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In the present study, the problem of railway stiffness transitions, for example, railway tracks near bridge abutments or tunnels, was investigated numerically in terms of track deterioration and passenger comfort utilising two types of analysis. The first analysis employed a train–transition curve model which simulates the response of the train to deflection changes in the vicinity of the transition zone. The second analysis used a three-dimensional (3D) finite-element representation of the railway track interacting with a passing train. The effects of train speed, track stiffness changes and the presence of a track fault were addressed. The findings of this research are compared against available studies in the literature and recommendations are given towards an appropriate engineering design of transition zones.

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Global climate change, related to the greenhouse gases emission, impacts hydroelectric power generation mainly due to the increase in air temperature and changes in the precipitation patterns. As a consequence, it affects basin evapotranspiration process, runoff, sediment transport as well as evaporation of reservoirs. This study analysed the current and future Brazilian context of hydroelectric reservoirs and investigated the potential impacts of climate change on hydropower generation and possible mitigation adjustments, giving relevant examples from around the world. Moreover, it is key to consider other factors that influence the availability of water resources such as: (a) upstream development of reservoirs, mainly the development of agricultural systems, which can contribute to increased water demand; (b) changes in land use, which can have an impact on soil degradation and sediment transport. Hydroelectric dams are a possible alternative to mitigate the impacts of climate change considering that those impacts could generate the need of adaptive actions. The assessment of climate change impacts' projections anticipates possible future scenarios and can assist in strategic planning together with the definition of adaptive operational policies.

Recent research has highlighted the effect of the individual contributions of the crib, shoulder, and base resistance to the lateral behaviour of a typical railway sleeper under loading. The contribution of the shoulder ballast has been seen to provide around 30 per cent of the lateral resistance for an unloaded sleeper. The addition of extra ballast in the shoulder area provides a very limited increase in lateral sleeper resistance. It is common in areas of high lateral loading, such as switch and crossings, to provide sleeper end plates to improve the passive resistance of the track. Sleeper end plates have, however, many disadvantages, not least is the need to disturb the ballast in order to facilitate their installation. The application of polyurethane reinforcement of the ballast shoulder to rapidly form an in situ GeoComposite shoulder beam (geobeam) has many advantages over end plates, including the ability of the lateral beam to be installed directly after the track geometry has been corrected; the lateral track geometry can then be 'captured' at installation. The beam can also be formed while the trains are still running. In this article the application of lateral GeoComposite side beams to improve the passive resistance of the shoulders is illustrated through analytical and numerical analysis. The application of the technique to actual problem sites is also presented and the performance of the technique at the Harford bridge transition site discussed.

If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The influence of flood conditions upon traditional cob construction is little understood. This paper aims to investigate the ability of cob materials to resist flood situations and documents basic failure mechanisms. This work also seeks to investigate the wettability characteristics of cob materials utilising environmental scanning electron microscopy. Design/methodology/approach -This paper takes the form of a literature review and case study underpinning laboratory experiments. Findings -Cob walls that are suitably compacted, straw reinforced and are composed and manufactured of the correct materials appear to have the ability to resist total failure when subjected to initial flood conditions, however, the duration to which these structures will remain intact has still to be ascertained, and testing is ongoing. A correlation appears to exist between the rate of cob material's compaction and the duration to which the structural integrity of the walls was retained when the samples were submerged in water. In addition, the use of straw reinforcing increased the duration to which the wall could be submerged before failure. Un-reinforced cob walls that were submerged in simulated floodwaters, exhibited an undercutting pattern of deterioration prior to failure. The materials for cob construction exhibited both hydrophobic and hydrophilic characteristics. This would have an influence on the material's ability to saturate and dehydrate, and also have an impact on moisture transfer mechanisms. Unsaturated cob wall/samples developed surface tension between hydrophilic surfaces and this is believed by the authors to increase inter-particle bond strength within the material by the suction effect. Originality/value -This paper is believed to be the first preliminary investigation into the effect of flooding on cob structures. Additionally, it utilises environmental scanning electron microscopy to reveal information about the surface characteristics of the materials and uses wettability studies to assess the hydrophilic and hydrophobic nature of the aforementioned.

Citation for published item:vouren oD F hF xF nd qllipoliD hF nd ollD hF qF nd eugrdeD gF iF nd ivnsD pF hF nd wederoD qF wF @PHHVA 9glirtions of high sution tensiometerF9D q¡ eotehniqueFD SV @VAF ppF TSWETTVF Further information on publisher's website: httpXGGdxFdoiForgGIHFITVHGgeotFPHHVFSVFVFTSW Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. , et al. (2008). Géotechnique 58, No. 8, 659-668 [doi: 10.1680/geot.2008 659Calibrations of a high-suction tensiometerHigh-suction tensiometers are able to measure suctions up to 2 MPa. Direct calibration at such high suctions requires the imposition of negative water pressures, which are difficult to achieve using facilities commonly available in soil mechanics laboratories. For this reason, tensiometers are usually calibrated in the positive pressure range, and such calibration is subsequently extrapolated to negative pressures. This paper examines different experimental techniques to assess the accuracy of such extrapolation. Any error in the calibration process would be directly reflected in the measured values of suction, and might be particularly significant (in relative terms) for the measurement of low suctions. In addition, the results of this study show that calibration in the positive range is affected both by the physical configuration of the tensiometer during calibration and by aspects of its design. The paper concludes that linear extrapolation of the calibration from the positive to the negative range is sufficiently accurate provided that calibration is done under conditions that closely match the conditions in which the tensiometer will be used. Owing to structural differences between tensiometers, and also to suctioninduced 'calibration hysteresis', at least one check on the accuracy of the extrapolated calibration equation over a range of negative pressure should be performed, even if at low values of suction.

This paper presents the measured results of full-scale testing of railway track under laboratory conditions to examine the effect on the track stiffness when the ballast is reinforced using a urethane cross-linked polymer (polyurethane). The tests are performed in the GRAFT I (Geopavement and Railways Accelerated Fatigue Testing) facility and show that the track stiffness can be significantly enhanced by application of the polymer. The track stiffness is measured at various stages during cyclic loading and compared to the formation stiffness, which is determined prior to testing using plate load tests. The results indicate that the track stiffness increased by approximately 40 to 50% based on the measured results and from the previously published GRAFT I settlement model. The track stiffness was monitored during loading for a maximum of 500,000 load cycles. The paper concludes by presenting and commenting on, the application of the technique to a real site where the Falling Weight Deflectometer was used before and after polymer treatment to determine the dynamic sleeper support stiffness. The very challenging site conditions are highlighted, in particular the water logged nature of the site, and comment made on the effect of the water on polymer installation. The results of the FWD measurements indicate that a good increase in overall track stiffness was measured. These results are consistent with the laboratory tests which are performed on a different soil and use a different measurement technique and hence confirm that regardless of the soil and measurement system track stiffness increases are observed using this technique.