87 results for 2000, University of Canterbury Library, Cubrinovski, M.

  • Development and evaluation of CPT-Vs correlation for Canterbury, New Zealand soils of the shallow Christchurch and Springston formations

    McGann, C.R.; Bradley, B.A.; Cubrinovski, M.; Taylor, M.L.; Wotherspoon, L.M. (2014)

    Reports
    University of Canterbury Library

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  • The Undrained Cyclic Response of Monterey Sand in Direct Simple Shear

    Cappellaro, C.; Cubrinovski, M.; Bray, J.D.; Stringer, M.E.; Riemer, M.F.; Chiaro, G. (2016)

    Conference Contributions - Other
    University of Canterbury Library

    In 2010 and 2011 a series of earthquakes hit the central region of Canterbury, New Zealand, triggering widespread and damaging liquefaction in the area of Christchurch. Liquefaction occurred in natural clean sand deposits, but also in silty (fines-containing) sand deposits of fluvial origin. Comprehensive research efforts have been subsequently undertaken to identify key factors that influenced liquefaction triggering and severity of its manifestation. This research aims at evaluating the effects of fines content, fabric and layered structure on the cyclic undrained response of silty soils from Christchurch using Direct Simple Shear (DSS) tests. This poster outlines preliminary calibration and verification DSS tests performed on a clean sand to ensure reliability of testing procedures before these are applied to Christchurch soils.

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  • Evaluation of Liquefaction Potential of Pumiceous Deposits Through Field Testing

    Orense, R.P.; Wotherspoon, L.M.; Pender, M.J.; van Ballegooy, S.; Cubrinovski, M. (2016)

    Conference Contributions - Other
    University of Canterbury Library

    Pumice materials are frequently encountered in many engineering projects in New Zealand. Because of their lightweight, highly crushable and compressible nature, they are problematic from an engineering and construction viewpoint. However, there is very little information on the liquefaction characteristics of pumice deposits and most empirical procedures available for evaluating the liquefaction potential of sands are derived from hard-grained (quartz) sands.

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  • Ongoing development of a near-surface shear wave velocity (Vs) model for Christchurch using a region-specific CPT-Vs correlation

    McGann, C.R.; Bradley, B.A.; Cubrinovski, M. (2015)

    Conference Contributions - Other
    University of Canterbury Library

    This paper summarizes the development of a region-wide surficial shear wave velocity model based on the combination of the large high-spatial-density database of cone penetration test (CPT) logs in and around Christchurch, New Zealand and a recently-developed Christchurch-specific empirical correlation between soil shear wave velocity and CPT. The ongoing development of this near-surface shear wave velocity model has applications for site characterization efforts via the development of maps of time-averaged shear wave velocities over specific depths, and the identification of regional similarities and differences in soil shear stiffness.

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  • Advanced Soil Sampling of Silty Sands in Christchurch

    Stringer, M.E.; Taylor, M.L.; Cubrinovski, M. (2015)

    Reports
    University of Canterbury Library

    Current research in geotechnical engineering at the University of Canterbury includes a number of laboratory testing programmes focussed on understanding the behaviour of natural soil deposits in Christchurch during the 2010-2011 Canterbury Earthquake Sequence. Many soils found in Christchurch are sands or silty sands with little to no plasticity, making them very difficult to sample using established methods. The gel-push sampling methodology, developed by Kiso-Jiban Consultants in Japan, was developed to address some of the deficiencies of existing sampling techniques and has been deployed on two projects in Christchurch. Gel push sampling is carried out with a range of samplers which are modified versions of existing technology, and the University of Canterbury has acquired three versions of the tools (GP-S, GP-Tr, GP-D). Soil samples are extracted from the bottom of a freshly drilled borehole and are captured within a liner barrel, close to 1m in length. A lubricating polymer gel coats the outside of the soil sample as it enters the liner barrel. The frictional rubbing which normally occurs on the sides of the soil samples using existing techniques is eliminated by the presence of the polymer gel. The operation of the gel-push samplers is significantly more complicated than conventional push-tube samplers, and in the initial trials a number of operational difficulties were encountered, requiring changes to the sampling procedures. Despite these issues, a number of high quality soil samples were obtained on both projects using the GP-S sampler to capture silty soil. Attempts were made to obtain clean sands using a different gel-push sampler (GP-TR) in the Red Zone. The laboratory testing of these sands indicated that they were being significantly disturbed during the sampling and/or transportation procedures. While it remains too early to draw definitive conclusions regarding the performance of the gel-push samplers, the methodology has provided some promising results. Further trialling of the tools are required to refine operating procedures understand the full range of soil conditions which can be successfully sampled using the tools. In parallel with the gel-push trials, a Dames and Moore fixed-piston sampler has been used by our research partners from Berkeley to obtain soil samples at a number of sites within Christchurch. This sampler features relatively short (50cm), thin-walled liner barrels which is advanced into the ground under the action of hydraulic pressure. By reducing the overall length of the soil being captured, the disturbance to the soil as it enters the liner barrel is significantly reduced. The Dames and Moore sampler is significantly easier to operate than the gel-push sampler, and past experience has shown it to be successful in soft, plastic materials (i.e. clays and silty clays). The cyclic resistance of one silty clay obtained using both the gel-push and Dames & Moore samplers has been found to be very similar, and ongoing research aims to establish whether similar results are obtained for different soil types, including silty materials and clean sands.

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  • Relative accuracy of CPT-based liquefaction evaluation procedures: Lessons learned for the 2010-2011 Canterbury earthquake sequence

    Green, R.A.; Maurer, B.W.; Cubrinovski, M.; Bradley, B.A. (2015)

    Conference Contributions - Published
    University of Canterbury Library

    Data from the 2010-2011 Canterbury earthquake sequence (CES) provides an unprecedented opportunity to assess and advance the current state of practice for evaluating liquefaction triggering. Towards this end, select case histories from the CES are used herein to assess the predictive capabilities of three alternative CPT-based simplified liquefaction evaluation procedures: Robertson and Wride (1998); Moss et al. (2006); and Idriss and Boulanger (2008). Additionally, the Liquefaction Potential Index (LPI) framework for predicting the severity of surficial liquefaction manifestations is also used to assess the predictive capabilities of the liquefaction evaluation procedures. Although it is not without limitations, use of the LPI framework for this purpose circumvents the need for selecting “critical” layers and their representative properties for study sites, which inherently involves subjectivity and thus has been a point of contention among researchers. It was found that while all the assessed liquefaction triggering evaluation procedures performed well for the parameter ranges of the sites analyzed, the procedure proposed by Idriss and Boulanger (2008) yielded predictions that are more consistent with field observations than the other procedures. However, use of the Idriss and Boulanger (2008) procedure in conjunction with a Christchurch-specific correlation to estimate fines content showed a decreased performance relative to using a generic fines content correlation. As a result, the fines correction for the Idriss and Boulanger (2008) procedure needs further study.

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  • A high-resolution shear wave velocity model for near-surface soils in Christchurch

    McGann, C.R.; Bradley, B.A.; Cubrinovski, M. (2015)


    University of Canterbury Library

    This paper summarizes the development of a high-resolution surficial shear wave velocity model based on the combination of the large high-spatial-density database of cone penetration test (CPT) logs in and around Christchurch, New Zealand and a recently-developed Christchurch-specific empirical correlation between soil shear wave velocity and CPT. This near-surface shear wave velocity model has applications for site characterization efforts via the development of maps of time-averaged shear wave velocities over specific depths, as well as use in site response analysis and ground motion simulation.

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  • Advanced Soil Sampling of Silty Sands in Christchurch

    Stringer, M.E.; Taylor, M.L.; Cubrinovski, M. (2015)

    Reports
    University of Canterbury Library

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  • Key factors in the liquefaction-induced damage to buildings and infrastructure in Christchurch: Preliminary findings

    Cubrinovski, M.; Taylor, M.; Henderson, D.; Winkley, A.; Haskell, J.; Bradley, B.A.; Hughes, M.; Wotherspoon, L.; Bray, J.; O’Rourke, T. (2014)


    University of Canterbury Library

    The paper presents preliminary findings from comprehensive research studies on the liquefaction-induced damage to buildings and infrastructure in Christchurch during the 2010-2011 Canterbury earthquakes. It identifies key factors and mechanisms of damage to road bridges, shallow foundations of CBD buildings and buried pipelines, and highlights the implications of the findings for the seismic analysis and design of these structures.

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  • Sensitivity of predicted liquefaction-induced lateral displacements from the 2010 Darfield and 2011 Christchurch earthquakes

    Robinson, K.; Cubrinovski, M.; Bradley, B.A. (2013)


    University of Canterbury Library

    The 2010 Darfield and 2011 Christchurch Earthquakes triggered extensive liquefaction-induced lateral spreading proximate to streams and rivers in the Christchurch area, causing significant damage to structures and lifelines. A case study in central Christchurch is presented and compares field observations with predicted displacements from the widely adopted empirical model of Youd et al. (2002). Cone penetration testing (CPT), with measured soil gradation indices (fines content and median grain size) on typical fluvial deposits along the Avon River were used to determine the required geotechnical parameters for the model input. The method presented attempts to enable the adoption of the extensive post-quake CPT test records in place of the lower quality and less available Standard Penetration Test (SPT) data required by the original Youd model. The results indicate some agreement between the Youd model predictions and the field observations, while the majority of computed displacements error on the side of over-prediction by more than a factor of two. A sensitivity analysis was performed with respect to the uncertainties used as model input, illustrating the model’s high sensitivity to the input parameters, with median grain size and fines content among the most influential, and suggesting that the use of CPT data to quantify these parameters may lead to variable results.

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  • The influence of near-fault motions on liquefaction triggering during the Canterbury earthquake sequence

    Carter, L.; Green, R.A.; Bradley, B.A.; Cubrinovski, M. (2013)


    University of Canterbury Library

    The objective of this study is to examine the influence of near-fault motions on liquefaction triggering in Christchurch and neighboring towns during the 2010-2011 Canterbury earthquake sequence (CES). The CES began with the 4 September 2010, Mw7.1 Darfield earthquake and included up to ten events that triggered liquefaction. However, most notably, widespread liquefaction was induced by the Darfield earthquake and the Mw6.2, 22 February 2011 Christchurch earthquake. Of particular relevance to this study is the forward directivity effects that were prevalent in the motions recorded during the Darfield earthquake, and to a much lesser extent, during the Christchurch earthquake. A 2D variant of the Richart-Newmark fatigue theory was used to compute the equivalent number of cycles (neq) for the ground motions, where volumetric strain was used as the damage metric. This study is unique because it considers the contribution and phasing of both the fault-normal and fault-parallel components of motion on neq and the magnitude scaling factor (MSF). It was found that when the fault-normal and fault-parallel motions were treated individually, the former yielded a lower neq than the latter. Additionally, when the combined effects of fault-normal and fault-parallel components were considered, it was found that the MSF were higher than those commonly used. This implies that motions containing near-fault effects are less demanding on the soil than motions that do not. This may be one of several factors that resulted in less severe liquefaction occurring during the Darfield earthquake than the Christchurch earthquake.

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  • The undrained cyclic strength of undisturbed and reconstituted Christchurch sands

    Taylor, M.L.; Cubrinovski, M.; Bradley, B.A.; Horikoshi, K. (2013)

    Conference Contributions - Published
    University of Canterbury Library

    This paper presents insights from recent advanced laboratory testing of undisturbed and reconstituted specimens of Christchurch silty-sands. The purpose of the testing was to establish the cyclic strength of silty-sands from sites in the Central Business District (CBD), where liquefaction was observed in 4 September 2010, 22 February 2011, and 13 June 2011. Similar overall strengths were obtained from undisturbed and reconstituted tests prepared at similar densities, albeit with higher variability for the reconstituted specimens. Reconstituted specimens exhibited distinctly different response in terms of lower compressibility during initial loading cycles, and exhibited a more brittle response when large strains were mobilised, particularly for samples with high fines content. Given the lower variability in natural sample response and the possibility of age-related strength to be significant for sites not subjected to earthquakes, high quality undisturbed samples are recommended over the use of reconstituted specimens to establish the cyclic strength of natural sands.

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  • Comparison of existing CPT-Vs correlations with Canterbury-specific seismic CPT data

    McGann, C.R.; Bradley, B.A.; Cubrinovski, M.; Taylor, M.; Wotherspoon, L.W. (2014)


    University of Canterbury Library

    The abundance of cone penetration test (CPT) data from subsurface explorations in Christchurch and the surrounding areas provides a useful source of information for a characterization of the near surface shear wave velocity ( ) profile for the region. A portion of the investigations were conducted using seismic CPT, enabling the comparison of measured shear wave velocity with CPT data, and subsequently the evaluation of existing CPT- correlations for applicability to Canterbury-specific soils. The existing correlations are shown to be biased, generally over-predicting the observed with depth, thus demonstrating the need for a Canterbury-specific CPT- correlation.

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  • Evaluating the Efficacy of Paleoliquefaction Analysis Techniques Using Modern Analogs

    Maurer, B.W.; Green, R.A.; Bradley, B.A.; Cubrinovski, M. (2014)


    University of Canterbury Library

    Using case studies from the 2010-2011 Canterbury, New Zealand earthquake sequence, this study assesses the accuracies of paleoliquefaction back-analysis methods and explores the challenges, techniques, and uncertainties associated with their application. While liquefaction-based back-analyses have been widely used to estimate the magnitudes of paleoearthquakes, their uncertain efficacies continue to significantly affect the computed seismic hazard in regions where they are relied upon. Accordingly, their performance is evaluated herein using liquefaction data from modern earthquakes with known magnitudes. It is shown that when the earthquake source location and mechanism are known, back-analysis methods are capable of accurately deriving seismic parameters from liquefaction evidence. However, because the source location and mechanism are often unknown in paleoseismic studies, and because accurate interpretation is shown to be more difficult in such cases, new analysis techniques are proposed herein. An objective parameter is proposed to geospatially assess the likelihood of any provisional source location, enabling an analyst to more accurately estimate the magnitude of a liquefaction-inducing paleoearthquake. This study demonstrates the application of back-analysis methods, provides insight into their potential accuracies, and provides a framework for performing paleoliquefaction analyses worldwide.

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  • Select liquefaction case histories from the 2010-2011 Canterbury earthquake sequence

    Green, R.A.; Cubrinovski, M.; Cox, B.; Wood, C.; Wotherspoon, L.; Bradley, B.A.; Maurer, B. (2014)

    Journal Articles
    University of Canterbury Library

    The 2010–2011 Canterbury earthquake sequence began with the 4 September 2010, Mw7.1 Darfield earthquake and includes up to ten events that induced liquefaction. Most notably, widespread liquefaction was induced by the Darfield and Mw6.2 Christchurch earthquakes. The combination of well-documented liquefaction response during multiple events, densely recorded ground motions for the events, and detailed subsurface characterization provides an unprecedented opportunity to add well-documented case histories to the liquefaction database. This paper presents and applies 50 high-quality cone penetration test (CPT) liquefaction case histories to evaluate three commonly used, deterministic, CPT-based simplified liquefaction evaluation procedures. While all the procedures predicted the majority of the cases correctly, the procedure proposed by Idriss and Boulanger (2008) results in the lowest error index for the case histories analyzed, thus indicating better predictions of the observed liquefaction response.

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  • What new liquefaction can teach us about old earthquakes: Evaluating the efficacy of paleoliquefaction analytics using modern analogs

    Maurer, B.W.; Green, R.A.; Bradley, B.A.; Cubrinovski, M. (2014)

    Conference Contributions - Other
    University of Canterbury Library

    Paleoliquefaction back-analyses can be very accurate if earthquake source location & mechanism are known. Accurate analysis is more difficult if source location is unknown, but index Ef enables more intelligent estimate of causative earthquake’s location and magnitude. Framework using site-specific geotechnical analysis shown to be effective and proposed for use in paleoliquefaction studies worldwide.

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  • Liquefaction Impacts on Pipe Networks: Short Term Recovery Project No. 6

    Cubrinovski, M.; Hughes, M.; Bradley, B.; McCahon, I.; McDonald, Y.; Simpson, H.; Cameron, R.; Christison, M.; Henderson, B.; Orense, R.; O'Rourke, T. (2011)

    Reports
    University of Canterbury Library

    In the aftermath of the 22 February 2011 earthquake, the Natural Hazards Research Platform (NHRP) initiated a series of Short Term Recovery Projects (STRP) aimed at facilitating and supporting the recovery of Christchurch from the earthquake impacts. This report presents the outcomes of STRP 6: Impacts of Liquefaction on Pipe Networks, which focused on the impacts of liquefaction on the potable water and wastewater systems of Christchurch. The project was a collaborative effort of NHRP researchers with expertise in liquefaction, CCC personnel managing and designing the systems and a geotechnical practitioner with experience/expertise in Christchurch soils and seismic geotechnics.

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  • Evaluation of Liquefaction Potential Index (LPI) for Assessing Liquefaction Hazard: A Case Study in Christchurch, New Zealand

    Maurer, B.; Green, R.; Cubrinovski, M.; Bradley, B.A. (2013)

    Conference Contributions - Other
    University of Canterbury Library

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  • Performance of horizontal infrastructure in Christchurch city through the 2010-2011 Canterbury earthquake sequence

    Cubrinovski, M.; Hughes, M.; Bradley, B.A.; Noonan, J.; Hopkins, R.; McNeill, S.; English, G. (2014)

    Reports
    University of Canterbury Library

    This is an interim report from the research study performed within the NHRP Research Project “Impacts of soil liquefaction on land, buildings and buried pipe networks: geotechnical evaluation and design, Project 3: Seismic assessment and design of pipe networks in liquefiable soils”. The work presented herein is a continuation of the comprehensive study on the impacts of Christchurch earthquakes on the buried pipe networks presented in Cubrinovski et al. (2011). This report summarises the performance of Christchurch City’s potable water, waste water and road networks through the 2010-2011 Canterbury Earthquake Sequence (CES), and particularly focuses on the potable water network. It combines evidence based on comprehensive and well-documented data on the damage to the water network, detailed observations and interpretation of liquefaction-induced land damage, records and interpretations of ground motion characteristics induced by the Canterbury earthquakes, for a network analysis and pipeline performance evaluation using a GIS platform. The study addresses a range of issues relevant in the assessment of buried networks in areas affected by strong earthquakes and soil liquefaction. It discusses performance of different pipe materials (modern flexible pipelines and older brittle pipelines) including effects of pipe diameters, fittings and pipeline components/details, trench backfill characteristics, and severity of liquefaction. Detailed breakdown of key factors contributing to the damage to buried pipes is given with reference to the above and other relevant parameters. Particular attention is given to the interpretation, analysis and modelling of liquefaction effects on the damage and performance of the buried pipe networks. Clear link between liquefaction severity and damage rate for the pipeline has been observed with an increasing damage rate seen with increasing liquefaction severity. The approach taken here was to correlate the pipeline damage to LRI (Liquefaction Resistance Index, newly developed parameter in Cubrinovski et al., 2011) which represents a direct measure for the soil resistance to liquefaction while accounting for the seismic demand through PGA. Key quality of the adopted approach is that it provides a general methodology that in conjunction with conventional methods for liquefaction evaluation can be applied elsewhere in New Zealand and internationally. Preliminary correlations between pipeline damage (breaks km-1), liquefaction resistance (LRI) and seismic demand (PGA) have been developed for AC pipes, as an example. Such correlations can be directly used in the design and assessment of pipes in seismic areas both in liquefiable and non-liquefiable areas. Preliminary findings on the key factors for the damage to the potable water pipe network and established empirical correlations are presented including an overview of the damage to the waste water and road networks but with substantially less detail. A comprehensive summary of the damage data on the buried pipelines is given in a series of appendices.

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  • A model for nonlinear total stress analysis with consistent stiffness and damping variation

    Arefi, M.J.; Cubrinovski, M.; Bradley, B.A. (2012)

    Conference Contributions - Published
    University of Canterbury Library

    Paper 3408

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