346260332-Under-Reamed-Piles-1-10-09.pptx

Pile Load Test

1. UNDER REAMED PILES By J.C.WASON

2. COMPLETED PILE SINGLE UNDER REAMED PILE D DU D DU 1.5 DU 350 TO 400 2D APPROX 350 TO 400 FOR BRACKET 2D 2000 Mtn 350 TO 400 FOR BRACKET 150 MIN 80 200 WIDTH OF WALL A B DOUBLE UNDER REAMED PILE A B

3. UNDER REAMED PILES : Manually Bored Cast in Situ S hallow D epth Piles, 3m to 8m in length, 200mm to 500mm dia , with Single or Double Under Reams. MERITS : Easy to install, manual boring with simple equipment, can be worked with semi skilled labour , Hence economical. DEMERIS : Limited depth (3 to 8m) Limited load carrying capacity (15 to 30 Tonne capacity), Hence can be adopted for small low rise bldgs.

4. Applications of UR piles : For foundations of bldgs in Black Cotton Soils. For foundations of bldgs in filled up soils. As an alternate to ordinary Piles. As Anchor (Tension) Piles.

5. UNDER REAMED PILES – APPLICATIONS : IN BLACK COTTON SOILS : Primarily developed by CBRI, Roorkee as appropriate type of foundations for low rise buildings in Black Cotton Soils. These help to transfer loads to strata not affected by seasonal volumeteric changes in such soils, ( normally 2 to 3 m below ground level). IN FILLED UP SOILS : Also adopted for building foundations in filled up soils where good firm soils may lie at shallow depths of 3 to 6 m below ground level, but top soil, being filled up, is not suitable for placing foundations.

6. UNDER REAMED PILES – APPLICATIONS (CONTD.) : 3. AS AN ALTERNATIVE TO NORMAL PILES : Recently, C.P. Kukreja & Associates have adopted U.R. Piles Foundations as an alternative to Normal Pile Foundations for some of their projects in Gurgaon (Example : 13 storeyed Resedential b uildings for their Heritage City Project in Gurgaon). AS TENSION PILES : under deep underground water tanks, under deep basements with high water table, and under Tall H.T. Electric Towers.

7. PROCEEDURE TO INSTALL UR PILES : Make a bore hole with a manual auger. Enlarge bore holes at locations of under ream bulb(s) with the help of collapsible blades. Place reinf cage in the bore hole. Place concreting by Tremie Pipes.

8. S AFE LOAD FOR VERTICAL BORED CAST-INSITU UNDER REAMED PILE IN SANDY AND CLAYEY SOILS INCLUDING BLACK COTTON SOIL S Size Ø of pile (mm) L (m) Capacity (KN) Increase in cap per 30 cm length Decrease in capacity/30cm length SUR DUR SUR DUR SUR DUR SUR DUR 200 3.5 3.5 80 120 9 9 7 7 Up lift resistance ~ 50% of comprn. load capacity 250 3.5 3.5 120 180 11.5 11.5 9 9 300 3.5 3.5 160 240 14 14 11 11 375 3.5 3.75 240 360 18 18 14 14 400 3.5 4.0 280 420 19 19 15 15 450 3.5 4.5 350 525 21.5 21.5 17 17 500 3.5 5.0 420 630 24 24 19 19 SUR = SINGLE UNDER – REAMED PILE SUR = DOUBLE UNDER – REAMED PILE

9. COMPLETED PILE SINGLE UNDER REAMED PILE D DU D DU 1.5 DU 350 TO 400 2D APPROX 350 TO 400 FOR BRACKET 2D 2000 Mtn 350 TO 400 FOR BRACKET 150 MIN 80 200 WIDTH OF WALL A B DOUBLE UNDER REAMED PILE A B

10. BORING THE PILE SHAFT IN GRANULAR SOIL USING TEMPORARY CASING AND SHELL STAGE – 1

11. REINFORCEMENT AND TREMIE TUBE INSERTED IN PILE SHAFT AT THE START OF THE CONCRETING OPERATION STAGE – 2 PLUG TREMIE TUBE REINFORCEMENT TEMPORARY CASING SLURRY

12. CONCRETING COMMENCED WITH WATER AND SILTY SLURR BEING DISPLACED STAGE – 3

13. WATER AND SLURRY DISCHARGING AS CONCRETING PROCEEDS STAGE – 4 NOTE :- CONCRETING DEEP PILES MAY BE FACILITATED BY EXTRACTING THE TEMPORARY CASING IN STAGES AND REMOVING THE TREMIE TUBE IN CONCRETE

14. WITHDRAWING TEMPORAY CASING STAGE – 5 NOTE :- CONCRETING DEEP PILES MAY BE FACILITATED BY EXTRACTING THE TEMPORARY CASING IN STAGES AND REMOVING THE TREMIE TUBE IN CONCRETE

15. COMPLETED PILE STAGE – 6 NOTE :- CONCRETING DEEP PILES MAY BE FACILITATED BY EXTRACTING THE TEMPORARY CASING IN STAGES AND REMOVING THE TREMIE TUBE IN CONCRETE

16. CASE STUDY OF A BLDG WITH UNDER REAMED PILE FOUNDATIONS

17. Case Study : Staff Quarters for FSL , Rohini , New Delhi – Under Reamed Pile Foundations DATA : No of Storeyes : 4 Structural System : Load Bearing Brick Masonry Bldgs without Basement (Wall Thickness : 230mm, Bricks Masonry in GF : 230 – 10 – H2 (Bricks class : 10, Cement mortar : 1 : 4, Wall Tk : 230mm) Sesimic Zone : 4 (Delhi), Imporance Factor : 1 (Residences) (Bldg Strengthened for EQ Resistance as per IS: 4326 – 1976) Storey Ht : 3m Soil Strata at Site : Loose Filled up soil for top 2.5 to 3.5 m, Firm soil below Foundations :Under Reamed Pile Foundations with RCC Pile caps, Size, Type, length and Capacity of Piles : 400 mm dia Bored Cast in Situ Single Under Reamed Piles, 8m long Capacity : 31 Tonnes (310KN) Conc Mix for Piles and Pile Caps : M 25, Steel Reinf Grade : F e 415

18. Showing location of under reamed piles, pile caps and grade beams

19. DETAILS OF A TYPICAL PILE CAP WITH SINGLE (ONE) PILE PILE CAP SIZE : 600mm x 600mm X 500 mm Thick Conc Mix for Piles and Piles Caps : M 25 Steel Reinf . Grade : Fe 415 Type of Piles : 400 mm dia Single Under Reamed Bored Cast in Situ Piles, Friction cum Bearing Piles Length of Piles : 8m Capacity of Piles : 31 Tonnes (310 KN)