (Pari 1/Section 2)-1979 : 'Code of practice for design
&
construction of Bored Cast-in-Situ concrete piles'shall be referred to in conjunction with this specification during the entire design & construction work. If for any material or workmanship, appropriate Indian Standards or Codes are not available or have not been adequately specified in the Technical Specification, such materials & workmanship shall conform to other suitable Standard & Codes.
1.02.02
Design
The piles shall be bored cast-in-situ cylindrical type RCC piles and shall be founded on suitable approved strata to achieve the design capacity.
1.02.03
Materials
All the materials proposed to be used, shall be free from any objectionable substances, shall conform the following stipulation. Any testing required to prove the suitability of such materials should be carried out.
1.02.03.01 Reinforced Cement Concrete for Piles and pile caps shall be with minimum Cement content of 425 Kg/'m
3
for piles .The slump of concrete for piles shall be between 160 mm to 180 mm. The water-cement ratio shall not
exceed 0.45. To achieve the specified slump using specified water cement ratio without compromising with strength, if required, suitable admixture shall be used subject to approval of the Purchaser.
1.02.03.02 Preliminary mix design shall be done in accordance with IS: 10262-1982 & SP:23 subject to approval of the Purchaser. Cube tests, slump test & other relevant tests for preliminary mix design and Routine cube test, slump test for regular concreting shall be carried out at site / site laboratory at contractor's own cost. Concrete cube tests shall be done as per IS:516-1959. Frequency of cube test shall be guided by clause 15.2 of IS: '456-2000. Slump tests (apparatus conforming to IS:IS:7320-1974) shall be carried out at least once for each pile or more frequently, if desired by the Purchaser.
1.02.04
Equipment
& Accessories
The equipment & accessories should be compatible with the type of sub-soil, method of installation, type of founding strata
&
required penetration in the founding strata.
The capacity of rig shall be adequate so as to bore upto required depth with specified diameter. Rig shall be equipped with suitable chisel to penetrate through any local obstruction/ hard strata.
1.02.05
Construction
1.02.05.01
The permissible positional deviation in horizontal direction shall not be exceed 1.5 % from the
designed location in more in case of piles having diameter more than 600mm.
1.02.05.02 Stabilisation of the side of borehole shall be done by the use of bentonite
slurry, Direct Mud Circulation (DMC) process shall be adopted . In such cases the bentonite slurry must be used at least from the level of sub-soil
water, as the hole shall then be always kept almost full with the fluid. The
specific gravity of bentonite slurry shall be in the range of 1.05 to 1.10. This shall be checked regularly for each or at any change in its specified consistency. Pressure of slurry pump shall be sufficient enough to clear out all cuttings efficiently from the hole. Prevention of side collapse of boreholes shall be taken care by with use of temporary casing if necessary.
At the last stage
of
boring or in intermediate hard layers chisel may be used. The piles shall be installed with due consideration for safety of adjacent structures by a method, which leaves their strength unimpaired, and which develops and retains the required bearing resistance. 1.02.05.03 Reinforcement as required shall be made into stiff cages sufficiently welded
to withstand handling without any damage or distortion. Reinforcement shall be placed immediately after cleaning and inspection of the bottom of bore holes. The reinforcement should be supported away from the sides of the shaft by means of suitable space block to ensure concentric alignment in the shaft. Steps shall be taken to ensure correct positioning during concreting of reinforcement in the piles without any distortion.
