Christchurch, New Zealand
Christchurch, New Zealand

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Hughes C.G.C.,Opus International Consultants Ltd. | Read K.J.,Opus International Consultants Ltd. | Watson M.,ScanTec Ltd.
Proceedings of the 5th International Conference on Geotechnical and Geophysical Site Characterisation, ISC 2016 | Year: 2016

In this paper we describe two case studies where a combination of geophysics and 'conventional' geotechnical techniques was used to characterise the sites for risk associated with voids in near surface soils that could potentially collapse. One is a former mine site where collapse of mineshaft back fill has occurred. Before intrusive investigations were carried out desk studies highlighted the possibility of other shafts on the site and voids below demolition rubble. In order to assess the potential risk from these an initial Ground Pene-trating Radar (GPR) survey was carried out and possible voids identified. This enabled targeted ground inves-tigation and safe siting of plant and workers. The second case is an electricity substation where 'tomos', (shal-low and potentially large voids created by piping erosion in pumice rich sands) were suspected. To improve the likelihood of striking a tomo in a borehole, reduce the risk of provoking an unexpected collapse and of striking buried services, a GPR survey was first carried out. In both cases further intrusive investigation is necessary to locate voids but this has potential for collapse, threatening the health and safety of site users and those carrying out investigation(s). By firstly characterising these sites through desk studies and GPR, we could carry out fu-ture works more safely and optimise our intrusive investigation. © 2016 Australian Geomechanics Society.

Easton M.R.,Opus International Consultants Ltd. | Eastwood P.R.,Opus International Consultants UK Ltd.
Geotechnical Engineering for Infrastructure and Development - Proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2015 | Year: 2015

During 2011, the city of Christchurch in the South Island of New Zealand became "earthquake central" with large numbers of earthquakes and aftershocks affecting a 350,000 population. This paper investigates the impacts of the earthquakes on rockfall on to residential areas, and Lyttelton tunnel, the lifeline structure connecting Christchurch to its only deep water port. Structures that were designed to survive direct seismic loadings were also subjected to the indirect impacts of "boulder rolling". Boulders in excess of 10 Tonnes were mobilised by very high ground accelerations, which subsequently rolled down the slopes causing significant devastation and injury. The challenge was to provide immediate, rapidly deployable solutions to protect to the most sensitive areas and maintain operational capacity, then assess the long-term risk, communicate that risk and, where appropriate, provide mitigation measures. Rockfall risk assessment, trajectory analysis and critical asset identification was adopted to enable targeted blasting/scaling, source stabilisation and installation of rockfall barriers making for functional yet innovative and practical solutions. © The authors and ICE Publishing: All rights reserved, 2015.

Mandeno W.,Opus International Consultants Ltd
Annual Conference of the Australasian Corrosion Association 2012 | Year: 2012

Thermally sprayed metal (TSM) includes proven long term protective coating systems for steelwork in a marine environment such as thermal sprayed zinc (TSZ) and thermal sprayed aluminium (TSA); however specifiers have been slow to adopt these in Australia. This paper reviews the technology then looks at several projects in New Zealand and overseas, some where a premature failure has occurred, and discusses these and the lessons that should be learned. It concludes with recommendations as to how coating specifications could be improved so that TSM's potential long life performance can be achieved. Copyright © (2012) by the Australasian Corrosion Association.

Gerbrandt R.C.,Opus International Consultants Ltd.
Bulletin of the New Zealand Society for Earthquake Engineering | Year: 2014

The Tauroa residential subdivision is situated in the hills of southern Havelock North in Hawke's Bay, New Zealand. The development proposal includes removal of a moderately deep (<10 m) landslide and its replacement with an engineered fill slope. A simplified "screening analysis" method was utilised to develop reduced equivalent horizontal seismic loads for use in a pseudo-static slope stability assessment of the proposed remedial engineered fill slope. This risk-based method allows limited slope deformations to occur as a result of the design seismic event, with the magnitudes of the allowable slope deformations set in accordance with the tolerance level of the proposed development.

Lester J.R.,Opus International Consultants Ltd. | Brown A.G.,Opus International Consultants Ltd. | Ingham J.M.,University of Auckland
Engineering Failure Analysis | Year: 2013

As a result of the 4 September 2010 Darfield earthquake and the more damaging 22 February 2011 Christchurch earthquake, considerable damage occurred to a significant number of buildings in Christchurch. The damage that occurred to the Christchurch Roman Catholic Cathedral of the Blessed Sacrament (commonly known as the Christchurch Basilica) as a result of the Canterbury earthquakes is reported, and the observed failure modes are identified. A previous strengthening intervention is outlined and the estimated capacity of the building is discussed. This strengthening was completed in 2004, and addressed the worst aspects of the building's seismic vulnerability. Urgent work was undertaken post-earthquake to secure parts of the building in order to limit damage and prevent collapse of unstable parts of the building. The approach taken for this securing is outlined, and the performance of the building and the previously installed earthquake strengthening intervention is evaluated.A key consideration throughout the project was the interaction between the structural securing requirements that were driven by the requirement to limit damage and mitigate hazards, and the heritage considerations. Lessons learnt from the strengthening that was carried out, the securing work undertaken, and the approach taken in making the building "safe" are discussed. Some conclusions are drawn with respect to the effectiveness of strengthening similar building types, and the approach taken to secure the building under active seismic conditions. © 2013 Elsevier Ltd.

McCarten P.S.,Opus International Consultants Ltd
Bridge Maintenance, Safety, Management and Life-Cycle Optimization - Proceedings of the 5th International Conference on Bridge Maintenance, Safety and Management | Year: 2010

Structural Health Monitoring (SHM) is a new technology in bridge and structure engineering and its integration into bridge and structures management has not yet been determined. The technology involves tracking of any aspect of a bridges health by using reliably measured data and analytical simulations in conjunction with heuristic experience so that the current and expected future performance of the bridge for at least the most critical limit events can be described in a proactive manner. SHM has clear advantages over traditional Non Destructive Testing and Evaluation because once the monitoring is installed data flow is continuous. SHM can be visualised as measuring the 'interior' bridge condition. Bridge inspection programmes are focussed on measuring the 'exterior' bridge condition. Performance measures for bridges are being developed as the industry better understands and defines the holistic asset management inputs required to maximise the effectiveness of limited budgets and be able to present the outcomes to the wider community. Performance Indicators for bridge Essentiality, Functionality, Serviceability, Safety and Stability are being considered. Structural indicators being considered include Condition, Reliability, Risk and Work Record. Recent research has shown that risk based condition measures correlate well with bridge funding investment and it has been determined that if SHM can be integrated into the performance measures then more robust data will be available and SHM will be more readily justified. The paper considers these matters presenting options for integrating SHM data into the full range of likely performance indicators. It is recognised that SHM data will need to be collected in order for specific algorithms for the performance measures to be developed and to calibrate the performance indicators. With the development of robust performance indicators informed and transparent bridge management decision making will be achieved, and, enhanced bridge management reporting will be possible. © 2010 Taylor & Francis Group, London.

McCarten P.S.,Opus International Consultants Ltd
Bridge Maintenance, Safety, Management and Life-Cycle Optimization - Proceedings of the 5th International Conference on Bridge Maintenance, Safety and Management | Year: 2010

The New Zealand Transport Agency Bridge Manual requires composite steel girder-concrete slab bridge beams to be assessed to the NZS 3404 Steel Design requirements. To account for shear connector fracture this standard limits the shear connection capacity for partially composite beams to 50% of that required for a fully composite beam. This criterion is unduly severe often requiring load restrictions to be applied and this typically does not correlate with bridge performance. Simplified plastic analysis methods for determining the flexural strength of a steel girder-concrete slab bridge beam requires the shear connector strength to be assessed using static failure modes, being concrete bearing and shear connector shear strength, either in the gross section or fixing to the steel girder flange. Shear connector fracture is also a critical limit state through the partial composite beam transition and needs to be appropriately assessed. The paper summarises "desk top research" reviewing trends in the flexural capacity versus shear connection capacity interaction curves for composite beams with the neutral axis in either the concrete slab or the steel beam. This review has shown the reliability of the shear connector capacity can be used to model the shear connector fracture limit state through the transition, a discrete smoothed empirical transition model is rational and repeatable and for NZS 3404 Steel Design an approximate 20% increase in load carrying capacity can be achieved with this typically negating the need to load restrict bridge beams Calibration of the model is limited and further testing is suggested to confirm the appropriateness of the evaluation procedure. © 2010 Taylor & Francis Group, London.

McFarlane P.,Opus International Consultants Ltd
2013 International No-Dig Downunder | Year: 2013

The city of Christchurch has suffered a series of earthquakes which started in September 2010, and which have continued to this day. The effect on the visible built environment of the city is very obvious. Less visible, but equally serious, is the destructive effect these earthquakes have had on the unseen underground utilities. This paper discusses the rehabilitation of the brick barrel pipe network under Christchurch's Central City area which has been undertaken by the Stronger Christchurch Infrastructure Rebuild Team (SCIRT). More than 10km of brick barrel pipes, serving the stormwater and wastewater systems, have been inspected and rehabilitated using a range of trenchless techniques, adapted for optimum performance in seismic conditions. The pipes range in size from 400mm to 1,100mm diameter and consist of round, oval and egg shaped pipes. The design of the rehabilitation works commenced in early 2012. The majority of the physical rehabilitation was completed by early 2013. Completing the project in this short timeframe necessitated the use of a collaborative, integrated approach that places importance on health & safety, disruption reduction, risk mitigation and innovation. The paper discusses: · Selection of appropriate and cost-effective rehabilitation methodologies · Selection of specialist contractors · Liner design for earthquakes · Implementation of the physical works programme.

Montakhab A.,Opus International Consultants Ltd | Yusuf B.,University Putra Malaysia | Folkard A.M.,Lancaster University
Proceedings of the Institution of Civil Engineers: Water Management | Year: 2015

The distribution of aquatic vegetation within conveyance channels plays a key role in the determination of their hydraulic characteristics, especially where the vegetation is patchy, as is commonly found in nature. This paper reports the results of a laboratory flume study on flow and turbulence conditions caused by patches of the emergent rush Lepironia articulata. Acoustic Doppler velocimeter measurements were taken within and downstream of single-and multiple-patch configurations of this plant, and the effects of varying incident flow rate (0-16-0-32 m/s) and stem-scale porosity (12-4% solid volume fraction) were investigated. The results showed that flow encountering a single patch formed a turbulent wake downstream of the vegetation. Within this wake, the Reynolds stress increased downstream initially, and then decayed. When a second patch was positioned within the region of maximum Reynolds stress, the Reynolds stress decreased by between 25 and 50%. The amount of this reduction was dependent on the porosity of the vegetation and the flow rate, and was greater at lower flow rates and porosities. These changes in turbulent flow fields around patches of emergent vegetation are likely to be important in determining sediment budgets in their vicinity. ©.ICE Publishing: All rights reserved.


The invention disclosed is an adjustable support adapted to support an access hatch frame for access to a sub-surface chamber or the like. The support has a lower frame member that at least in part defines a first aperture, the first aperture having or defining a first plane, the lower frame member having at least one upper interface surface. A similar upper frame is present that defines a second aperture, a second plane, and a lower interface surface. Upper frame member also has number of height adjustable mount points. The upper and lower interface surfaces define an interface plane. Rotation of the upper frame member, relative to said lower frame member on the interface plane, adjusts the relative angle of the two.

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