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Aldiss D.T.,British Geological Survey | Black M.G.,Crossrail Ltd | Entwisle D.C.,British Geological Survey | Page D.P.,OtB Engineering UK LLP | Terrington R.L.,British Geological Survey
Quarterly Journal of Engineering Geology and Hydrogeology | Year: 2012

In the design of major construction works, the better the ground conditions are known, the more control there is on the assessment of risks for construction, contract and personnel, and ultimately on final costs. Understanding of the ground conditions is usually expressed as a conceptual ground model that is informed by the results of desk study and of dedicated ground investigation. Using the GSI3D software, a 3D geological model (a model composed of attributed solid volumes, rather than of surfaces) can be constructed that exactly honours geologists' interpretations of the data. The data are used in their true 3D position. The 3D model of faulted Lambeth Group (Palaeogene) strata in the area of the proposed new Crossrail Farringdon underground station, in central London, has several types of benefit. These include allowing optimum use of available ground investigation data, including third party data, with confidence. The model provides an understanding of the local geological structure that had not been possible using other commonly used methods: in particular, it shows the likely distribution of numerous water-bearing coarse deposits and their faulted offsets, which has potentially significant effects on groundwater control. The model can help to focus ground investigation, constrain design and control risk. © 2012 Geological Society of London.


Mortimore R.,University of Brighton | Newman T.G.,Thames Water Utilities | Royse K.,British Geological Survey | Scholes H.,Geotechnical Consulting Group GCG | Lawrence U.,Crossrail Ltd
Quarterly Journal of Engineering Geology and Hydrogeology | Year: 2011

The geology of the Chalk beneath east London and the Thames Gateway is reviewed and key features affecting engineering geology are summarized. In particular, the variable stratigraphy preserved beneath the sub-Palaeogene erosion surface, the evidence for syndepositional tectonics in the Chalk, and the recognition of tectonic fractures and strata-bound fracture systems are emphasized. The contrasting physical properties of chalk and flint are discussed and the depth of weathering in the subcrop and outcrop are compared and contrasted. The information gained from separate ground investigations is combined to suggest that there are regions in east London where better quality chalk and less permeable ground are present between regions of poorer quality chalk with higher permeability, closely related to zones of faulting. © 2011 The Geological Society of London.


Wan M.S.P.,Crossrail Ltd | Wan M.S.P.,Imperial College London | Standing J.R.,Imperial College London
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2014

Subsurface instrumentation was installed at a field monitoring site in Hyde Park and bordering Bayswater Road for measuring the ground responses to Crossrail tunnelling near Lancaster Gate. Prior to tunnel construction, porewater pressures were measured, both in the ‘greenfield’ ground and the ground in the vicinity of existing London Underground running tunnels, by three multi-level vibrating-wire piezometer boreholes fully backfilled with cement-bentonite grout. The pore-water pressures in the ‘greenfield’ ground were at the same time measured by conventional standpipe piezometers and pushed-in spade cells with built-in vibrating-wire piezometers. This paper investigates the performance of the multi-level vibrating-wire piezometers by comparing their post-installation and steady-state pore-water pressure measurements with those from the other piezometer types. Generally they performed well, providing an efficient means of determining pore-water pressures at several depths within one borehole. One of the ‘greenfield’ multi-level vibrating-wire piezometers indicated underdrainage within the London Clay while the other was influenced by inter-connectivity between individual piezometers within the borehole and also the presence of a claystone horizon. One borehole close to the existing tunnel indicated drainage of groundwater into it; this effect is compared with predictions made using a simplistic finite-difference model. © 2014, Thomas Telford Services Ltd. All rights reserved.


Smith P.,Geotechnical Consulting Group | Lawrence U.,Crossrail Ltd | Terry S.,Crossrail Ltd | Cooke S.,Alpha Associates
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2013

Site investigation works undertaken as part of the Crossrail cross-London railway project over the last 10 years have involved extensive intrusive works into the ground in areas of London which were known to have been heavily bombed during the Second World War. This bombing created a legacy of unexploded ordnance risk to such works. This paper explains how a procedure was developed to enable the risk to the ground investigation works to be assessed and for appropriate and effective measures to be identified where necessary to mitigate this risk. It is shown that the developed procedure is consistent with that now recommended by the Ciria guide on unexploded ordnance, and provides a practical illustration of how an appropriate risk assessment procedure can avoid extensive and unnecessary mitigation works on site, while ensuring that when mitigation measures are undertaken, it is where and when they are truly needed to enable work to progress safely.


Dulake C.,Crossrail Ltd
Geomechanik und Tunnelbau | Year: 2011

Crossrail is a new railway currently being constructed in London and is the largest construction project in Europe. Linking existing surface railways to the east and west of the capital via 21 km of new twin bore tunnels it will run 118 km from end to end. This paper briefly summarises the benefits of the scheme and its sustainability strategy and goes on to describe the design of the sprayed concrete and bored tunnels, management and mitigation of ground movements. It finishes by outlining the contractual framework for the procurement of the main construction contracts. © 2011 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co.


Wan M.S.P.,Crossrail Ltd | Wan M.S.P.,Imperial College London | Standing J.R.,Imperial College London
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2014

Imperial College in London, UK, as part of an Engineering and Physical Sciences Research Council (EPSRC) funded research project and in collaboration with Crossrail urban railway project, is performing field monitoring research to investigate how tunnelling affects existing tunnels. Comprehensive instrumentation was installed in Hyde Park and bordering Bayswater Road, beneath which the new Crossrail tunnels were constructed in London Clay below the existing London Underground Central Line tunnels. Surface and subsurface instruments were installed around the Crossrail tunnel alignments to monitor the ground response to the tunnel construction. Monitoring systems of sufficient resolution and accuracy were adopted to achieve high-quality data for assessing the tunnelling-induced ground response and mechanisms of movement from earth-pressure-balance machine tunnelling. The installation of surface and subsurface instrumentation took place in the summer of 2011. This paper describes and discusses the installation of rod extensometers, in-place inclinometers and multi-level vibrating-wire borehole piezometers. Selection of the appropriate cement-bentonite grout mixes for backfilling these borehole instruments is discussed, as this is critical for representative measurements of ground response. Some practical challenges arising during the installation process and how they were overcome are also described. Confidence in the instrument performance is demonstrated using example monitoring results from the piezometer and extensometer installations. © ICE Publishing: All rights reserved.


Yeow H.-C.,Flint and Neill Ltd | Nicholson D.,Arup | Man C.-L.,Atkins | Ringer A.,Kier Engineering | And 2 more authors.
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2014

Excavation of the western ticket hall box at Tottenham Court Road station represented a critical path activity of the Crossrail railway project in London, UK. Base slab construction and preparatory sprayed concrete lining works needed to be completed before the arrival of the two tunnel boring machines. A full observational method (OM) design was implemented to eliminate the lowest level of temporary propping, resulting in a 13 m prop-free excavation at the bottom of the 30 m deep diaphragm wall station box. This paper describes the design and successful implementation of the OM, which eliminated the need to fabricate, install and remove the fifth level of temporary propping. It covers the comprehensive review of the original design input parameters, back analysis of the most probable geotechnical design parameters and comparison of wall deflection and forces in the temporary props from early stages of the construction works. The robust strategy formulated as part of the observational method design to control the subsequent excavation is described: this included trigger criteria, a review process and predetermined contingency measures to ensure safe execution of the excavation works. A genuinely collaborative effort between client, permanent and temporary works designers, independent design checker and the contractor is elaborated. Cost and programme savings achieved by implementation of the observational method approach are outlined. © ICE Publishing: All rights reserved.


Douglas A.,Mott MacDonald Ltd. | Smith M.,Bam Nutall Kier joint venture | Hunter J.,Crossrail Ltd
Proceedings of the Institution of Civil Engineers: Civil Engineering | Year: 2015

The Moorgate shaft at Crossrail Liverpool Street station is one of the deepest in London, UK. Construction of the base slab to the 42 m deep shaft required close collaboration between the client, designer, contractor and suppliers to give assurance that the slab was watertight. Dense reinforcement was detailed to ensure ease of fixing within the tight confines of the shaft and allow for the tolerance on the diaphragm walls. The concrete design was developed to ensure that it met the requirements for placing and structural strength while achieving good control on the temperature developed. The concrete mix was trialled for temperature development and initial set to allow relaxation of the original specification. The pour plan was developed with the co-operation of all the site teams to ensure appropriate contingency measures were in place. Temperature monitoring was carried out to ensure that mitigation measures could be applied to control placed concrete temperature against predetermined trigger levels. © The authors and the Institution of Civil Engineers. 2015.


Morgan T.,Cross rail Ltd.
Proceedings of Institution of Civil Engineers: Management, Procurement and Law | Year: 2011

With a positive outcome from the UK government's 2010 comprehensive spending review, the Cross rail cross-London railway project has started awarding its main construction contracts. The author explains how risk management has already benefited the project and why its adoption by the supply chain is critical.


Hinde P.,Crossrail Ltd.
IET Seminar Digest | Year: 2010

Summary form only given. A career that has been spent largely in rail operations and maintenance, and in project managing the introduction of new trains, gives a slightly different perspective to the technical themes that have been covered during this course.

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