Pile Design and Construction Practice, Fifth edition

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Miscellaneous piling problems 471 on shore as a single buoyant unit lowered on to the sea bed followed by driving piles through peripheral skirts in a manner similar to the piled foundations of offshore drilling platforms. Alternatively, the piles can be driven in the form of a raft with their heads projecting above a rock blanket or geotextile mattress. A prefabricated pier unit is then lowered over the pile group and the connection between the two formed by underwater concrete. The availability of heavy-lift cranes on barges or jack-up platforms favours this type of design. Prefabricated piers were used for 15 of the piers carrying the 3.3 km-long bridges between the islands of Sjaelland and Falster in Denmark. (9.37) A group of forty-nine 700 mm tubular steel piles in two concentric rings supported the deep-water piers in the navigable channel. The first operation was to form a level bed by dredging with protection against scour by rockfill. Then the piles were driven leaving their heads projecting about 6 m above the prepared bed (Figure 9.29). During these operations a precast reinforced concrete conical base unit weighing 440 tonne was being fabricated on shore. It was taken out to the pier site and lowered over the projecting pile heads on to three pinning piles. Concrete was then pumped into place under water to about mid-height of the base unit. The next operation was to lower a temporary circular steel cofferdam on to the top of the base unit to which it was locked by stressed rods. The cofferdam consisted of an assembly of steel plate rings 10 to 11 m in diameter and 3 m deep. The joints between the rings were sealed by rubber sheeting. This was followed by dewatering the cofferdam and constructing the pier, after which the cofferdam was flooded and lifted off the base unit by floating crane for transport to the next pier location. Permanent RC base unit Rockfill 1 in 3.3 1 in 5 10–11 m dia. Concrete placed under water 18.0 m dia. 700 mm OD � 9.5 mm WT steel tubular piles High water 3.0 m deep rings Pier constructed in cofferdam Temporary steel plate cofferdam Transition section Figure 9.29 Construction of deep-water piers for the Sjaelland–Faro–Falster Bridge, Denmark (after Levesque (9.37) ). 0.5 m 7.0 m Dredged sea bed
472 Miscellaneous piling problems 9.7 Piled foundations in karst The design and construction of piles for structures on land underlain by limestone formations which exhibit karst conditions such as wide fissures and solution cavities present several unique challenges. Because variations in rockhead and cavitation can occur over short distances it is difficult to produce an overall geological model of the site to determine if shallow foundations can be used or whether piles can be founded on ‘competent rock’. The first requirements are therefore to assess the depth and strength of the overburden, the extent of cavities and the degree of infilling under each foundation by drilling a series of closely spaced probe holes using a combination of rotary percussive rigs capable of installing casing and rotary coring drills. Waltham and Fookes (9.38) give an engineering classification of karst as a means of identifying foundation difficulties but they point out that there is no simple answer to the number of probes which may be required. The probes are usually taken to a depth of at least 3 m below rockhead and any void encountered, or to a similar depth below the anticipated depth of rock socket of each pile. Because of the possibility of vertical faces in the rockhead and cavities it is advisable to include a percentage of raked probe holes in the investigation. The selection of the pile installation method is critical, as it may be necessary to overcome random boulders in the overburden, remove and replace weak material in cavities through which the pile has to pass, and finally found on competent rock or form a socket in rock, ensuring that sound rock also exists within the bearing zone. Large driven piles are not usually feasible and the most effective method is the drilled and cast-in-place pile, usually with permanent steel casing sealed into the rock at the top of the socket. The removal of cavity and fissure infill debris and replacement with cement grout to allow uncased holes to be drilled for piles is expensive and rarely achieves the desired results. Flushing/grout holes are required at less than 1 m centres under and around the pile group and flushing water is necessary in quantities greater than 150 l per min and pressure greater than 10 bar – potentially causing pollution of surrounding water courses. If sufficient grout can then be injected it may be possible to place concrete in the open pile hole, or as temporary casing is withdrawn, without loss of fluid concrete. However, for pile diameters up to 1200 mm rotary-percussive rigs which can simultaneously install permanent casing (duplex drilling) are generally considered the most cost-effective installation method. For larger-diameter piles, the use of a powerful casing oscillator and a drilling method to clean out the pile and form the rock socket are recommended (see Section 3.3.2); above this diameter, shaft or caisson construction techniques may be necessary. Whichever method is used it is essential to probe below the base of the pile to check for cavities. Pile drilling may have to be continued until a sound bearing for the rock socket is located. Jet grouting could be used to consolidate any cavity infill within the bearing zone below the sound rock socket – again high grout pressure and volume (450 bar and 350 l per min) will be required with adequate venting to the surface and pollution control. Grouting to form a mattress of sound bearing material at rockhead for driven H-piles can be effective in karstic limestone (9.39) . In order to limit the flow of grout away from closely centred grout holes it was necessary in this case to vary the slump depending on injection rate and pressure and to use secondary and tertiary injection holes where grout loss occurred. Verifying the treatment is difficult and reliance has to be placed on detailed grouting records. Specially serrated driving shoes were needed to minimize the slipping of the pile tip along uneven bedrock surfaces to achieve full bearing capacity. ‘Micropiles’, with working capacity of 890 and 1160 kN, were used for bridge piers by inserting 245 mm diameter thick wall steel tubes into grout-filled pre-drilled holes as
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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
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where e is the height from the grou
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and Thus from Figure 6.24 deflectio
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(a) Deflection coefficient Ay (c) D
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(a) (b) (c) Depth coefficient Z 0 1
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Horizontal load H; Bending moment =
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Methods of drawing sets of p-y curv
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Calculations to determine the ultim
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(a) (b) Pressure Soil reaction p Ps
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Z�x/R 0 1.0 2.0 3.0 4.0 5.0 M(z)
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(a) yroGc H0 Ep Gc 1/7 (b) 0 0 0.1
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(a) determining the compressive and
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A X Z B R A Resultant R R B Y C D R
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6.8 FREEMAN, C. F., KLAJNERMAN, D.,
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Thus the load to be carried by anch
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If high-tensile steel (which has a
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sustained horizontal load which can
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Calculating the allowable horizonta
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Pile cap (Weight�2475 kN) F E D C
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The resultant of the vertical and h
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The Brinch Hansen bearing capacity
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Modulus of elasticity of pile � 2
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Chapter 7 Some aspects of the struc
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(a) (b) (c) Lifting rope Lifting po
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7.3 Designing piles to resist drivi
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Structural design of piles and pile
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should not arise if the piles are d
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(a) (b) (c) M.S.plate cover M.S.cap
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45˚ Structural design of piles and
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X Column Y9 Y9 Y Critical section f
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7.9 The design of pile capping beam
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Damp-proof course Cranked vent Grou
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(a) (b) Deck of wharf Fender Rubber
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(a) (b) y y e z f A The bending mom
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Piling for marine structures 403 th
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Pipe trunkways Hose handling platfo
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Piling for marine structures 407 8.
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Piling for marine structures 409 sh
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In SI units, equation 8.8 becomes f
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The natural frequency of the member
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The empirical equation of Korzhavin
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Piling for marine structures 417 re
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Table 8.3 Minimum safety factors fo
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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
Page 448 and 449: From �7.5 to �3.0 m: no increas
Page 450 and 451: Miscellaneous piling problems 435 W
Page 452 and 453: 9.2 Piling for underpinning Miscell
Page 454 and 455: Miscellaneous piling problems 439 B
Page 456 and 457: Miscellaneous piling problems 441 T
Page 458 and 459: Miscellaneous piling problems 443 p
Page 460 and 461: Longitudinal reinforcement is provi
Page 462 and 463: Light-gauge steel lining tubes Stow
Page 464 and 465: When inspecting the geological cond
Page 466 and 467: Miscellaneous piling problems 451 f
Page 468 and 469: natural ‘freeze-back’ around th
Page 470 and 471: Miscellaneous piling problems 455 b
Page 472 and 473: Miscellaneous piling problems 457 w
Page 474 and 475: Drainage layer 8.0 m 6.0 m Fill 1.0
Page 476 and 477: p m/c u 10.5 2p 0 and the mean hori
Page 478 and 479: Bridge abutment support piles Emban
Page 480 and 481: Figure 9.23 Drilling equipment for
Page 482 and 483: Max. water level +16 m Min. water l
Page 484 and 485: 2-4 m marine clay dredged out MHW R
Page 488 and 489: Miscellaneous piling problems 473 c
Page 490 and 491: The ground temperature around the p
Page 492 and 493: 9.40 URANOWSKI, D. D., DODDS, S., a
Page 494 and 495: The durability of piled foundations
Page 496 and 497: and European Standards as shown in
Page 500 and 501: martesia with some teredo, and at C
Page 512 and 513: economics, taking into account the
Page 514 and 515: Depth of borehole 1.5 B 1 in 4 B Gr
Page 516 and 517: Ground investigations, contracts an
Page 520 and 521: (a) DCP n (blows/100 mm) 40 35 30 2
Page 530 and 531: Table 11.2 Daily pile record for dr
Page 532 and 533: Paper fixed to pile by adhesive tap
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Ground investigations, contracts an
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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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