South East Queensland's entire rail network is capacity-capped by its reliance on passage over a single bridge at the hub of the network in Brisbane. The answer is to build a rail tunnel with passenger capacity equivalent to a 30-lane motorway, Alex Conacher reports.
DS Kieffer, Professor at Graz University of Technology, Austria, C Leelasukseree, a Lecturer at Chaing Mai University, Thailand, and GGW Mustoe, Professor at Colorado School of Mines, USA, describe recent research into the behaviour of TBM disc cutters in boulder rich ground.
The specifications used to determine the appropriate characteristics of steel fibers for reinforcement for segmental tunnel linings are described in this article. The specifications must be written to guide the direct pre-cast manufacturers who are fabricating the steel fiber reinforced concrete (SFRC) for a project. Specifications for a mix determine that it will meet compressive, flexural, and bursting strength requirements. Then, the type and quantity of steel fibers is determined based on the specified equivalent flexural strength (EFS) value. The EFS value is then confirmed through bending tests on beams. Test methods for these procedures are described. Differences in performance of different materials are illustrated and discussed. Detailed tables address various issues, including tensile strengths of various suppliers, ram bursting, ring bursting, and splitting tensile strength. The key is that engineers specify acceptance criteria in alignment with assumptions made during design.
In the last of a series of articles on abrasivity testing, B Nilsen of Norwegian University of Science and Technology (NTNU), F Dahl of SINTEF Rock and Soil Mechanics, J Holzhauser of Babendererde Ingenieure, and P Raleigh of Babendererde Engineers, introduce a new Soil Abrasion Test (SAT) that they believe has great potential for soft ground.
This article discusses the boring of tunnels in Vancouver, Canada’s Grouse Mountain that will be used for water transportation between the Capilano reservoir and the Seymour Valley. The Seymour-Capilano twin water tunnels face a number of logistical challenges in construction including the 2.3 % downhill gradient and the bedrock of granite and metavolcanic materials. The project will support a massive water treatment program. A 3.8 meter diameter tunnel boring machine (TBM) cutterhead was used with 19 inch cutters, supplemented with a rail-bound mucking system with trains of 5.4 cubed meters. Progress averaged at 28 meters per day with round the clock shifts. One positive note given is that excavators never encountered a fault line, although one was anticipated.
This article describes a project at Washington Dulles International Airport in Virginia involving a complete overhaul of ground transportation systems for passengers. The main thrust is an Automated People Mover (APM), which is being built in a number of stages. Additional projects include a major NATM utility tunnel, which is the most advanced tunneling project. Custom built timber framing and in-situ concrete casting of a lining in a sharp L junction are some salient aspects. The East APM corridor contract, worth $235 million, achieved a major milestone when its two TBMs arrived on site in late 2005. The west APM corridor is similar, though on a smaller scale. All the projects are being carried out side by side with ongoing operations, requiring construction to adjust to avoid interfering with terminal activities.
This article describes the impetus behind the Canadian $600 million design-build contract for the 10.4 kilometer long Niagara Tunnel in Canada that will deliver water to the newly upgraded Sir Adam Beck Hydroelectric Power complex operated by Ontario Power Generation (OPG). Some of the interesting features of the contracted as listed include the use of an open-gripper tunnel boring machine (TBM) rather than a shielded device, instead of bringing in cast-in-place lining for the last layer of lining casting the segments in situ, and, lastly, building the TBM to be used on site rather than at a commissioned shop. Site builds for TBM are uncommon and, despite a faster delivery time of the specified machine, they have a number of associated complications. Finally, the most complicated logistical consideration was the contractor’s decision to cast in situ lining as the TBM advanced rather than upon completion of the entire tunnel.
Max John, consulting engineer to the ILF Group, and Bruno Mattle, of ILF Consulting Engineers, describe how shotcrete lining, vital as support in low overburden tunnels, is modelled in numerical analysis
Two of the UK's premier universities, Oxford and Cambridge, are collaborating on a major tunnelling research programme into the effective use of soil conditioning and lubricating agents. Robert Mair, Andrew Merritt and Xavier Borghi of Cambridge University's Engineering Department, and Hiroshi Yamazaki and Toshifumi Minami of Nishimatsu Construction Co. Ltd, describe the research underway.
Unexpected drill bit wear during drill and blast tunnelling can prove surprisingly costly. In this article Dipl. Geol. Ralf J Plinninger, Prof. Dr. Georg Spaun and Dr. Kurosch Thuro present their latest methodology for predicting and classifying tool wear.
Grouting in tunnel excavation has been used to prevent major water inflows and reduce the amount of water that must be pumped out of the tunnel system. Pre-grouting can improve the quality of the rock mass for easier excavation because it fills joints and voids, strengthens parts of the rock mass, and reduces water flow. Recent developments in grouting materials and grouting technology in Norway are improving the possibility of rock improvements through grouting. (See also Part 2, Tunnels and Tunnelling International, V 34, N 1, January 2001, TRIS 00824473.)
