Pile Design and Construction Practice, Fifth edition

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Structural design of piles and pile groups 383 A heavier hammer can be used to achieve the necessary penetration but this may involve a risk of overstressing the pile. 7.4 The effects on bending of piles below ground level Slender steel tubular piles and H-piles may deviate appreciably off line during driving. These effects were described in Section 2.2.4 where it was noted that, whereas the ill-effects of bending or buckling of tubular piles below ground level could be overcome by inserting a reinforcing cage and filling the pile with concrete, such a procedure could not be adopted with H-piles. Therefore, where long H-piles are to be driven in ground conditions giving rise to bending or buckling, a limiting value must be placed on their curvature. It is not usual to take any special precautions against the deviation of reinforced concrete piles other than to ensure that the joints between elements of jointed pile systems (see Section 2.2.3) are capable of developing the same bending strength as the adjacent unjointed sections. Reinforced concrete piles without joints cannot in any case be driven to very long lengths in soil conditions which give rise to excessive curvature. It is, of course, possible to inspect hollow prestressed concrete piles internally and to adopt the necessary strengthening by placing in-situ concrete if they are buckled. It is impossible to drive a pile with a sufficient control of the alignment such that the pile is truly vertical (or at the intended rake) and that the head finishes exactly at the designed position. Tolerances specified in various codes of practice are given in Section 3.4.12. If the specified deviations are exceeded, to an extent detrimental to the performance of the piles under working conditions, the misaligned piles must be pulled out for redriving or additional piles driven. Calculations may show that minor excesses from the specified tolerances do not cause excessive bending stresses as a result of the eccentric loading. In the case of driven and cast-in-place or bored and cast-in-place piles it may be possible to provide extra reinforcement in the upper part of the pile to withstand these bending stresses. For this reason Fleming and Lane (7.6) recommend that checks on the positional accuracy of in-situ forms of piling should be made before the concrete is placed. The methods described in Section 6.3.9 can be used to calculate the bending stresses caused by eccentric loading. The effect of the deviation is expressed as a bending moment Pe, where the load P deviates by a distance e from the vertical axis of the pile. 7.5 The design of axially loaded piles as columns Buckling of axially loaded piles terminating at ground level in a pile cap or ground beam cannot occur if the piles are loaded to within the permissible working stresses on the pile material. Thus such piles need not be considered as long columns for the purpose of structural design. However, it is necessary to consider the column strength of piles projecting above the soil line, as in jetties or piled trestles. BS 8004 recommends that the depth below ground surface to the point of contraflexure should be taken as 1 m in firm ground and as much as one-half of the penetration depth but not necessarily more than 3 m in a weak ground such as soft clay or silt. A stratum of liquid mud should be treated as if it were water. The column strength of the pile is then calculated as for a short column and a reduction factor is applied to the calculated ultimate load to allow for the slenderness of the column, where the slenderness is defined as the ratio of the effective length to the breadth or radius of gyration.
384 Structural design of piles and pile groups Effective lengths for reinforced concrete piles when regarded as columns are defined by EC2 (Clause 5.8.3.2): Restrained at both ends in position and direction: 0.5 L Restrained at both ends in position and one end in direction: 0.7 L Restrained at both ends in position but not in direction: 1.0 L Restrained at one end in position and direction and at the other end in direction but not in position: 1.0 L Restrained at one end in position and direction and free at the other end: 2.0 L EC3 (BS EN 1993-1-1: 2005) is currently silent on effective lengths for steel piles when regarded as columns, requiring the application of the guidance given in BS 5950 part 1, which is slightly different from the above factors. A pile embedded in the soil can be regarded as properly restrained in position and direction at the point of virtual fixity in the soil. The restraint at the upper end depends on the design of the pile cap and the extent to which the pile cap is restrained against movement by its connection with adjacent pile caps or structures. Some typical cases of the restraint of piles are shown in Figure 7.4a to e. The condition shown in Figure 7.4e Tie beams holding pile cap in position Hard rock (a) (b) Cable anchors Soft clay Raking piles in four directions (c) (d) (e) Tie beams holding pile cap in position Figure 7.4 Conditions of restraint for vertical piles (a) Restrained at top and bottom in position and direction (b) Restrained at bottom in position and direction; restrained at top in position but not in direction (c) Restrained at top and bottom in position but not in direction (d) Restrained at bottom in position and direction; restrained at top in direction but not in position (e) Restrained at bottom in position and direction; unrestrained at top in position or direction.
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Pile Design and Construction Practi
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Pile Design and Construction Practi
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Contents Preface to fifth edition i
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7.3 Designing piles to resist drivi
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Preface to fifth edition Piling rig
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Preface to fifth edition xi Pearson
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Chapter 1 General principles and pr
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(a) Backfill Bulb of pressure Appli
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are allowed to be used by Eurocode
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application of different load facto
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Load transfer The contractor’s gu
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(7) Jacked-down steel tube with clo
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Types of pile 13 needed to avoid cr
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(a) (b) Precast concrete Head of ti
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Table 2.2 Modification factor K 2 b
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4d d 10 mm M.S. plate sleeve tarred
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Table 2.3 Working loads and maximum
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Cement content �300 kg/m3 �325
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Types of pile 25 Table 2.5 BS 8004
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(a) (b) (c) (d) Cast iron or cast s
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Sheathing Bottom boards Figure 2.9
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Misplaced bearers Lifting holes Cra
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Section Bayonet plug Plan Locking p
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Existing foundation Precast pile ca
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Types of pile 37 Where very long le
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Types of pile 39 rotate during driv
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Types of pile 41 Because of their r
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(a) (b) Types of pile 43 Figure 2.2
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(a) (b) Welds Welds Types of pile 4
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(a) M.S. plate shoe Welds (b) 2.2.6
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Types of pile 49 brittle fracture r
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(a) (b) (c) Hammer Driving tube Con
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Types of pile 53 all cast-in-place
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Figure 2.28 The TaperTube pile.
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(a) (b) Figure 2.29 (a) The ScrewSo
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Types of pile 59 The simplest form
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Types of pile 61 Transverse reinfor
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Types of pile 63 completion the res
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Types of pile 65 permanently in the
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Types of pile 67 (3) Construction o
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Types of pile 69 can withstand fair
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Chapter 3 Piling equipment and meth
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Piling equipment and methods 73 A r
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Maximum height 26.32 m Usable leade
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Figure 3.4 Liebherr LRH 400 48 m lo
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Piling equipment and methods 79 the
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Piling frame Single-acting hammer S
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Guides for engaging leaders Steam o
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Table 3.1 Characteristics of some s
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Table 3.2 Characteristics of some h
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Piling equipment and methods 89 Tab
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Table 3.4 Characteristics of some d
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Figure 3.16 Driving a pile casing w
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Table 3.5 Continued Piling equipmen
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Soil resistance to driving (MN) 25
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Figure 3.19 Noise-abatement tower u
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Dolly M.S. plate Plastics Hardwood
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Standard elbow bend Detachable scre
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Figure 3.24 Discharging concrete in
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Piling equipment and methods 107 Fi
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Table 3.6 Continued Piling equipmen
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Figure 3.30 Top-hinged under-reamin
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Rotary table Hydraulic motor Water
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Piling equipment and methods 121 sl
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Pile head Pile base 2 holes ∅ 4 m
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Piling equipment and methods 125 Ca
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Piling equipment and methods 127 sm
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Piling equipment and methods 131 Th
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Piling equipment and methods 133 th
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Piling equipment and methods 135 Pi
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Piling equipment and methods 137 ve
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Chapter 4 Calculating the resistanc
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O C Settlement A Reloading Load B U
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Resistance of piles to compressive
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for spread foundations in various c
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structural actions and A2 to geotec
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Geometrical data are concerned with
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Figure 4.3 Failure surfaces for com
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Depth below ground level in m 5.6 1
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(a) (b) Peak adhesion factor a p Le
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orehole or test profile over the pe
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Effective length Shaft friction not
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4.3 Piles in coarse-grained soils 4
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Depth below ground surface (m) Resi
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Depth of penetration (m) 0 0 5 10 1
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using standard penetration tests or
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� � Resistance of piles to comp
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Safety factors generally used in th
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Depth to NAP datum (m) Cone resista
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The conditions at the interface can
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The shear modulus G in equation 4.3
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2.0 OD tubular steel pile with clos
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where Resistance of piles to compre
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eached the point of ultimate resist
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(4) Obtain the safe end-bearing loa
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Vertical force, t t-z curve Vertica
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where the bearing capacity factor:
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and RQD of the rock as shown in Tab
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Depth below ground level (m) 0 5 10
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settlement of the pile are summariz
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Rock socket reduction factor a 1.0
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Table 4.17 � and � values of we
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Influence factor, l p 2.0 1.6 1.2 0
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(a) (b) No load on pile head Residu
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a closed end into a deep deposit of
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Average shearing strength along pil
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It is assumed that the shear streng
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Depth below ground level (m) Figure
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Figure 4.45 Depth below ground leve
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Depth of h(m) Segment (m bql) � h
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For a wall thickness of 19 mm in mi
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Pile groups under compressive loadi
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24.0 m 16.0 m The comparative group
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where c � cohesion intercept of s
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Inclination factor, i c Inclination
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z/B 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
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Compressive stress 1.5 q n q n B A
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E u/c u 3000 2500 2000 1500 1000 50
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0 0 1 2 3 4 H/B 5 6 7 8 9 0 1 2 3 4
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D LB LB D 0.50 0 0.1 0.2 0.3 0.4 0.
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Initial tangent constrained modulus
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factor N for which Schmertmann sugg
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0 0 2 4 H/B 6 8 10 Influence factor
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Overall loading 100 kN/m2 (a) (b) (
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(a) (b) (c) (d) Pile groups under c
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Depth below ground level in m 5 10
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For the arrangement of the piles sh
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Soft clay Sand B/2 5 11.2 m Figure
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Unit negative skin friction at top
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Chapter 6 The design of piled found
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(a) Tie rod Wholly compression Whol
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esistance of cylindrical augered fo
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in the ground is assumed to be equa
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Section 3.3.1. Enlargements cannot
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Piles to resist uplift and lateral
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Spacer Top of hard rock Drilling pi
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where m is the modular ratio of ste
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Table 6.3 Examples of bond stress b
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Top of rock 30˚ 30˚ Figure 6.15 F
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(b) P/n & �Vm Vc 2.0 1.8 1.6 1.4
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Table 6.4 Partial resistance factor
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and adjustment, starting with a ver
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Coefficient of subgrade modulus var
Page 348 and 349: where e is the height from the grou
Page 350 and 351: and Thus from Figure 6.24 deflectio
Page 352 and 353: (a) Deflection coefficient Ay (c) D
Page 354 and 355: (a) (b) (c) Depth coefficient Z 0 1
Page 356 and 357: Horizontal load H; Bending moment =
Page 358 and 359: Methods of drawing sets of p-y curv
Page 360 and 361: Calculations to determine the ultim
Page 362 and 363: (a) (b) Pressure Soil reaction p Ps
Page 364 and 365: Z�x/R 0 1.0 2.0 3.0 4.0 5.0 M(z)
Page 366 and 367: (a) yroGc H0 Ep Gc 1/7 (b) 0 0 0.1
Page 368 and 369: (a) determining the compressive and
Page 370 and 371: A X Z B R A Resultant R R B Y C D R
Page 372 and 373: 6.8 FREEMAN, C. F., KLAJNERMAN, D.,
Page 374 and 375: Thus the load to be carried by anch
Page 376 and 377: If high-tensile steel (which has a
Page 378 and 379: sustained horizontal load which can
Page 380 and 381: Calculating the allowable horizonta
Page 382 and 383: Pile cap (Weight�2475 kN) F E D C
Page 384 and 385: The resultant of the vertical and h
Page 386 and 387: The Brinch Hansen bearing capacity
Page 388 and 389: Modulus of elasticity of pile � 2
Page 390 and 391: Chapter 7 Some aspects of the struc
Page 392 and 393: (a) (b) (c) Lifting rope Lifting po
Page 394 and 395: 7.3 Designing piles to resist drivi
Page 396 and 397: Structural design of piles and pile
Page 400 and 401: should not arise if the piles are d
Page 402 and 403: (a) (b) (c) M.S.plate cover M.S.cap
Page 404 and 405: 45˚ Structural design of piles and
Page 406 and 407: X Column Y9 Y9 Y Critical section f
Page 408 and 409: 7.9 The design of pile capping beam
Page 410 and 411: Damp-proof course Cranked vent Grou
Page 412 and 413: Structural design of piles and pile
Page 414 and 415: (a) (b) Deck of wharf Fender Rubber
Page 416 and 417: (a) (b) y y e z f A The bending mom
Page 418 and 419: Piling for marine structures 403 th
Page 420 and 421: Pipe trunkways Hose handling platfo
Page 422 and 423: Piling for marine structures 407 8.
Page 424 and 425: Piling for marine structures 409 sh
Page 426 and 427: In SI units, equation 8.8 becomes f
Page 428 and 429: The natural frequency of the member
Page 430 and 431: The empirical equation of Korzhavin
Page 432 and 433: Piling for marine structures 417 re
Page 434 and 435: Table 8.3 Minimum safety factors fo
Page 436 and 437: Piling for marine structures 421 th
Page 438 and 439: Piling for marine structures 423 sh
Page 440 and 441: 8.21 GERWICK, B. C. Construction of
Page 442 and 443: Soil resistance p in kN per m of de
Page 444 and 445: From Figures 6.29a and b the comput
Page 446 and 447: giving 9.7y � 0.26, y � 0.26
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From �7.5 to �3.0 m: no increas
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Miscellaneous piling problems 435 W
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9.2 Piling for underpinning Miscell
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Miscellaneous piling problems 439 B
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Miscellaneous piling problems 441 T
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Miscellaneous piling problems 443 p
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Longitudinal reinforcement is provi
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Light-gauge steel lining tubes Stow
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When inspecting the geological cond
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Miscellaneous piling problems 451 f
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natural ‘freeze-back’ around th
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Miscellaneous piling problems 455 b
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Miscellaneous piling problems 457 w
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Drainage layer 8.0 m 6.0 m Fill 1.0
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p m/c u 10.5 2p 0 and the mean hori
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Bridge abutment support piles Emban
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Figure 9.23 Drilling equipment for
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Max. water level +16 m Min. water l
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2-4 m marine clay dredged out MHW R
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Miscellaneous piling problems 471 o
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Miscellaneous piling problems 473 c
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The ground temperature around the p
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9.40 URANOWSKI, D. D., DODDS, S., a
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The durability of piled foundations
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and European Standards as shown in
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martesia with some teredo, and at C
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economics, taking into account the
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Depth of borehole 1.5 B 1 in 4 B Gr
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Ground investigations, contracts an
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(a) DCP n (blows/100 mm) 40 35 30 2
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Table 11.2 Daily pile record for dr
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Paper fixed to pile by adhesive tap
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Figure 11.10 Patented arrangement f
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following expressions: (11.1) Load
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(b) Settlement of pile head in mm S
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(a) Settlement � (mm) 0 0 4 8 Gro
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experience to give reasonably relia
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Appendix Properties of materials A.
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Subdivisions of Grades A to C chalk
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544 Name index Davis, E. H. 354 Dav
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546 Name index Schaaf, S. A. 424 Sc
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548 Subject index contiguous piles
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550 Subject index Pali Radice piles
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Pile Design and Construction Practice, Fifth edition

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