The Experts below are selected from a list of 3660 Experts worldwide ranked by ideXlab platform

Michael W Pierce - One of the best experts on this subject based on the ideXlab platform.

  • enhanced predictions for peak outflow from breached Embankment Dams
    Journal of Hydrologic Engineering, 2011
    Co-Authors: Christopher I Thornton, Michael W Pierce
    Abstract:

    A study was conducted to enhance the historic regression relations that predict the peak discharge from breached Embankment Dams. Forty-four dam breach case studies were collected and added to an existing database resulting in a composite database of 87 case studies. The composite database was evaluated and a statistical analysis performed using regression techniques. Peak outflow ( Qp ) prediction expressions from breached Embankment Dams were developed as a function of the height of the dam (H) , the volume of water behind the dam (V) , the Embankment length (L) , the average Embankment width ( Wave ) , and a combination of these variables. The multivariate regression analysis indicated that a series of expressions may be formulated relating peak outflow as a function of H⋅V⋅L and H⋅V⋅ Wave . The newly developed expressions derived from the expanded database appear to reduce the conservatism in predicting the peak discharge from a breached Embankment, reduce the prediction error, and reduce the uncertai...

  • predicting peak outflow from breached Embankment Dams
    Journal of Hydrologic Engineering, 2010
    Co-Authors: Christopher I Thornton, Michael W Pierce
    Abstract:

    From 1977 to 1995, a series of regression relations were developed to predict the peak discharge from breached Embankment Dams. In 2008, a study was conducted to review previous investigations, expand the working database of dam failures, and evaluate the appropriateness of the existing relationships. Forty-four case studies were collected and added to the existing database, resulting in a composite database of 87 case studies. The composite database was evaluated and a statistical analysis was performed using linear, curvilinear, and multiple-regression techniques. Enhanced simple- and multiple-regression expressions were developed to predict peak-breach discharge as a function of the height and/or volume of water behind the dam. A comparison of selected historical and newly derived expressions indicates that three previously developed relations remain valid for conservative peak outflow predictions. Newly developed expressions relating peak outflow as a function of the height (H) and/or volume (V) of wa...

Christopher I Thornton - One of the best experts on this subject based on the ideXlab platform.

  • enhanced predictions for peak outflow from breached Embankment Dams
    Journal of Hydrologic Engineering, 2011
    Co-Authors: Christopher I Thornton, Michael W Pierce
    Abstract:

    A study was conducted to enhance the historic regression relations that predict the peak discharge from breached Embankment Dams. Forty-four dam breach case studies were collected and added to an existing database resulting in a composite database of 87 case studies. The composite database was evaluated and a statistical analysis performed using regression techniques. Peak outflow ( Qp ) prediction expressions from breached Embankment Dams were developed as a function of the height of the dam (H) , the volume of water behind the dam (V) , the Embankment length (L) , the average Embankment width ( Wave ) , and a combination of these variables. The multivariate regression analysis indicated that a series of expressions may be formulated relating peak outflow as a function of H⋅V⋅L and H⋅V⋅ Wave . The newly developed expressions derived from the expanded database appear to reduce the conservatism in predicting the peak discharge from a breached Embankment, reduce the prediction error, and reduce the uncertai...

  • predicting peak outflow from breached Embankment Dams
    Journal of Hydrologic Engineering, 2010
    Co-Authors: Christopher I Thornton, Michael W Pierce
    Abstract:

    From 1977 to 1995, a series of regression relations were developed to predict the peak discharge from breached Embankment Dams. In 2008, a study was conducted to review previous investigations, expand the working database of dam failures, and evaluate the appropriateness of the existing relationships. Forty-four case studies were collected and added to the existing database, resulting in a composite database of 87 case studies. The composite database was evaluated and a statistical analysis was performed using linear, curvilinear, and multiple-regression techniques. Enhanced simple- and multiple-regression expressions were developed to predict peak-breach discharge as a function of the height and/or volume of water behind the dam. A comparison of selected historical and newly derived expressions indicates that three previously developed relations remain valid for conservative peak outflow predictions. Newly developed expressions relating peak outflow as a function of the height (H) and/or volume (V) of wa...

G L Jiang - One of the best experts on this subject based on the ideXlab platform.

  • safety inspection strategy for earth Embankment Dams using fully distributed sensing
    Procedia Engineering, 2011
    Co-Authors: Y B Leng, Y Zhou, G L Jiang
    Abstract:

    Abstract Both the changes in temperature and strain during the process are used to reveal serious seepages and settlements occurring inside the Embankment dam. A method for seepage and settlement monitoring in earth Embankment Dams using fully distributed sensing along optical fibres is proposed. The proposed monitoring system also offers the owner the strategy of the inspection and maintenance in earth Embankment Dams. The database in the control and maintenance center is described. In this paper, as an example, a model filled with the soil from Yellow River is built and bare optical fibers are embedded under different soil layers near the seepage path. The configuration of optical sensing cable in series of Embankment Dams is developed. The simulated seepage flows under various flow rates are monitored using the optical fibers and measured by a DiTeSt –STA202 distributed temperature and strain analyzer. A partial settlement within the Embankment dam model is observed. The continuously decreasing temperature curve shows an abrupt dramatic increasing rate, which shows that the change is not caused by the temperature of the seepage water but the strain. The information from the monitoring center provides important reference for the expert decision-making system to ensure the safety of the Embankment dam long running.

  • seepage and settlement monitoring for earth Embankment Dams using fully distributed sensing along optical fibers
    2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications, 2008
    Co-Authors: Y Zhou, Luc Thevenaz, G L Jiang
    Abstract:

    A method for seepage and settlement monitoring in earth Embankment Dams using fully distributed sensing along optical fibres is proposed. A model is developed for simulating and monitoring seepage and settlement systems. This model relates the strains and the temperature changes to the fiber Brillouin gain spectrum in the Embankment dam embedding the optical fiber sensors. The model consists of two parts. Submodel 1 addresses the simulation of seepage inside the Embankment dam. Submodel 2 relates the measurement of the fiber Brillouin gain spectrum to the changes in temperature and strain inside the Embankment dam. Both the changes in temperature and strain during the process are used to reveal serious seepages and settlements occurring inside the Embankment dam. The continuously decreasing temperature curve shows an abrupt dramatic increasing rate, which shows that the change is not caused by the temperature of the seepage water but the strain. In this paper, as an example, a model filled with the soil from Yellow River is built and bare optical fibers are embedded under different soil layers near the seepage path. The simulated seepage flows under various flow rates are monitored using the optical fibers and measured by a DiTeSt -STA202 distributed temperature and strain analyzer. A partial settlement within the Embankment dam model is observed.

Robin Fell - One of the best experts on this subject based on the ideXlab platform.

  • transverse cracking in Embankment Dams resulting from cross valley differential settlements
    European Journal of Environmental and Civil Engineering, 2019
    Co-Authors: Ke He, Robin Fell, Chongmin Song
    Abstract:

    This article investigates transverse cracking in Embankment Dams resulting from cross-valley differential settlements during and post-construction, in which concentrated leak erosion may initiate. ...

  • experimental investigation of global backward erosion and suffusion of soils in Embankment Dams
    Canadian Geotechnical Journal, 2019
    Co-Authors: Kurt Douglas, Robin Fell, William L Peirson, Hamish Studholme
    Abstract:

    Many Embankment Dams constructed with a core of nonplastic or very low plasticity silt–sand–gravel (typically of glacial, fluvioglacial or alluvial origin) have experienced internal erosion. This h...

  • laboratory tests on the rate of piping erosion of soils in Embankment Dams
    Geotechnical Testing Journal, 2004
    Co-Authors: Robin Fell
    Abstract:

    The Slot Erosion Test and the Hole Erosion Test have been developed as fast and simple tests for studying the erosion characteristics of soil in cracks in Embankment Dams. The erosion characteristics are described by the Erosion Rate Index, which measures the increase of erosion rate with respect to an increase in the hydraulic shear stress; and the Initial Shear Stress, which represents the minimum hydraulic shear stress when erosion starts. Knowledge of these erosion characteristics aids in the prediction of the likelihood of Embankment dam failure due to piping erosion in a risk assessment process. Values of the Erosion Rate Index span from 0 to 6, indicating that the changes in erosion rates in response to changes in hydraulic shear stress can differ by up to 106 times across different soils. The Erosion Rate Index is apparently influenced by the soil fines and clay-sized content, plasticity, dispersivity, water content, dry density, degree of saturation, clay mineralogy, and possibly the presence of cementing materials such as iron oxides. Coarse-grained, noncohesive soils, in general, erode more rapidly and have lower Initial Shear Stresses than fine-grained soils.

  • investigation of rate of erosion of soils in Embankment Dams
    Journal of Geotechnical and Geoenvironmental Engineering, 2004
    Co-Authors: Robin Fell
    Abstract:

    The slot erosion test and the hole erosion test have been developed to study the erosion characteristics of soil in cracks in Embankment Dams. The erosion characteristics are described by the erosion rate index, which measures the rate of erosion, and the critical shear stress, which represents the minimum shear stress when erosion starts. Values of the erosion rate index span from 0 to 6, indicating that soils can differ in their rates of erosion by up to 10 6 times. The rate of erosion is shown to be dependent on the soil fines and clay sized content, plasticity, and dispersivity; compaction water content, density and degree of saturation; and clay mineralogy, and possibly the presence of cementing materials such as iron oxides. Coarse-grained, noncohesive soils, in general, erode more rapidly and have lower critical shear stresses than fine-grained soils. Knowledge of the erosion characteristics of the soil in the core of an Embankment dam aids in the assessment of the likelihood of dam failure due to piping erosion.

  • Time for Development of Internal Erosion and Piping in Embankment Dams
    Journal of Geotechnical and Geoenvironmental Engineering, 2003
    Co-Authors: Robin Fell, Chi Fai Wan, John Cyganiewicz, Mark Foster
    Abstract:

    A method is presented for the approximate estimation of the time for progression of internal erosion and piping, and development of a breach leading to failure in Embankment Dams and their foundations. The method accounts for the nature of the soils in the dam core, the foundation, and the materials in the downstream zone of the dam. Guidance is also provided on the detectability of internal erosion and piping, taking account of the mechanism of initiation, continuation, and progression to form a breach, for internal erosion and piping in the Embankment, the foundation and from the Embankment to foundation. It is shown that in many Dams which have poor internal erosion and seepage control and are constructed mainly of earthfill, the time for potential development of piping is short, and for these Dams continuous monitoring of seepage or surveillance would be needed to detect the piping in time to give warning of possible failure, and to give time to attempt intervention to prevent the failure.

Kaare Hoeg - One of the best experts on this subject based on the ideXlab platform.

  • cyclic behavior of asphalt concrete used as impervious core in Embankment Dams
    Journal of Geotechnical and Geoenvironmental Engineering, 2011
    Co-Authors: Weibiao Wang, Kaare Hoeg
    Abstract:

    Asphalt concrete is used as a water barrier (interior core or upstream facing) in Embankment Dams. This paper investigates the behavior of hydraulic asphalt specimens subjected to cyclic loading in a triaxial cell. The specimens were tested at various sustained static stress states and temperatures and at maximum cyclic shear stress levels corresponding to severe earthquake shaking of the dam. The cyclic modulus versus mean sustained static stress showed an approximately linear relationship in a logarithmic diagram, and an empirical expression was developed to determine the cyclic modulus. At a mean sustained stress of 1.0 MPa, the cyclic modulus at 20°C was about 900 MPa; at 9°C, it was 1900 MPa and at 3.5°C, about 2500 MPa. The damping ratio was found to be between 0.07–0.30, depending on stress state and temperature level. The number of load cycles (up to 6000) had no significant effect on the magnitude of cyclic strain, and the cyclic loading was documented to have little effect on the postcyclic mono...

  • cyclic triaxial tests on asphalt concrete as a water barrier for Embankment Dams
    Soils and Foundations, 2008
    Co-Authors: Siamak Feizikhankandi, A.a. Mirghasemi, Abbas Ghalandarzadeh, Kaare Hoeg
    Abstract:

    ABSTRACT The seismic behavior of asphaltic concrete used in Embankment Dams subjected earthquake loads has been studied. In order to evaluate the dynamic behavior, an extensive series of monotonic and cyclic tests were carried out on triaxial specimens of asphalt concrete used in hydraulic structures. The MTS-dynamic equipment at the Norwegian Geotechnical Institute (NGI) was used for this purpose. Temperature and frequency effects on specimen behavior and on specimen degradation have been studied under the cyclic loads in both isotropic and anisotropic initial stress conditions. For investigation of the fatigue behavior, thousands of cyclic loads were imposed on some of the specimens. Moreover, to study any sign of material degradation due to the cyclic loading, the post-cyclic monotonic stress-strain curve was compared with the corresponding curve for specimens that were not first subjected to cyclic loading. Geotechnical parameters to be used in dynamic numerical analysis models are also presented.