retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

70
1 Dr Youssef Hammida

Upload: dryoussef-hammida

Post on 07-Aug-2015

428 views

Category:

Technology


18 download

TRANSCRIPT

Page 1: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

1

Dr Youssef Hammida

Page 2: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

2

Page 3: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

3

Page 4: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

4

Page 5: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

5

Page 6: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

6

Page 7: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

7

Page 8: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

8

Page 9: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

9

Page 10: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

10

Page 11: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

11

Page 12: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

12

Page 13: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

13

Page 14: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

14

Page 15: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

15

Page 16: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

16

Page 17: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

17

Page 18: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

18

Page 19: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

19

Page 20: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

20

Page 21: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

21

Page 22: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

22

Page 23: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

23

Page 24: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

24

Page 25: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

25

Pilaster masonry wall

Page 26: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

26

Steel sheeting provides resistance during installation stresses. The sheets must be driven into the ground and they have high resistance to the force of being driven down.

It is extremely light weight and makes it easier to lift and handle. Steel sheeting is reusable and recyclable. There is a long life for it both above and under water. It only requires light

protection to keep it maintained. The pile length is easily adaptable and can be welded or bolted to make it

work. They have stronger joints that can withstand the force of being driven into

place.

Page 27: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

27

Steel Sheet Piling Construction Steps

First, lay out the sheets in sections to make sure that the piles will

interlock correctly.

Drive each sheet to the depth that has been mapped out.

Then drive the second sheet that has the interlocks between the first

sheet and the second locked sheet.

Repeat until the wall is completed.

If the wall requires complex shapes use connector elements to ensure

that the integrity of the wall is maintained.

Vibratory hammers are used for the installation of steel sheet piles.

An impact hammer is used if the soil is too dense for the vibratory

hammer.

At sites where vibrations are not recommended the sheets are pushed

into place using hydraulics.

Page 28: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

28

Page 29: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

29

Page 30: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

30

Page 31: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

31

Page 32: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

32

Page 33: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

33

Page 34: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

34

Page 35: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

35

-------------------------------------------------------

Page 36: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

36

Page 37: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

37

-----------------------------

Sheet Pile Walls...

Sheet pile walls are another method for construction of basements and

temporary excavations, however they are increasingly being used as

permanent structures with the correctly specified surface coating.

بيتم تنفيذها قبل حفر الموقع ألن وظيفتها سند جوانب الحفر الساندة واألوتاد, لخوازيقا يوم على تنفيذ آخر خازوق ساند 82واليتم الحفر قبل مرور

والخازوق الساند طوله مرتبط بقيمة الحفر واليصل لمنسوب تربة التأسيس

.

Page 38: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

38

Page 39: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

39

Page 40: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

40

For free earth support method

, the soils at the lower part of piling is incapable of inducing effective restraint so

that it would not result in negative bending moments. In essence, the passive

pressures in front of the sheet piles are insufficient to prevent lateral deflection

and rotations at the lower end of piling. No passive resistance is developed on

the backside of the piling below the line of excavation.

For fixed earth support method

, the piling is driven deep enough so that the soil under the line of excavation

provides the required restraint against deformations and rotations. In short, the

lower end of piling is essentially fixed.

Page 41: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

41

Anchored sheet pile wall

Anchored sheet pile wall in cohesionless soil Anchored sheet pile wall in cohesive soil

Design using free earth support method

1. Sheet pile is rigid, and lateral deflection is small. 2. The lateral pressure distributes according to Rankine’s or Coulomb’s theories

3. The tie back is strong, and sheet pile rotate about the tie rod anchor point at failure

4. Bottom of sheet pile is free to move.

Page 42: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

42

The embedded depth can be determined by summarizing horizontal earth pressures and moments about the anchor.

Fx = 0 [1]

Mo = 0 [2]

the lateral earth pressure is a function of embedded depth. Both equations are highly nonlinear. A trial and error method has to be used to determine the root.

For structural design, the sheet pile needs to be able to withstand maximum moment and shear from lateral pressure. A structural analysis needs to be done to determine

maximum moment and shear.

Page 43: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

43

Anchored sheet pile wall in cohesionless soil

Design length of sheet pile

Calculating active earth pressure

The method for calculating active earth pressure is the same as that in cantilever sheet pile wall. The lateral forces Ha1 is calculated as

Ha1= Ka h2/2+q Ka h

The depth a can be calculated as

a = pa / (Kp-Ka)

The lateral forces Ha2 can be calculated as

Ha2=pa*a/2

Calculating passive earth pressure

The slope from point C to E in the figure above is (Kp-Ka). The passive earth pressure at a depth Y below a is calculated as

Pp = (Kp-Ka) Y

Page 44: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

44

The passive lateral force

HCEF = (Kp-Ka) Y2/2

Derive equation for Y from Mo = 0

Mo = Ha1*y1 + Ha2* y2 – HCEF* y3 = 0

Where

y1 = (2h/3-b)

y2 = (h+a/3-b)

y3 = (h+a+2Y/3)

The equation needs to be determined by a trial and error process.

Determine anchor force T from Fx = 0

Fx = Ha1+ Ha2– HCEF-T = 0

Then,

T = Ha1+ Ha2– HCEF

Design size of sheet pile

The structural is the same as cantilever sheet piles in cohesionless soil.

Maximum moment locates at a distance y below T where shear stress equals to zero.

T- Ka (y+b)2/2=0

Solve for y, we have, y = -b+2*T/( Ka)

The maximum moment is

Mmax = T y - Ka (y+b)3/6

The required section modulus is S = Mmax / Fb

The sheet pile section is selected based on section modulus

Page 45: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

45

Design of tie rod and soldier beam

The sheet pile design above is based on a unit width, foot or meter. The tie back force T calculated from sheet pile design is force per linearly width of sheet pile. The top of

sheet pile often supported with soldier beams and tie rods at certain spacing.

Assume the spacing of tie rod is s, the tension in the rod is T times s. The required area of tie rod is

A = T s / Ft

Where Ft is allowable tensile stress of steel and is equal to 0.6Fy in AISC ASD design.

The soil beam is designed as a continuous beam that subjected to tie back force T. The maximum moment in the soldier beam is calculated from structural analysis. The

required section modulus is equal to S = Mmax / Fb.

Design procedure

1.Calculate lateral earth pressure at bottom of excavation, pa and Ha1.

pa = Ka H, Ha1=pa*h/2

2.Calculate the length a, and Ha2.

a = pa / (Kp-Ka), Ha2=pa*a/2

3.Assume a trial depth Y, calculate HCEF.

HCEF = (Kp-Ka) Y2/3

4.Let R = Ha1*y1 + Ha2* y2 – HCEF* y3

y1 = (2h/3-b)

Page 46: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

46

y2 = (h+a/3-b)

y3 = (h+a+2Y/3)

Substitute Y into R, if R = 0, the embedded depth, D = Y + a.

If not, assume a new Y, repeat step 3 to 4.

5.Calculate the length of sheet pile, L = h+F.S.*D, FS is from 1.2 to 1.4.

6.Calculate anchored force T = Ha1+ Ha2– HCEF

7.Calculate y = -b+2*T/( Ka)

8.Calculate Mmax = T y - Ka (y+b)3/6

9.Calculate required section modulus S= Mmax/Fb.

10. Select sheet pile section.

11. Design tie rod

12. Design soldier beam.

Page 47: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

47

Example 3. Design anchored sheet pile in cohesionless soil. Depth of excavation, h = 10 ft

Unit weight of soil, = 115 lb/ft3

Internal friction angle, = 30 degree

Allowable design stress of sheet pile = 32 ksi

Yield strength of soldier beam, Fy = 36 ksi

Location of tie rod at 2 ft below ground surface, spacing, s = 12 ft

Requirement: Design length of an anchored sheet pile, select sheet pile section, and design tie rod

Solution:

Design length of sheet pile:

Calculate lateral earth pressure coefficients:

Ka = tan (45-/2) = 0.333

Kp = tan (45-/2) = 3

The lateral earth pressure at bottom of excavation is

pa = Ka h = 0.333*115*10 = 383.33 psf

The active lateral force above excavation

Ha1 = pa*h/2 = 383.33*10/2 = 1917 lb/ft

The depth a = pa / (Kp-Ka) = 383.3 / [115*(3-0.333)] =1.25 ft

The corresponding lateral force

Ha2 = pa*a/2 = 383.33*1.25/2 = 238.6 lb/ft

Assume Y = 2.85 ft

HCEF = (Kp-Ka) Y2/3 = 115*(3-0.333)*2.852/3 = 830.3 lb/ft

y1 = (2h/3-b) = (2*10/3-2)=4.67 ft

y2 = (h+a/3-b) = (10+1.25/3-2)=8.42 ft

Page 48: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

48

y3 = (h+a+2Y/3) = (10+1.25+2*2.85/3) = 13.15 ft

R = Ha1*y1 + Ha2* y2 – HCEF* y3 = 1917*4.67+238.6*8.42-830.3*13.15 = 42.5 lb

R closes to zero, D = 2.85+1.25 = 4.1 ft

Length of sheet pile, L = 10 + 1.2* 4.1 = 14.9 ft Use 15 ft

Calculate anchor force,

T = Ha1+ Ha2– HCEF = 1917+238.6-830.3 = 1326 lb/ft

Calculate location of maximum moment,

y = -b+2*T/( Ka) = -2 ft + 2*1326/(115*0.333) = 6.32 ft

Mmax = T y - Ka (y+b)3/6 = 1326*6.32 – 115*0.333*(6.32+2)3/6 = 4.7 kip-ft/ft

The required section modulus S= Mmax/Fb = 4.7*12/32 = 1.8 in3/ft

Use PS28, S = 1.9 in3/ft

Design tie rod, the required cross section area,

A = T s / (0.6*Fy) = 1.326*12/(0.6*36) = 0.442 in3.

Use ¾” diameter tie rod, A = 0.442 in3.

Design soldier beam:

The maximum moment of a continuous beams with 3 or more span is

M = 0.1*T s2 = 0.1*1326*122 =19.1 kip-ft

Required section modulus, S = M / (0.6*Fy) = 19.1*12/(0.6*36) = 6.4 in3.

Use W6x15, S = 9.72 in3.

Page 49: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

49

Anchored sheet pile wall in cohesive soil.

Calculating active earth pressure

Calculation of active earth pressure above excavation is the same as that of cantilever

sheet pile in cohesive soil. The free-standing height of soil is d = 2C/

The lateral earth pressure at bottom of excavation, pa = h – 2C, where is unit weight of soil. The resultant force Ha=pa*h/2

Calculating passive earth pressure

For cohesive soil, friction angle, = 0, Ka = Kp = 1. The earth pressure below excavation,

p1= p-a= 2C-(h-2C) = 4C-h

Assume the embedded depth is D, the resultant force below bottom of excavation is

HBCDF = p1*D

Derive equation for D from Mo = 0

Mo = Ha1*y1 – HBCDF* y3 = 0

Where

y1 = 2(h-d)/3-(b-d)

y3 = h-b+D/2

The equation can be determined with a trial and error process.

Page 50: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

50

Determine anchor force T from Fx = 0

Fx = Ha1– HBCDF-T = 0

T = Ha1+ Ha2– HCEF

Design size of sheet pile

Maximum moment locates at a distance y below T where shear stress equals to zero.

T- Ka (y+b-d)2/2=0

Solve for y, we have, y = -b+d+2*T/( Ka)

The maximum moment is

Mmax = T y - Ka (y+b-d)3/6

The required section modulus is S = Mmax / Fb

The sheet pile section is selected based on section modulus

Design of tie rod and soldier beam

Design of tie rod and soldier beam is the same as that of anchored sheet pile in cohesionless soil.

1.Calculate free standing height, d = 2C/

2.Calculate pa=(h-d)

3.Calculate Ha=pa*h/2

4.Calculate p1=4C-h,

5.Assume a value of D, and calculate HBCDF = p1*D

6.Calculate R= Ha*y1 – HBCDF* y3.

Where

y1 = 2(h-d)/3-(b-d)

y3 = h-b+D/2

If R is not close to zero, assume a new D, repeat steps 5 and 6

7.The design length of sheet pile is L=h+D*FS, FS=1.2 to 1.4.

8.Calculate anchored force T = Ha – HBCDF

9.Calculate y = -b+d+2*T/

10. Calculate Mmax = T y - (y+b-d)3/6

11. Calculate required section modulus S= Mmax/Fb. Select sheet pile section.

Page 51: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

51

12. Design tie rod

13. Design soldier beam.

Example 4: Design anchored sheet pile in cohesive soil.

Depth of excavation, h = 15 ft

Unit weight of soil, = 115 lb/ft3

Cohesion of soil, C = 500 psf

Internal friction angle, = 0 degree

Allowable design strength of sheet pile = 32 ksi

Yield strength of soldier beam, Fy = 36 ksi

Location of tie rod at 2 ft below ground surface, spacing =12 ft.

Requirement: Design length of sheet pile and select sheet pile section

Solution:

Design length of sheet pile:

The free standing height, d = 2C/ = 2*500/115 = 8.7 ft

The lateral pressure at bottom of sheet pile, pa = (h-d)=115*(10-8.7)=150 psf

Total active force, Ha=pa*h/2 = 150*10/2 = 750 lb/ft

p1=4C-h = 4*550-115*15 = 275 psf

Assume D = 11.5 ft,

HBCDF = p1*D = 3163 lb/ft

y1 = 2(h-d)/3-(b-d) =2 (15-8.7)/3-(2-8.7) = 10.9 ft

y3 = h-b+D/2 = 15-2+11.5/2 = 18.75 ft

R= Ha*y1 – HBCDF* y3 = 5438*10.9-3163*18.75 = -36 lb Close to zero

The length of sheet pile, L = 15 + 1.2*11.5 = 28.8 ft Use 29 ft

Anchored force per foot of wall, T = Ha – HBCDF = 5438 – 3163 = 2275 lb/ft

Page 52: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

52

Calculate location of maximum moment,

y = -b+d+2*T/ = -2+8.7+2*2275/115 = 13 ft

Maximum moment,

Mmax = T y - (y+b-d)3/6 = 2275*13 – 115*(13+2-8.7)3/6 = 24770 lb-ft/ft

Required section modulus of sheet pile, S= Mmax/Fb = 22.47*12/32 = 8.4 in3/ft

Use PDA 27 section modulus 10.7 in3/ft

Design tie rod

Cross section of tie rod required, A = T*s/(0.6*Fy) = 2.275*12/(0.6*36) = 0.91 in2.

Diameter of tie rod, d = 4*A/ = 1.08 in

Use 1-1/8” diameter tie rod.

Design soldier beam

Maximum moment in solider beam, Mmax = 0.1*T*s2 = 0.1*2275*122 = 32760 lb-ft

Required section modulus, S= Mmax/Fb= 32.76*12/(0.6*36) = 13.1 in3.

Use W 8x18, section modulus S = 15.2 in3.

Page 53: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

53

types of deep support systems

are commonly used in metropolitan cities.

(i) Diaphragm walls

(ii) Pile walls (Contiguous, Tangent or Secant)

(iii) Soldier pile w

ith wooden lagging walls

(iv) Sheet pile walls

(v) Composite supporting systems – that is, any of the retaining

systems

Retaining systems like

diaphragm wall, contiguous pile walls;

and soldier piles with wooden lagging

described in this article has been successfully used. Case studies of their use indicate

that adequate quality control measures and instrumentation monitoring of

these systems go a long way in ensuring their safeand economic deployment at

sit

Page 54: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

54

Page 55: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

55

Page 56: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

56

Page 57: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

57

Page 58: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

58

Page 59: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

59

Contiguous Pile Walls General – Piled Retaining Systems

Abstract

Providing space for parking, public amenities,etc in multi-storey buildings at

town centres has created a need to go deep excavationsinto ground. Deep excavations

are supported by systems like conventional retaining walls, sheet pile walls,

braced walls, diaphragm walls and pile walls. This article describes various

excavation supporting systems that are in vogue essentially contiguous pile wall

and its advantages. A detailed design methodology of an excavation supporting

system is furnished in this study.

There are different types of pile walls

(Fig.4).Diameter and spacing of the piles is

decided based on soil type, ground water level and magnitude of design pressures.

Large spacing is avoided as it can result in caving of soil through gaps. In

Contiguous bored pile construction, center to center spacing of piles is kept slightly greater

thanthe pile diameter.

Secant bored pilesre formed by keeping this spacing of piles less

than the diameter.Tangen

Page 60: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

60

Fig. 4: Schematic Arrangement of Contiguous Piled Retaining System.

Contiguous piles serving as retaining walls

are popular since traditional piling equipments can be resorted for their construction. They

are considered more economical than diaphragm wall in small to medium scale excavations

due to reduction in cost of site operations. Common pile diameters adopted are 0.6, 0.8 and

1 .0m. These piles are connected with a Capping beams at the top, which assists equitable

pressure distributions in piles. These retaining piles are suitable in areas where water table is

deep or where soil permeability is low. However, some acceptable amount of water can be

collected at the base and pumped out.

ARRANGEMENT OF CONTIGUOUS PILe

Page 61: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

61

Page 62: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

62

Page 63: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

63

Secant Pile Walls are formedby constructing intersecting piles. Secant bored pile walls are formed by keeping spacing ofpiles lessthan diameter. Secant pile walls are used tobuild cut off walls for the control of groundwater inflow and to minimizemovement in weak and wet soils. Secant Wall constructed in the form of hard/soft or hard/firm and Secant Wall Hard/hard wall. Secant Wall-hard- softs or hard/firm is similar tothe contiguous bored pile wall

Page 64: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

64

Page 65: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

65

Page 66: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

66

Page 67: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

67

Soldier Piles and Wooden Lagging supported system

The supporting system comprised soldier piles

spaced at 1.8m c/c and with a closer spacing of 1.6m c/c near the launching shaft (Fig.8). Wooden laggings of thickness 100mm to 120mm were supported between the soldier piles.Three levels of Struts were provided at depths 3.285, 7.285, and 10.831m below the established ground level (EGL-209.80m). Additional level of Waler beam with pre-stressed rock anchors were provided 2m above the excavation level. Rock anchors with capacity of 86.4T,spaced at 3.6m c/c, were embedded 6m into the quartzitic bedrock to meet the bond strength consideration

Page 68: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

68

Soldier Piles & Laggings Wooden Supporting System

Page 69: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

69

Page 70: Retaining walls (الجدران الاستنادية)-steel sheet piles - sheet piles wall

70

Dr Youssef Hammida