Business profile
ground beneath the railway. This design was offered to the market for the design and build price during tendering. HOCHTIEF saw this as an opportunity to reduce the risk of pushing two boxes below the railway and opted for a single box solution. This significantly reduced disturbance to the ground supporting the operational railway above and was more cost-effective and less programme intensive.
The Cliffsend underpass is the longest
method of construction was adopted. Excavation was carried out under water inside a circular cofferdam formed by a 53m diameter 28m deep reinforced concrete diaphragm wall. At the same time the RC basement was constructed at ground level next to but outside the diaphragm wall - both built inside a dry dock wall. Once excavation was complete and the RC basement constructed the dry dock was flooded, allowing the RC structure to be floated over its permanent position within the diaphragm wall. This totally eliminated the need for long-term ground water pumping required by conventional in situ methods which would have entailed the disposal of vast quantities of water into sensitive receptors. ‘The on-land floating of the 8000 tonne concrete basement using a custom-made sheet
piled dry dock demonstrates the ingenuity and innovative thinking that is synonymous with HOCHTIEF. An exceptional feat of civil engineering.’ Keith McGurk, regional director, Veolia Environmental Services
Finally a recent scheme, the East Kent Access phase 2 project (2009-2012), delivered a 126m underpass (known as Cliffsend underpass) below an operational railway. The Cliffsend underpass formed part of the overall scope which also included a bridge over rail and 8km of dual carriageway. The underpass original reference design
indicated two large side-by-side precast concrete boxes, each large enough to accommodate two lanes of traffic, assumed to be thrust into position through the
jacked structure in the world to date at 126m long, 6m high and 25m wide. Construction methodology involved boring a pair of 3.5m temporary tunnels below the railway along the lines of the underpass side walls. Within and through the bases of these tunnels, rows of reinforced mini-piles provided support to side-walls and roof. The reinforced concrete deck units were constructed to the west of the underpass in six sections using a single-shutter formwork system with the deck supported on scaffold. Using hydraulic jacks the deck units were jacked under the railway using a jacking force of 350,000kN on slide tracks. At the same time as the jacking operation, the ground immediately in front of, and beneath, the roof sections was excavated and removed in a mining operation. The 126m structure was positioned
beneath the operational railway in eight weeks, without disruption of a single train. The project was recently recognised at
the 2013 ICE Awards with an Innovation award for the methods employed at Cliffsend underpass. ‘The construction techniques employed at the Cliffsend underpass are world class and demonstrate what HOCHTIEF is known for globally, innovative solutions to complex construction problems.’
Geoff Cripps, major projects manager - Kent County Council
Wider benefits for clients
HOCHTIEF offers a wealth of experience, bringing the knowledge and skill of its professional engineering staff. Seeking solutions to complicated construction problems, it offers benefits to the client in terms of efficiencies in design programming and end-cost.
The company’s values are aligned to its clients’ and it operates a policy of equality, inclusion and diversity within its organisation. It is committed to an open and honest contracting approach, delivering value engineering through innovation and continuous improvement. Through a positive attitude to stakeholder and third party interests it has managed the most complex of projects. It delivers schemes to clients’ exacting specifications engaging with all interested parties to make it happen. •
Contact: David Orchard
david.orchard@hochtief.co.uk Visit:
www.hochtief.com
November 2013 Page 123
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140