The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform

A. Kuli - One of the best experts on this subject based on the ideXlab platform.

  • Initial Reconnaissance for a South Georgia ice core
    Journal of Glaciology, 2016
    Co-Authors: Paul Andrew Mayewski, A. Kuli, Gino Casassa, M. Arévalo, Daniel A. Dixon, Bjorn Grigholm, Michael Handley, Helene Hoffmann, Douglas S. Introne
    Abstract:

    We present the first snow/ice chemistry and ice radar results ever collected from South Georgia as part of an Initial Reconnaissance with the ultimate goal of assessing the feasibility of a South Georgia ice core to reconstruct past climate in the South Atlantic. South Georgia is well situated to capture a record of past atmospheric chemical composition over the South Atlantic and of past variability in the position and intensity of the austral westerlies. The question is how well preserved an ice core record can be recovered from a region experiencing accelerated melting? The results presented in this paper offer only a preliminary step in determining the feasibility of future deep ice coring on South Georgia. However, this Initial Reconnaissance does provide some basic information including: the chemistry of the atmosphere over South Georgia relative to other Southern Hemisphere ice coring sites; the potential for preservation of ‘annual layers’ in old ice on the island; a possible age for deep ice in the region; and an estimate of glacier health in the lower elevation regions of the island.

Alex Mathy - One of the best experts on this subject based on the ideXlab platform.

  • Combined use of geophysical methods and remote techniques for characterizing the fracture network of a potentially unstable cliff site (the 'Roche du Midi', Vercors massif, France)
    Journal of Geophysics and Engineering, 2008
    Co-Authors: Jacques Deparis, Bruno Fricout, Denis Jongmans, Thierry Villemin, Laurent Effendiantz, Alex Mathy
    Abstract:

    Stability assessment of a cliff strongly depends on the fracture pattern and the face topography. Geological observations as well as classical geodetic measurements are difficult to perform on high, nearly vertical cliffs such as the ones surrounding the town of Grenoble (French Alps). In this study we combine remote and ground imaging techniques for characterizing the geometry and the fracture pattern of potentially unstable cliff sites. A dense digital surface model (DDSM) of the rock face can now be obtained from laser scanning (Lidar) or photogrammetry. These techniques are safer and quicker than direct measurements. They offer the possibility of collecting structural data and of sampling the shape of the outcrop at a centimetric resolution. We applied these two techniques to a potentially unstable site (the 'Roche du Midi', Vercors massif) for determining the main fracture families affecting the rock mass and we obtained results similar to direct measurements performed on the nearby outcrops and on the cliff face itself. The laser scanning data suffer a bias in the illumination of the site. Geophysical experiments were also conducted on the plateau and on the cliff face in order to delineate the fracture pattern inside the rock mass. ERT (electrical resistivity tomography) and GPR (ground penetrating radar) profiles were performed on the plateau and allowed near-vertical open fractures to be located in the vicinity of the surface. The best geophysical results in terms of penetration and resolution were, however, obtained from GPR profiles conducted directly on the cliff face. Laser scanning data were combined with GPR data in order to take into account the shape of the sampled profiles. The combination of vertical and short horizontal profiles allowed the strike and dip of the discontinuities to be determined. The two main families were imaged, as well as a major continuous inward dipping reflector which was not shown during the Initial Reconnaissance. Further investigation inside the mass effectively showed the existence of this fracture. These results highlight the power of the GPR technique in characterizing the discontinuity pattern inside rock mass for improving the model in view of hazard assessment.

  • Combined use of geophysical methods and remote techniques for characterizing the fracture network of a potential unstable cliff site (the “Roche du Midi”, Vercors massif, France)
    Journal of Geophysics and Engineering, 2008
    Co-Authors: Jacques Deparis, Bruno Fricout, Denis Jongmans, Thierry Villemin, Laurent Effendiantz, Alex Mathy
    Abstract:

    Stability assessment of a cliff strongly depends on the fracture pattern and the face topography. Geological observations as well as classical geodetic measurements are difficult to perform on high nearly vertical cliffs like the ones surrounding the town of Grenoble (French Alps). In this study we combine remote and ground imaging techniques for characterizing the geometry and the fracture pattern of potential unstable cliff sites. A Dense Digital Surface Model (DDSM) of the rock face can now be obtained from laser scanning (Lidar) or photogrammetry. These techniques are safer and quicker than direct measurements. They offer the possibility to collect structural data and to sample the shape of the outcrop at a centimetric resolution. We applied these two techniques to a potential unstable site (the “Roche du Midi”, Vercors massif) for determining the main fracture families affecting the rock mass and we obtained results similar to direct measurements performed on the nearby outcrops and on the cliff face itself. The laser scanning data suffers a bias in the illumination of the site. Geophysical experiments were also conducted on the plateau and on the cliff face in order to delineate the fracture pattern inside the rock mass. ERT (Electrical Resistivity Tomography) and GPR (Ground Penetrating Radar) profiles were performed on the plateau and allowed near-vertical open fractures to be located in the vicinity of the surface. Best geophysical results in terms of penetration and resolution were however obtained from GPR profiles conducted directly on the cliff face. Laser scanning data were combined with GPR data in order to take into account the shape of the sampled profiles. The combination of vertical and short horizontal profiles allowed the strike and dip of the discontinuities to be determined. The two main families were imaged, as well as a major continuous inward dipping reflector which was not shown during the Initial Reconnaissance. Further investigation inside the mass effectively showed the existence of this fracture. These results highlight the power of the GPR technique in characterizing the discontinuity pattern inside rock mass for improving the model in view of hazard assessment.

Jacques Deparis - One of the best experts on this subject based on the ideXlab platform.

  • Combined use of geophysical methods and remote techniques for characterizing the fracture network of a potentially unstable cliff site (the 'Roche du Midi', Vercors massif, France)
    Journal of Geophysics and Engineering, 2008
    Co-Authors: Jacques Deparis, Bruno Fricout, Denis Jongmans, Thierry Villemin, Laurent Effendiantz, Alex Mathy
    Abstract:

    Stability assessment of a cliff strongly depends on the fracture pattern and the face topography. Geological observations as well as classical geodetic measurements are difficult to perform on high, nearly vertical cliffs such as the ones surrounding the town of Grenoble (French Alps). In this study we combine remote and ground imaging techniques for characterizing the geometry and the fracture pattern of potentially unstable cliff sites. A dense digital surface model (DDSM) of the rock face can now be obtained from laser scanning (Lidar) or photogrammetry. These techniques are safer and quicker than direct measurements. They offer the possibility of collecting structural data and of sampling the shape of the outcrop at a centimetric resolution. We applied these two techniques to a potentially unstable site (the 'Roche du Midi', Vercors massif) for determining the main fracture families affecting the rock mass and we obtained results similar to direct measurements performed on the nearby outcrops and on the cliff face itself. The laser scanning data suffer a bias in the illumination of the site. Geophysical experiments were also conducted on the plateau and on the cliff face in order to delineate the fracture pattern inside the rock mass. ERT (electrical resistivity tomography) and GPR (ground penetrating radar) profiles were performed on the plateau and allowed near-vertical open fractures to be located in the vicinity of the surface. The best geophysical results in terms of penetration and resolution were, however, obtained from GPR profiles conducted directly on the cliff face. Laser scanning data were combined with GPR data in order to take into account the shape of the sampled profiles. The combination of vertical and short horizontal profiles allowed the strike and dip of the discontinuities to be determined. The two main families were imaged, as well as a major continuous inward dipping reflector which was not shown during the Initial Reconnaissance. Further investigation inside the mass effectively showed the existence of this fracture. These results highlight the power of the GPR technique in characterizing the discontinuity pattern inside rock mass for improving the model in view of hazard assessment.

  • Combined use of geophysical methods and remote techniques for characterizing the fracture network of a potential unstable cliff site (the “Roche du Midi”, Vercors massif, France)
    Journal of Geophysics and Engineering, 2008
    Co-Authors: Jacques Deparis, Bruno Fricout, Denis Jongmans, Thierry Villemin, Laurent Effendiantz, Alex Mathy
    Abstract:

    Stability assessment of a cliff strongly depends on the fracture pattern and the face topography. Geological observations as well as classical geodetic measurements are difficult to perform on high nearly vertical cliffs like the ones surrounding the town of Grenoble (French Alps). In this study we combine remote and ground imaging techniques for characterizing the geometry and the fracture pattern of potential unstable cliff sites. A Dense Digital Surface Model (DDSM) of the rock face can now be obtained from laser scanning (Lidar) or photogrammetry. These techniques are safer and quicker than direct measurements. They offer the possibility to collect structural data and to sample the shape of the outcrop at a centimetric resolution. We applied these two techniques to a potential unstable site (the “Roche du Midi”, Vercors massif) for determining the main fracture families affecting the rock mass and we obtained results similar to direct measurements performed on the nearby outcrops and on the cliff face itself. The laser scanning data suffers a bias in the illumination of the site. Geophysical experiments were also conducted on the plateau and on the cliff face in order to delineate the fracture pattern inside the rock mass. ERT (Electrical Resistivity Tomography) and GPR (Ground Penetrating Radar) profiles were performed on the plateau and allowed near-vertical open fractures to be located in the vicinity of the surface. Best geophysical results in terms of penetration and resolution were however obtained from GPR profiles conducted directly on the cliff face. Laser scanning data were combined with GPR data in order to take into account the shape of the sampled profiles. The combination of vertical and short horizontal profiles allowed the strike and dip of the discontinuities to be determined. The two main families were imaged, as well as a major continuous inward dipping reflector which was not shown during the Initial Reconnaissance. Further investigation inside the mass effectively showed the existence of this fracture. These results highlight the power of the GPR technique in characterizing the discontinuity pattern inside rock mass for improving the model in view of hazard assessment.

Jason Ingham - One of the best experts on this subject based on the ideXlab platform.

  • Performance of adhesive wall-to-diaphragm connections in the Canterbury earthquakes and the subsequent experimental pull-out test program
    2013
    Co-Authors: Dmytro Dizhur, Arturo E Schultz, Jason Ingham
    Abstract:

    The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the Initial Reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof or floor diaphragms appeared to have failed prematurely. These observations were more frequent for the case of adhesive anchor connections than for the case of through-bolt connections (i.e. anchorages having plates on the exterior facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragm. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation and the use of metal foil sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5 to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes and a snapshot of the performed experimental program and the test results are presented herein.

  • Experimental pull-out test program of wall-to-diaphragm adhesive connections and observations from 2010/2011 Canterbury earthquakes
    2013
    Co-Authors: Dmytro Dizhur, Josiah Campbell, Jason Ingham, Arturo E Schultz
    Abstract:

    The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the Initial Reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof or floor diaphragms appeared to have failed prematurely. These observations were more frequent for adhesive anchor connections than for through-bolt connections (i.e. anchorages having plates on the exterior facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragm. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation and the use of metal mesh sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5 to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes, a snapshot of the performed experimental program and the test results and a preliminary proposed pull-out capacity of adhesive anchors are presented herein.

  • Observations from the 2010/2011 Canterbury Earthquakes and Subsequent Experimental Pull-Out Test Program of Wall-to-Diaphragm Adhesive Connections
    2013
    Co-Authors: Dmytro Dizhur, Josiah Campbell, Arturo E Schultz, Jason Ingham
    Abstract:

    The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the Initial Reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof of floor diaphragms appeared to have failed prematurely. These observations were more frequent for adhesive anchor connections than for through-bolt connections (i.e. anchorages having plates on the exteriror facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragms. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation and the use of metal mesh sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.50 to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes, a snapshot of the performed experimental program and the test results and a preliminary proposed pull-out capacity of adhesive anchors are presented herein.

Arturo E Schultz - One of the best experts on this subject based on the ideXlab platform.

  • Performance of adhesive wall-to-diaphragm connections in the Canterbury earthquakes and the subsequent experimental pull-out test program
    2013
    Co-Authors: Dmytro Dizhur, Arturo E Schultz, Jason Ingham
    Abstract:

    The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the Initial Reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof or floor diaphragms appeared to have failed prematurely. These observations were more frequent for the case of adhesive anchor connections than for the case of through-bolt connections (i.e. anchorages having plates on the exterior facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragm. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation and the use of metal foil sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5 to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes and a snapshot of the performed experimental program and the test results are presented herein.

  • Experimental pull-out test program of wall-to-diaphragm adhesive connections and observations from 2010/2011 Canterbury earthquakes
    2013
    Co-Authors: Dmytro Dizhur, Josiah Campbell, Jason Ingham, Arturo E Schultz
    Abstract:

    The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the Initial Reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof or floor diaphragms appeared to have failed prematurely. These observations were more frequent for adhesive anchor connections than for through-bolt connections (i.e. anchorages having plates on the exterior facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragm. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation and the use of metal mesh sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.5 to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes, a snapshot of the performed experimental program and the test results and a preliminary proposed pull-out capacity of adhesive anchors are presented herein.

  • observations from the 2010 2011 canterbury earthquakes and subsequent experimental pull out test program of wall to diaphragm adhesive connections
    SESOC Journal, 2013
    Co-Authors: Dmytro Dizhu, Josiah Campbell, Arturo E Schultz, Jaso Ingham
    Abstract:

    The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the Initial Reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof of floor diaphragms appeared to have failed prematurely. These observations were more frequent for adhesive anchor connections than for through-bolt connections (i.e. anchorages having plates on the exteriror facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragms. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation and the use of metal mesh sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.50 to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes, a snapshot of the performed experimental program and the test results and a preliminary proposed pull-out capacity of adhesive anchors are presented herein.

  • Observations from the 2010/2011 Canterbury Earthquakes and Subsequent Experimental Pull-Out Test Program of Wall-to-Diaphragm Adhesive Connections
    2013
    Co-Authors: Dmytro Dizhur, Josiah Campbell, Arturo E Schultz, Jason Ingham
    Abstract:

    The connections between walls of unreinforced masonry (URM) buildings and flexible timber diaphragms are critical building components that must perform adequately before desirable earthquake response of URM buildings may be achieved. Field observations made during the Initial Reconnaissance and the subsequent damage surveys of clay brick URM buildings following the 2010/2011 Canterbury, New Zealand earthquakes revealed numerous cases where anchor connections joining masonry walls or parapets with roof of floor diaphragms appeared to have failed prematurely. These observations were more frequent for adhesive anchor connections than for through-bolt connections (i.e. anchorages having plates on the exteriror facade of the masonry walls). Subsequently, an in-field test program was undertaken in an attempt to evaluate the performance of adhesive anchor connections between unreinforced clay brick URM walls and roof or floor diaphragms. The study consisted of a total of almost 400 anchor tests conducted in eleven existing URM buildings located in Christchurch, Whanganui and Auckland. Specific objectives of the study included the identification of failure modes of adhesive anchors in existing URM walls and the influence of the following variables on anchor load-displacement response: adhesive type, strength of the masonry materials (brick and mortar), anchor embedment depth, anchor rod diameter, overburden level, anchor rod type, quality of installation and the use of metal mesh sleeve. In addition, the comparative performance of bent anchors (installed at an angle of minimum 22.50 to the perpendicular projection from the wall surface) and anchors positioned horizontally was investigated. Observations on the performance of wall-to-diaphragm connections in the 2010/2011 Canterbury earthquakes, a snapshot of the performed experimental program and the test results and a preliminary proposed pull-out capacity of adhesive anchors are presented herein.