ONSHORE WINDMILL FOUNDATIONS

(1)

Doctoral Thesis Structural

Mechanics

Report TVSM-1029WAEL MOHAMED ONSHORE WINDMILL FOUNDATIONS - Evaluation of new proposals

WAEL MOHAMED

Evaluation of new proposals

1029HO.indd 1

1029HO.indd 1 2017-12-17 17:12:082017-12-17 17:12:08

(2)

(3)

DEPARTMENT OF CONSTRUCTION SCIENCES

DIVISION OF STRUCTURAL MECHANICS

Printed by V-husets tryckeri LTH, Lund, Sweden, December 2017 (Pl).

For information, address:

Division of Structural Mechanics, Faculty of Engineering LTH, Lund University, Box 118, SE-221 00 Lund, Sweden.

Homepage: www.byggmek.lth.se

ISRN LUTVDG/TVSM--17/1029--SE (1-192) | ISSN 0281-6679 ISBN 978-91-7753-525-6 (print) | ISBN 978-91-7753-526-3 (pdf) DOCTORAL THESIS

WAEL MOHAMED

ONSHORE WINDMILL FOUNDATIONS

Evaluation of new proposals

(4)

(5)

i

(6)

(7)

iii

(8)

iv

(9)

v

(10)

vi

(11)

1

(12)

(13)

3

(14)

4

b) c)

a)

(15)

5

D

dfco ^θ Edge beam

t

(16)

6

(17)

7

(18)

8

(19)

9 H

h

M

(20)

10

𝑀 =¹₂𝜌_𝑎𝑣_ℎ²𝜋𝑅_𝑟²ℎ𝐶_𝑀𝐷𝐺_𝐷

ρ h

𝐶_𝑀𝐷 = 𝜀_𝑇𝐶_𝐷𝑇(_3+3𝛼¹ +¹₆) + 𝜀_𝑁𝐶_𝐷𝑁+ 𝐶_𝑇

ε

ε α

α

𝐺_𝐷 = 1 + 2𝐼_𝑟𝑒𝑓(0.75 +^5.6_𝑣

ℎ)𝑔_𝐷√𝐾√1 + 𝑅_𝐷 𝑔_𝐷

(21)

11 𝑔_𝐷

𝑔_𝐷

˃ 𝑔_𝐷 −0.3 sin (𝜋 𝑣_ℎ− 𝑣_𝑟

𝑣_𝑜𝑢𝑡 − 𝑣_𝑟) + 3 sin (7𝜋

8 ( 𝑣_ℎ− 𝑣_𝑟

𝑣_𝑜𝑢𝑡− 𝑣_𝑟)) + 3 0.15sin (𝜋 𝑣_ℎ− 𝑣_𝑟

𝑣_𝑖𝑛− 𝑣_𝑟) + 0.15 0.45 𝑣_ℎ− 𝑣_𝑟

𝑣_𝑜𝑢𝑡 − 𝑣_𝑟+ 0.15 2.6 𝑣_ℎ− 𝑣_𝑟

𝑣_𝑜𝑢𝑡 − 𝑣_𝑟+ 0.2

𝑀 = ∫₀^ℎ¹₂𝜌_𝑎𝑣²𝐶_𝑓𝐾_𝑑𝐾_𝑧𝐺_𝐷𝐷(𝑧)𝑧𝑑𝑧

(22)

12 0

5 10 15 20 25 30 35 40

5 7 9 11 13 15 17 19 21 23 25

Maximum moment on the foundation (MNm)

Wind Speed at hub height (m/s)

0 5 10 15 20 25 30 35 40

27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59

Maximum moment on the foundation (MNm)

Wind Speed at hub height (m/s)

(23)

13

(24)

(25)

15

(26)

16

𝑀_𝑡= 𝑀 + 𝐻(𝑑_𝑓) 𝑉 = 𝑁 + 𝑊_𝑓+ 𝑊_𝑠 − 𝐹

N H

R y

h

Wf

σ N

y

H M

R be

VH e

Foundation base level Natural ground level

a) b)

c)

d)

df

Wind pressure

a)

N H

R y

h

Wf

σ N

y

H M

R be

VH e

a) b)

c)

d)

df

Wind pressure

a)

N H

R y

h

Wf

σ N

y

H M

R be

VH e

a) b)

c)

d)

df

Wind pressure

a)

b)

c) Aeff

e

leff le

beff

be

(27)

17 𝜎 =_𝑏 ^𝑉

𝑒𝑓𝑓𝑙_𝑒𝑓𝑓+ _𝑏 ^6𝑀^𝑡

𝑒𝑓𝑓𝑙_𝑒𝑓𝑓²

( ) 𝐴_𝑒𝑓𝑓 = 2 [𝑅²cos⁻¹(_𝑅^𝑒) − 𝑒√𝑅²− 𝑒²]

𝑙_𝑒𝑓𝑓 = √𝐴_𝑒𝑓𝑓^{𝑅√1−(1−}

(𝑅−𝑒) 𝑅 )² (𝑅−𝑒)

𝑏_𝑒𝑓𝑓 = ^𝑙^𝑒𝑓𝑓

𝑅√1−(1−^{(𝑅−𝑒)}_𝑅 )²

(𝑅 − 𝑒)

𝑞_𝑎𝑙𝑙 =^𝑐𝑁^𝑐^𝜉^𝑐^+𝑞𝑁^𝑞^𝜉^𝑞^+0.5𝛾_𝑓 ^′^𝑏^𝑒𝑓𝑓^𝑁^𝛾^𝜉^𝛾

𝑠

γ

𝜉_𝑐, 𝜉_𝑞, 𝜉_𝛾

(28)

18

γ

𝑞_𝑎𝑙𝑙 =^𝑐^𝑢^𝑁^𝑐^𝑠_𝑓^𝑐^𝑑^𝑐^+𝑞

𝑠

𝑞_𝑎𝑙𝑙− 𝜎 = 0

Mz

M H

N

Natural Ground level (NGL)

Wf

e V R

(29)

19

𝐴_𝑒𝑓𝑓 𝑐 + 𝑉 𝑡𝑎𝑛 Ø 2𝑀_𝑧⁄𝑙_𝑒𝑓𝑓+√𝐻²+(2𝑀_𝑧⁄𝑙_𝑒𝑓𝑓)²

> 1

(30)

20

2𝑀_𝑧⁄𝑙_𝑒𝑓𝑓+√𝐻²+(2𝑀_𝑧⁄𝑙_𝑒𝑓𝑓)²

𝑉 < 0.4

Ø

(31)

21

D2

t D

(32)

22 a)

D

dfco ^θ Edge beam

Foundation base level t

b)

(33)

23

(34)

24

Soil Steel Cage

Movable load

a)

b)

c)

d)

(35)

25

(36)

26 Electric Valve M

M Electric Motor

(37)

27

The lower pipe system Motors rooms

Electric valve Electric pumps

(38)

28 a)

Wind direction

Soil

Steel Cage

Movable load

b)

(39)

29

a) b)

c) d)

(40)

30

0 5 10 15 20 25 30 35

14 16 18 20

Stabilising moment from the active system (MNm)

Raft Diameter (m)

0 5 10 15 20 25 30 35

14 16 18 20

Raft Diameter (m)

0 5 10 15 20 25 30 35

14 16 18 20

Raft Diameter (m)

Waggons filled with rock (30 kN/m³) Waggons filled with soil (22 kN/m³) Waggons filled with soil (19 kN/m³) Waggons filled with soil (16 kN/m³)

(41)

31

(42)

(43)

33

ϕ

ψ

Solid particles

Voids

Solid particles

Water

Solid particles

Air

Solid particles

Water Air

Saturated soil

Dry soil Partially saturated

soil Solid

particles Voids

Element separated into phases Soil

skeleton

(44)

34

No dilatancy,

dilatancy angle ψ = 0

ψ

Dilatancy during shear dilatancy angle ψ ≠ 0

(45)

35 e

log p’

Cc

Cs

1

1 Swelling line Consolidation Line

p

Time = 0 p = u p’ = 0

Time < ∞ p = u + p’

Time = ∞ p = p’

u = 0

a) b) c)

(46)

36

(47)

37

 ⁺ ^z

=E

Es so 1 0.06

𝐸 = 𝐸_𝑠^{1−𝑣−2𝑣}_1−𝑣 ² b)

z a)

(48)

38

a) b)

(49)

39 γ γ

∅ˋ

a) b)

(50)

40

(51)

41 ϕ

ψ

𝜎₁^,−𝜎₃^,

2 = 𝑐^,cos 𝜙^,+^𝜎¹^,^+𝜎₂ ³^, sin 𝜙^,

𝜎₁^, 𝜎₃^, 𝜎₁^, > 𝜎₃^,) ^̓

𝜙^,

𝜎₁^,−𝜎₃^, 2

σ’

σ₃’ τ

c'

c’ / tan ϕ (σ1’+σ₃’) / 2

ϕ'

(σ1’ - σ3’) / 2 Failure envelope

σ₁’

(52)

(53)

43

ν γ

(54)

44

(55)

(56)

46 a)

Wind direction

22.5˚ 45˚

(57)

47

θ

(58)

48

(59)

49

(60)

50

(61)

51

(62)

52

(63)

53 θ

(64)

54

(65)

55

(66)

(67)

57

(68)

58

(69)

59

(70)

60

(71)

61

(72)

62