Large prefabricated pile foundation,a solution for high-rise buildings in

Ha Noi and HoChiMinh city

Bao Viet NGUYENNational University of Civil Engineering, Hanoi, Vietnamnbviet@sdh.nuce.edu.vn

A LOT OF BUILDINGS ARE RISING IN HANOI & HOCHIMINH CITY

BORED PILE FOUNDATION

Bored piles- Very high bearing

capacity- A lot of mud &

construction trash with a swampy site

- Cost Increased because of environmental treatments

- Construction time might be extended

Prefabricated piles with large size- High bearing

capacity up to 8000kN

- No construction trash with clean site

- Properly reduce cost and construction time

APPLICABILITY OF PREFABRICATED

PILES FOUNDATION

Where: Rfea = feasibility ratioQaua = Allowable bearing capacity

of pile foundation on area unit p = total pressure acting on foundation

Rfea = Qaua / p / FSfea

1.0 : high applicability

< 1.0 : low applicapility

APPLICABILITY OF PREFABRICATED

PILES FOUNDATION

Where: Pa = Allowable bearing capacity of a pile

d = pile size

Qaua = Pa / (3dx3d)

p = 15kPa x number of storeys

Distribution

maps of

soil types

in area of

old Ha Noi

Sub-soil type Name Description Distribution

ASingle layer

A1 Clayed soils, up to 30m thick, PI=0.15~0.4, SPT=12~15, E0=10Mpa

West Từ Liêm;Đông Anh

A2 Clayed soils, up to 30m thick, PI=0.35~0.6, SPT=8~12, E0=5~8Mpa Hà Nội center

BTwo

layers

B1

Upper layer: Clayed soils, up to 10m thick, PI=0.15~0.4, SPT=12~15, E0>10Mpa;Lower layer: Medium sand, medium dense, up to 20m thick, SPT30,E0>20Mpa.

North Đông Anh

B2

Upper layer: Clayed soils, 5~10m thick, PI=0.35~0.6, SPT=9Lower layer: small sand, medium dense, up to 20m thick, SPT12, E0>10Mpa;

South Đông Anh and

Thanh Trì; Gia Lâm

CMulti layers with

weak soil

C1

Upper layer: Clayed soils, up to 10m thick, PI=0.15~0.4, SPT=12~15, E0=10Mpa;Middle layer: Organic soils, up to 10m thick, PI>0.8, SPT=5, E0=3~5Mpa;Lower layer: Medium sand, up to 10m thick, SPT30, E020Mpa;

North Đông Anh

C2-3

Upper layer: Clayed soils, up to 10m thick, PI=0.35~0.6, SPT=5~8, E0=6~8Mpa;Middle layer: Organic soils, up to 15m thick, PI>1.2, SPT=2~4, E0=3Mpa;Lower layer: Sandy soil, up to 10m thick, SPT20, E015Mpa;

Đông Anh, Gia Lâm (small

area) Thanh Trì,

South Từ Liêm

Main soil strata types in the area of Ha Noi

Feasibility ratio of prefabricated square piles for 15 storeys buildings – Hanoi Area

Pile size (cm)

Feasibility ratio of prefabricated square piles for 20 storeys buildings – Hanoi Area

Pile size (cm)

Feasibility ratio of prefabricated square piles for 25 storeys buildings – Hanoi Area

Pile size (cm)

Feasibility ratio of prefabricated square piles for 30 storeys buildings – Hanoi Area

Pile size (cm)

Distribution

maps of

soil types

in area of

HoChiMinh

city

Sub-soil Description Distribution

A1

Upper layer: Clayed soils (CuChi, ThuDuc), up to 10m thick, PI=-0.25~0.25, E013Mpa;Middle layer: Clayed soild (Trang Bom), >10m thick, PI=-0.23~0.4; E08Mpa.Lower layer: Medium sand, medium dense, large thickness, E0>20Mpa.

Northern of ThuDuc & CuChi

and a part at central of the city

A2Upper layer: Clayed soils (BInhChanh), up to 10m thick, PI=-0.25~0.25, E013Mpa;Middle and Lower layer are the same as A1

North-western of CuChi and most of

the central

B1

Upper layer: Organic layer (CuChi, ThuDuc), up to 10m thick, PI=1.0~2.5, E01Mpa;Middle layer: Clayed soild (Trang Bom), >10m thick, PI=-0.23~0.4; E08Mpa.Lower layer: Medium sand, medium dense, large thickness, E0>20Mpa.

NhaBe, BinhChanh district,

southern of ThuDuc, South-

Western of CuChi, along SaiGon river and coastal area.B2

Upper layer: Organic layer (CuChi, ThuDuc), up to 20m thick, PI=1.0~2.5, E01Mpa;Middle and Lower layer are the same as B1

B3Upper layer: Organic layer (CuChi, ThuDuc), up to 30m thick, PI=1.0~2.5, E01Mpa;Middle and Lower layer are the same as B1

Main soil strata types in HoChiMinh city

Feasibility ratio of prefabricated circle piles for 15 storeys buildings – HoChiMinh city

Pile size (cm)

Feasibility ratio of prefabricated circle piles for 20 storeys buildings – HoChiMinh city

Pile size (cm)

Feasibility ratio of prefabricated circle piles for 25 storeys buildings – HoChiMinh city

Pile size (cm)

Feasibility ratio of prefabricated circle piles for 30 storeys buildings – HoChiMinh city

Pile size (cm)

Case history of 20 storeys twin buildings

45x45cm of piles with bearing capacity of 1800kN

Settlement of about 2cm with 70% design load

CONCLUSIONS - HANOI

- Large prefabricated pile foundation could be applied to the high-rise buildings up to 30 storeys.

- In Ha Noi, soil types of A1 and B1 are most suitable for prefabricated pile foundation of buildings up to 30 storeys.

- In case of B2, C1 soil types, the applicability of the piles for buildings up to 25 storeys is highly reliable.

- Buildings of 15 storeys and buildings of 20 storeys could be settled on C2-3 and A2 soil types, respectively, with large size of pile (45x45cm and 50x50cm).

CONCLUSIONS – HOCHIMINH CITY

- In HoChiMinh city, soil types of A1 and A2 are most suitable for prefabricated pile foundation of buildings up to 30 storeys but a careful consideration must be carried out for 30 storeys buildings.

- In case of B1 soil types, the piles foundation could be applied for buildings up to 20 storeys with high reliability.

- Buildings of 15 storeys could be settled on B2 and B3 soil types.

CONCLUSIONS

- To apply the large prefabricated pile, the construction site must be large enough so that a big driven/jacked rig could have a space to work.

- Using large prefabricated pile could save money because of almost no environmental treatment and using prestressed concrete.

- Last but not least, the construction site was pretty clean therefore the construction works of foundation could be carried out smoothly and the construction time may be reduced.

THANK YOU FOR

YOUR ATTENTION