sheet pile types

8/12/2019 Sheet Pile Types

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Sheet Pile Structures

Depending on the way the retaining structure is built and analyzed, it can be divided

into three categories:

1.

Cantilever Sheet Pile2. Anchored Sheet Pile

3. Braced Sheet Pile

Cantilever Sheet Pile



Case 1 (Sheet Pile Penetrating Sandy Soils)

A few key points that define the lateral earth pressure in Figure 8.7:

1.

Point A to Point D (p1): Active earth pressure on the right hand side.2. Point D to Point H (p3): (Passive earth pressure on the left hand side) - (Active

earth pressure on the right hand side).

3. Point G (p4): (Passive earth pressure on the right hand side) - (Active earth

pressure on the left hand side).

4. Point E (L3): Can be determined from equation derived in 2.

5. Point F (L5): To be determined.

Unknowns: D and L5

Equations: 0 xF

0 B M

The actual depth of penetration is increased by 20%~30% for construction.

To calculate maximum bending moment:

1. Determine point of zero shear force: let P (area of ACDE) = Shaded area E-F”

2. Moment can be determined at the section of zero shear force.



Case 2 (Sheet Pile Penetrating Clay)

A few key points that define the lateral earth pressure in Figure 8.7:

1. Point A to Point D (p1): Active earth pressure on the right hand side.

2. Point F to Point I (p6): (Passive earth pressure on the left hand side) - (Active earth

pressure on the right hand side).

3. Point G (p7) : (Passive earth pressure on the right hand side) - (Active earth

pressure on the left hand side).

4. Point E (L3): Can be determined from equation derived in 2.

5. Point G (L4): To be determined

Unknowns: D and L4

Equations: 0 xF

0 B M

To calculate maximum bending moment:

1. Determine point of zero shear force

2. Moment can be determined at the section of zero shear force.



Case 1. (Free earth support method for penetration of sandy soil)

Unknowns: D and T

Equations: 0 xF

0 o M

The actual depth of penetration is increased by 30%~40% for construction.



Anchors



Ultimate Resistance of Tiebacks

In Sand:

tan' K dlP vu

K = K 0 if the concrete grout is placed under pressureLower limit of K is Rankine K a

In Clay:

au dlcP

ca = adhesion ≈ uc3

2

Factor of Safety = 1.5-2.0 may be used over ultimate resistance to obtain the

allowable resistance offered by each tieback.



Braced Cut

To avoid considerable settlement or bearing capacity failure of nearby structure.

To prevent water seepage into excavation

Pressure Envelop for Braced Cut Design

The struts limit lateral wall movement, K a not mobilized, P > Pa by 10% ~15%.

After observation of several braced cuts, Peck (1969) suggested using design pressure

envelops (apparent pressure envelop)

h/cu > 4 h/cu < 4

0.3 H



Limitations:

1. Pa may depend on construction sequence.

2. They apply when H about 6 m.

3. G.W.T. below the bottom of excavation

4. Sand is drained (uw =0)

5. Clay is undrained (uw not considered)

Cuts in Layered Soil

Case (a)

ucssssav C n H H K H

C 'tan2

11 2

K s = K for sand layer ( 1)

n' = a coefficient of progressive failure, 0.5 ~1.0, average 0.75.

Case (b)

2211

1 H C H C

H C av

2211

1 H H

H av



Stability of Open Cut

Bottom Heaving of a Cut in Clay

2.17.5

1

1

H C HB

BC FS

u

u

5.1'

"2.0114.5

q H

B

H C

L

BC

FS

u

u

B’ = T if T B / 2 ; B’ = B / 2 if T > B / 2 ;

B” = 2 B’

Chang (2000)

Terzaghi (1943)



Piping of a Cut in Sand

5.1)max(

exit

cr

i

iFS

Uplifting of a Cut in Inter-Layer

2.1)( 1

1 ww

sat

H H H FS

Depth of Penetration

5.1

saa

p p

M lP

lPFS

H1

Uf = H1+Hw

Impervious

lp P p Pa

la



Global Stability of Anchored Sheet Pile

5.1o

r

M

M FS

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