Civil Engineering Project Management (4th Edition)

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18 Earthworks and pipelines 18.1 Excavating and earth-placing machinery Bulldozers (‘dozers’) are used for cutting and grading work, for pushing scrapers to assist in their loading, stripping borrowpits, and for spreading and compacting fill. The larger sizes are powerful but are costly to run and maintain, so it is not economic for the contractor to keep one on site for the occasional job. Its principal full-time use is for cutting, or for spreading fill for earthworks in the specified layer thickness and compacting and bonding it to the previously compacted layer. It is the weight and vibration of the dozer that achieves compaction, so that a Caterpillar ‘D8’ 115 h.p. weighing about 15 t, or its equivalent, is the machine required; not a ‘D6’ weighing 7.5 t which is not half as effective in compaction. The dozer cannot shift material very far, it can only spread it locally. A dozer with gripped tracks can climb a 1 in 2 slope, and may also climb a slope as steep as 1 in 1.5 provided the material of the slope gives adequate grip and is not composed of loose rounded cobbles. On such slopes of 1 in 1.5 or 1 in 2 the dozer must not turn, but must go straight up or down the slope, turning on flatter ground at the top and bottom. It is dangerous to work a dozer (and any kind of tractor) on sidelong ground, particularly if the ground is soft. Dozers cannot traverse metalled roads because of the damage this would cause, and they should not be permitted on finished formation surfaces. Sometimes a flat tracked dozer (i.e. with no grips to the tracks) can be used on a formation if the ground is suitable. Motorized scrapers are the principal bulk excavation and earth-placing machines, used extensively on road construction or earth dam construction. Their movement needs to be planned so that they pick up material on a downgrade, their weight assisting in loading; if this cannot be managed or the ground is tough, they may need a dozer acting as a pusher when loading. This not only avoids the need for a more expensive higher powered scraper, but reduces
226 Civil Engineering Project Management the wear on its large balloon tyres which are expensive. The motorized scraper gives the lowest cost of excavation per cubic metre of any machine, but it needs a wide area to excavate or fill and only gentle gradients on its haul road. It cannot excavate hard bands or rock, or cut near-vertical sided excavations. The face shovel, or ‘digger’ can give high outputs in most types of materials, including broken rock. It comes in all sizes from small to ‘giant’; but for typical major excavation jobs (such as quarrying for fill) it would have a relatively large bucket of 2–5 m 3 capacity. The size adopted depends on what rate of excavation must be achieved, the capacity of dump trucks it feeds to cart away material, and the haul distance to tip or earthworks to be constructed. The face shovel would normally be sized to fill a dump truck in only a few cycles. The machine can only excavate material down to its standing level, and work a limited height of excavation face. Hence, if a deep excavation is required, the face shovel must ‘bench in’ and must leave an access slope for getting out when it has finished excavating. It must stand on firm level ground when working, and is not very mobile. It works in one location for as long as required, moving its position only as excavation proceeds. Its major advantage is its high output and ability to excavate in most materials. The hydraulic excavator used as a hoe or backacter, cuts towards the machine. It is highly versatile. The larger sizes can cut to a depth of 6 or 7 m and excavate a face of the same height, slewing to load to trucks alongside. It can be used for lifting pipes into trenches, and ‘bumping down’ loose material in the base of a trench with the underside of its bucket. It can usually excavate trenches in all materials except rock; but sometimes has trouble in getting out hard bands of material that are horizontally bedded or which dip away from the machine. It can have a toothed bucket capable of breaking up a stony formation, or be fitted with a ripper tooth for soft rock or a hydraulic breaker for hard materials, or have a smooth edged bucket for trimming the base of a trench. A wide range of such machines are available, the smallest size often being used on small building sites; the larger sizes being used for large trench excavation and general excavation of all kinds. The dragline’s principal use is on river dredging work from the bankside, and for other below water excavation. Although the machine is slow in operation and has a smaller rate of output than an equivalent hydraulic backhoe, it can have a long reach when equipped with a long jib and can excavate below its standing level. With a 15-m jib, it can throw its bucket 20–25 m out from the machine; hence its use for river bed excavation and bankside trimming. The dragline can also be operated to cut and grade an embankment slope below its standing level, or for dumping soil or rock on such a slope. A trained operator can be skilled at placing the bucket accurately to a desired position. The dragline offloads its material to dump trucks, but this tends to be a messy operation because the swing of the bucket on its suspension cable tends to scatter material. The wheeled loader is widely used for face excavation in soft material, but its predominant use is for shifting heaps of loose spoil and loading them to lorries. It may have a bucket size of up to 5 m 3 ; it is very mobile and, being soft tyred, can traverse public roads.
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Civil Engineering Project Managemen
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Civil Engineering Project Managemen
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Contents Preface xiii Acknowledgeme
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Contents vii 4.3 Conditions publish
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Contents ix 10.3 The Health and Saf
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Contents xi 15.4 Problems with clas
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Preface Most civil engineering cons
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1 The development of construction p
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The great majority of all civil eng
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and takes over ownership of them at
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The development of construction pro
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supported by the DETR’s 7 Constru
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advantage is that a contractor who
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civil engineering, incorrect or ins
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The development of construction pro
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2 Procedures for design and constru
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2.3 Options for design The followin
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utilities in the UK continued to us
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Some plant suppliers, however, will
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• The promoter may need to employ
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given period of a year or longer. T
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3 Payment arrangements, risks and p
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(c) Lump sum contracts Payment arra
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inflation of prices after he has te
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Payment arrangements, risks and pro
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Payment arrangements, risks and pro
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if not, to make some deletion to re
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Contract conditions used for civil
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D&C contracts are often used when t
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4.3 Conditions published by the Int
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authorities. A range of standard fo
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Contract conditions used for civil
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5.2 Roles of the key participants i
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Preparing contract documents 53 the
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Preparing contract documents 55 mat
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work. Some methods may need to be s
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personnel may also be included. Thi
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Preparing contract documents 61 hen
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Preparing contract documents 63 ‘
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invited to bid for the project. Con
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Tendering 67 If pre-qualification i
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construction, so that they can plan
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e avoided because they can provide
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corrected. Where this results in an
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6.8 Choosing a tender Tendering 75
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Tendering 77 • an intent that the
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Appendix: UK Regulations UK Statuto
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execution of the contract, but he d
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of formwork carpenters, steel erect
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The contractor’s site organizatio
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The contractor’s site organizatio
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8.1 Introduction 8 The employer and
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8.3 A note on alternative provision
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further drawings the contractor nee
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(see References 5 and 6). But under
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The resident engineer’s duties 97
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need to go carefully at first so th
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10 Health and safety regulations 10
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Health and safety regulations 109 N
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10.5 Training As part of the drive
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should be evaluated. This is a new
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10.9 The Construction (Health, Safe
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Health and safety regulations 117 C
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enable first aid to be given to emp
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• The programme for construction
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• rainfall and runoff data; • d
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Starting the construction work 125
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Starting the construction work 127
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12.2 Levelling Site surveys, invest
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each floor. Alternatively an optica
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instance, it will have to be starte
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Percussion drilling Site surveys, i
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For grading analyses of soils 4. A
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Site surveys, investigations and la
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Contract state that the employer wi
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The drainage of clay or clay and si
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General files (Series 1-9) The resi
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If an instruction does not vary the
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The resident engineer’s office re
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13.8 Authorization of dayworks The
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with the engineer. If the decision
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Fig. 13.7. A page of a pipe stock b
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in red on a copy of the contract dr
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14 Programme and progress charts 14
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how any consequential delay to the
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Description EXC. & filling soil str
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Programme and progress charts 171 d
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Height A.O.D. 200m 100m Pumping sta
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Page 192 and 193: Table 14.1 Estimated Final Cost of
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Page 212 and 213: Interim monthly payments 197 28 day
Page 214 and 215: Interim monthly payments 199 paid t
Page 216 and 217: Interim monthly payments 201 into d
Page 218 and 219: or for which contractual dates for
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Page 222 and 223: Variations and claims 207 reaching
Page 224 and 225: Variations and claims 209 Extensive
Page 226 and 227: The problem of setting rates for ne
Page 228 and 229: Variations and claims 213 that the
Page 230 and 231: costs. The problem is that borings
Page 232 and 233: 17.10 Delay claims Variations and c
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Page 238 and 239: 17.16 Arbitration Under the ICE con
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Page 244 and 245: match the timing of empty vehicles
Page 246 and 247: are then more clearly revealed. The
Page 248 and 249: minimum rise or fall. The preferred
Page 250 and 251: Earthworks and pipelines 235 The cr
Page 252 and 253: Table 19.1 Site concreting and rein
Page 256 and 257: Site concreting and reinforcement 2
Page 266 and 267: eason, the contractor has to take s
Page 272 and 273: Acceptance of tender 76 ACE (Assn.
Page 274 and 275: Design options 24 et seq. Design an
Page 276 and 277: One stop shop 15 Opening tenders 71
Page 278 and 279: Time schedule of key dates 168 Tran
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Plate 12a. On any job not properly
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Plate 14a. The typical fluidity of
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Plate 16a. If reinforcement is not
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