© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in Sands

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© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in Sands

( )( ) Q zf zp z

sQ p Lf

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© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in Sands

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© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in Sands

'

0 '' tan

'

vo

z L

z to Lf K

z L to Lf f

Pile type K

Bored or Jetted K0=1-sin’

Low displacement driven K0=1-sin’ to K0=1.4(1-sin’)

High displacement driven K0=1-sin’ to K0=1.8(1-sin’)

DasL’ 15D

구조물 설계기준L’ 20D

= 0.5’ - 0.8’Additional equations: 11.40 – 11.43

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© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in Sands구조물 설계기준(Aas, 1966)

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© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in SandsCorrelation with SPT

1 60

2 21 60

1 60

0.291

(1976)

0.02 ( )

0.2 ( / ) 10 /

0.01 ( )

(1985)0.224 ( ) ( )

av a

av a

a

MeyerhofHigh displacement

f p N kPa

N tf m tf m

Low displacement

f p N kPa

Briaudf p N kPa

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구조물 기초설계기준식 5.2.14

© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in SandsCorrelation with CPT

' cf f

Electric cone

Mechanical cone

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© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in Clays 1. method

uf s

s uQ fp L s p L 8

- 육상말뚝에는 Woodward 곡선 사용

- 긴 강관말뚝에서는 API(1982) 곡선 사용

© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in Clays 2. methodVijayvergiya and Focht (1972)

' 2av vo uf s

1 1 1'oA A A

L

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© Park 기초공학 lecture_05_pile_foundation

Qs –in Sands and Clays: method

tan '' /

1 sin ' ( )

1 sin ' ( )

R

R

R

R

Kdrained friction angle of remolded clay sand

K earth pessure coefficient

K NC

K OCR OC

0'vf

토질

점토 0.20 – 0.25실트 0.25 – 0.35모래 0.35 – 0.50

값의범위

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© Park 기초공학 lecture_05_pile_foundation

Qs – Shaft capacity in Clays: CPT

' cf f

Correlation with CPT

21500tf/mp cq q

2f f 10tf/ms c

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© Park 기초공학 lecture_05_pile_foundation

Determination of Ap and As

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© Park 기초공학 lecture_05_pile_foundation

Determination of Ap and As – Circular Piles

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© Park 기초공학 lecture_05_pile_foundation

Determination of Ap and As – H Piles

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If L > 5B

© Park 기초공학 lecture_05_pile_foundation

Allowable capacity of pile

uall

QQFS

,p L sall

p s

Q QQFS FS

FS = 2.5 ~ 4 적용

도로교표준시방서(1996)평상시: 3.0지진시: 2.0

재하시험의경우평상시: 2.5지진시: 1.7

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© Park 기초공학 lecture_05_pile_foundation

Point bearing capacity of piles on rock

2

1

tan 45 '/ 2p uq q N

N

( )( ) 5

u labu design

qq

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443

© Park 기초공학 lecture_05_pile_foundation

Axial Capacity of Single Piles - SummaryQu in Clay

QpQp = 9su (Meyerhof)

Qs3 methods (, , method)CPT

Qu in Sand

QpMeyerhofNAVFACCPT

Qs Use and (also depends on method of installation)SPT or CPT

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