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Sacramento, CA, United States

Castellanos B.A.,CH2M | Brandon T.L.,Virginia Polytechnic Institute and State University | VandenBerge D.R.,Tennessee Technological University
Landslides | Year: 2015

Fully softened shear strength is an important empirical engineering concept for slope stability analyses of cuts in stiff clays and compacted embankments constructed of high-plasticity clays. This concept has been used to explain many first-time failures for which the back calculated shear strength is below the peak strength measured in the laboratory. A comprehensive review of case histories and laboratory studies related to fully softened shear strength was used to assess the application of this concept. The case history data were also used to provide guidelines on the soil types for which fully softened shear strength is appropriate, how and when this shear strength should be used in slope stability analysis, and how the fully softened failure envelope should be characterized. This paper contains specific guidelines on when and how the fully softened shear strength concept should be used in slope stability analyses. © 2015 Springer-Verlag Berlin Heidelberg

Hunt S.W.,CH2M
ITA-AITES World Tunnel Congress 2016, WTC 2016 | Year: 2016

A paper called "Global Experience with Soft Ground and Weak Rock Tunneling under Very High Groundwater Heads" was presented at the North American Tunneling 2006 conference (Holzhäuser et.al 2006). It summarized global experience with earth pressure balance (EPB) and slurry shield tunneling on nine projects that encountered groundwater heads ranging from 6 to 11 bar. Since then, additional projects have been completed with groundwater heads ranging from 7 to 15 bar. Of these, the high pressure tunneling experience on the Lake Mead Intake No. 3 project in Nevada and on the Eurasia Tunnel (Istanbul Strait Crossing) had the greatest lengths of tunneling at face pressure over 7 bar. Experience with sustained pressurized face tunneling at groundwater heads over 7 bar and risk management observations are the focus of this paper. Copyright © (2016) by the Society for Mining, Metallurgy and Exploration. All rights reserved.

Dehdezi P.K.,CH2M | Erdem S.,Istanbul University | Blankson M.A.,University of Nottingham
Composites Part B: Engineering | Year: 2015

The use of industrial by-products in concrete would increase the sustainability of the construction industry. In this study, the potential use of scrap crumb rubber as fine aggregate in lightweight (Lytag) concrete was experimentally investigated. The effects of replacing natural sand by crumb rubber particles on the physico-mechanical, micro-structural and dynamic properties of the Lytag concrete were evaluated. When the rubber was introduced, the reduction in compressive strength of the Lytag concrete was experienced due to the less than perfect bond between the cement paste and the rubber as confirmed by the micro-structural observation. Additionally, there was flocculation of some of the crumb rubber particles and the packing of the rubber particles contributed to pockets of voids resulted in anisotropy in the concrete. The results also showed that the rubber not only meliorated the resistance of the cementitious Lytag composite to cracking from impact load but overall impact strength was also improved as the rubber particles acted as impedance to crack initiation and propagation. © 2015 Elsevier Ltd. All rights reserved.

Pontee N.I.,CH2M | Pontee N.I.,University of Southampton
Proceedings of the Institution of Civil Engineers: Maritime Engineering | Year: 2015

Large realignment sites near the mouth of an estuary have the potential to raise water levels throughout the estuary. This increase is produced by the newly created intertidal area drawing additional water into the estuary on the flood tide. Although some of this additional water enters the realignment site, a proportion also bypasses the realignment site and continues upstream, thus increasing water levels in these areas of the estuary. The modelling results described in this paper suggest that an important determinant on estuary water levels is the rate at which the realignment site fills. Schemes that fill more slowly are predicted to have less impact than those that fill more rapidly, even if high water levels within the schemes are similar. For the schemes tested in this paper, the rate at which the site flooded appeared to depend less on breach dimensions and more on the width of the site that the flood waters had to cross in order to cause full inundation. It is proposed that those options with the shortest distances result in the flood tidal waters experiencing less frictional losses. These options showed a more rapid rise in water levels within the site, and produced a correspondingly larger increase in water levels within the estuary. ©, 2015 Thomas Telford Services Ltd. All Rights reserved.

Megdal S.B.,University of Arizona | Forrest A.,CH2M
Journal - American Water Works Association | Year: 2015

Tucson (Ariz.) Water's complex jurisdictional experiences have demonstrated the importance of an open and consultative decision-making process - and demonstrated the benefits of collaboration with other utilities and jurisdictions and the value of sharing lessons learned. 2015 © American Water Works Association.

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