piled foundation - pile capacity - skin resistance (q ) - sand · 31 * das (2016), principles of...

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Sand

31 * Das (2016), Principles of Foundation Engineering, 8th edition

Michael Tomlinson and John Woodward (2008), Pile Design and Construction Practice.

High-displacement driven = Large displacement piles

Low-displacement driven = Small displacement pilesBored or jetted = Replacement pilesCoyle and Castello (1981)

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Sand

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High displacement driven piles

Low displacement driven piles

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Sand - SPT

33 * Das (2016), Principles of Foundation Engineering, 8th edition

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Sand - CPT

34 * Das (2016), Principles of Foundation Engineering, 8th edition

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Sand - Example

* Das (2016), Principles of Foundation Engineering, 8th edition

= 6.1 m

f (z = 0) = 0

f (z = 6.1) = 75.9

f ( 6.1 < z < 20) = 75.9 constant (= 75.9) from 6.1 m to 20 m

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Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Sand - Example

* Das (2016), Principles of Foundation Engineering, 8th edition

40

50

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≃ 0.4

by projection

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Sand - Example

37 * Das (2016), Principles of Foundation Engineering, 8th edition

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Sand - Example - CPT

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Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Clay - Lamda (𝜆)

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Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Clay - Alpha (𝛼)

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Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Clay - Alpha (𝛼)0.25

This is shown graphically in Figure 9.21. For cuy !o9 $ 1,

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Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Clay - Beta (𝛽)

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Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Clay - Example

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cupa

= 0.25

cupa

= 0.4

cupa

= 0.9

↵ = 0.87

↵ = 0.51

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Clay - Example

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Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Clay - Example

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442 Chapter 9: Pile Foundations

Example 9.7Refer to the pipe pile in saturated clay shown in Figure 9.24. For the pile,

a. Calculate the skin resistance sQsd by (1) the ! method, (2) the " method, and (3) the # method. For the # method, use $R9 5 308 for all clay layers. The top 10 m of clay is normally consolidated. The bottom clay layer has an OCR 5 2. (Note: diameter of pile 5 457 mm)

b. Using the results of Example 9.2, estimate the allowable pile capacity sQalld. Use FS 5 4.

SolutionPart a(1) From Eq. (9.59),

Qs 5 o!cu pDL

Table 9.13 Typical Values of Angle of Friction $9 of Rocks

Type of rock Angle of friction, f9 (deg)

Sandstone 27–45Limestone 30–40Shale 10–20Granite 40–50Marble 25–30

Groundwatertable

A1 5 72

A2 5 512.16

A3 5 1392.8

z

(a) (b)20 m 180.23

98.3310 m

3 m48

!9o (kN/m2)

3 mSaturated clay

Clay7 m

10 m

Diameter 5457 mm

cu(2)"sat

5 40 kN/m2

5 17 kN/m3

cu(1)"

5 25 kN/m2

5 16 kN/m3

Claycu(3)"sat

5 90 kN/m2

5 18 kN/m3

Figure 9.24 Estimation of the load bearing capacity of a driven-pipe pile

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a MethodAccording to the

Piled Foundation - Pile Capacity - Skin Resistance (Qs) - Clay - Example

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Piled Foundation - Pile Capacity - Skin Resistance (Qs) - CPT

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Piled Foundation - Pile Capacity - Qp - Rock

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Piled Foundation - Pile Capacity - Negative Skin Friction

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Piled Foundation - Pile Capacity - Negative Skin Friction

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Piled Foundation - Pile Capacity - Negative Skin Friction - Example

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Piled Foundation - Pile Capacity - Negative Skin Friction - Example

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Piled Foundation - Group Piles - Group Efficiency

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Piled Foundation - Group Piles - Group Efficiency

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Piled Foundation - Group Piles - Group Efficiency

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Piled Foundation - Group Piles - Group Efficiency

lb to kip in to feet

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Piled Foundation - Group Piles - Group Efficiency

8 8.57

8.75