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P. K. Robertson - One of the best experts on this subject based on the ideXlab platform.

  • Cone Penetration Test cpt based soil behaviour type sbt classification system an update
    Canadian Geotechnical Journal, 2016
    Co-Authors: P. K. Robertson
    Abstract:

    A soil classification system is used to group soils according to shared qualities or characteristics based on simple cost-effective Tests. The most common soil classification systems used in geotechnical engineering are based on physical (textural) characteristics such as grain size and plasticity. Ideally, geotechnical engineers would also like to classify soils based on behaviour characteristics that have a strong link to fundamental in situ behaviour. However, existing textural-based classification systems have a weak link to in situ behaviour, since they are measured on disturbed and remolded samples. The Cone Penetration Test (CPT) has been gaining in popularity for site investigations due to the cost-effective, rapid, continuous, and reliable measurements. The most common CPT-based classification systems are based on behaviour characteristics and are often referred to as a soil behaviour type (SBT) classification. However, some confusion exists, since most CPT-based SBT classification systems use te...

  • evaluation of flow liquefaction and liquefied strength using the Cone Penetration Test
    Journal of Geotechnical and Geoenvironmental Engineering, 2010
    Co-Authors: P. K. Robertson
    Abstract:

    Flow liquefaction is a major design issue for large soil structures such as mine tailings impoundments and earth dams. If a soil is strain softening in undrained shear and, hence, susceptible to flow liquefaction, an estimate of the resulting liquefied shear strength is required for stability analyses. Many procedures have been published for estimating the residual or liquefied shear strength of cohesionless soils. This paper presents Cone Penetration Test-based relationships to evaluate the susceptibility to strength loss and liquefied shear strength for a wide range of soils. Case-history analyses by a number of investigators are reviewed and used with some additional case histories. Extrapolations beyond the case-history data are guided by laboratory studies and theory.

  • estimating liquefaction induced lateral displacements using the standard Penetration Test or Cone Penetration Test
    Journal of Geotechnical and Geoenvironmental Engineering, 2004
    Co-Authors: G. Zhang, P. K. Robertson, Richard W I Brachman
    Abstract:

    A semiempirical approach to estimate liquefaction-induced lateral displacements using standard Penetration Test (SPT) or Cone Penetration Test (CPT) data is presented. The approach combines available SPT- and CPT-based methods to evaluate liquefaction potential with laboratory Test results for clean sands to estimate the potential maximum cyclic shear strains for saturated sandy soils under seismic loading. A lateral displacement index is then introduced, which is obtained by integrating the maximum cyclic shear strains with depth. Empirical correlations from case history data are proposed between actual lateral displacement, the lateral displacement index, and geometric parameters characterizing ground geometry for gently sloping ground without a free face, level ground with a free face, and gently sloping ground with a free face. The proposed approach can be applied to obtain preliminary estimates of the magnitude of lateral displacements associated with a liquefaction-induced lateral spread.

  • evaluating cyclic liquefaction potential using the Cone Penetration Test
    Canadian Geotechnical Journal, 1998
    Co-Authors: P. K. Robertson, C E Wride
    Abstract:

    Soil liquefaction is a major concern for structures constructed with or on sandy soils. This paper describes the phenomena of soil liquefaction, reviews suitable definitions, and provides an update on methods to evaluate cyclic liquefaction using the Cone Penetration Test (CPT). A method is described to estimate grain characteristics directly from the CPT and to incorporate this into one of the methods for evaluating resistance to cyclic loading. A worked example is also provided, illustrating how the continuous nature of the CPT can provide a good evaluation of cyclic liquefaction potential, on an overall profile basis. This paper forms part of the final submission by the authors to the proceedings of the 1996 National Center for Earthquake Engineering Research workshop on evaluation of liquefaction resistance of soils.Key words: cyclic liquefaction, sandy soils, Cone Penetration Test

  • seismic Cone Penetration Test for evaluating liquefaction potential under cyclic loading
    Canadian Geotechnical Journal, 1992
    Co-Authors: P. K. Robertson, D J Woeller, Wdl D L Finn
    Abstract:

    Impressive progress has been made in the last 25 years in recognizing liquefaction hazards, understanding liquefaction phenomena, and analyzing and evaluating the potential for liquefaction at a site. Recent findings related to the application of the seismic Cone Penetration Test (SCPT) for the evaluation of liquefaction potential under cyclic loading are presented and discussed. The SCPT provides independent measurements of Penetration resistance, pore pressures, and shear-wave velocity in a fast, continuous, and economic manner. The current methods available for evaluating liquefaction using Penetration resistance are presented and discussed. Recent developments in the application of shear-wave velocity to evaluate liquefaction potential are discussed, and a new method based on normalized shear-wave velocity is proposed. Limited case-history data are used to evaluate and support the proposed correlation. A worked example is presented to illustrate the potential usefulness of the SCPT for evaluating liqu...

Mehmet T. Tumay - One of the best experts on this subject based on the ideXlab platform.

  • computerized Cone Penetration Test for soil classification development of ms windows software
    Transportation Research Record, 2008
    Co-Authors: Murad Y Abufarsakh, Zhongjie Zhang, Mehmet T. Tumay, Mark Morvant
    Abstract:

    Computerized MS-Windows Visual Basic software of a Cone Penetration Test (CPT) for soil classification was developed as part of an extensive effort to facilitate the implementation of CPT technology in many geotechnical engineering applications. Five CPT soil engineering classification systems were implemented as a handy, user-friendly, software tool for geotechnical engineers. In the probabilistic region estimation and fuzzy classification methods, a conformal transformation is first applied to determine the profile of soil classification index (U) with depth from Cone tip resistance (qc) and friction ratio (Rf). A statistical correlation was established in the probabilistic region estimation method between the U index and the compositional soil type given by the Unified Soil Classification System. Conversely, the CPT fuzzy classification emphasizes the certainty of soil behavior. The Schmertmann and Douglas and Olsen methods provide soil classification charts based on Cone tip resistance and friction ra...

  • development of a continuous intrusion miniature Cone Penetration Test system for subsurface explorations
    Soils and Foundations, 2001
    Co-Authors: Mehmet T. Tumay, Pradeep Kurup
    Abstract:

    This paper describes the development of a continuous intrusion miniature Cone Penetration Test system (CIMCPT) or shallow to semi-deep subsurface investigations. A novel feature of this new in situ Testing system is the chain driven caterpillar-type continuous push device powered by a hydraulic motor to advance the Cone penetrometer, which greatly increases productivity and serviceability. The system is housed in an environmentally controlled van body that is mounted on a one-ton, four-wheel drive, all-terrain vehicle. A new state-of -the-art data acquisition system using interface modules and a global positioning system, for real-time monitoring, acquiring, storing, and displaying data in real time on a computer screen in graphic form was developed and implemented. The miniature Cone penetrometer has a projected Cone area of 2sq cm and a friction sleeve surface area equal to 40sq cm, It gives finer detailed soil profiles compared to the standard 10sq cm cross-sectional area reference Cone penetrometer. In situ calibration of the CIMCPT system with the standard 10sq cm Cone penetrometer indicated that the average tip resistance of the CIMCPT was 11 percent higher than that of the standard Cone penetrometer. The average CIMCPT sleeve friction was 11 percent lower than that of the standard Cone penetrometer. (A)

  • prediction of bearing capacity of friction piles in soft louisiana soils by Cone Penetration Test
    Transportation Research Record, 1999
    Co-Authors: Murad Y Abufarsakh, Hani H Titi, Mehmet T. Tumay
    Abstract:

    A comparison of four different methods for predicting the axial compression capacity of single piles using Cone Penetration Test (CPT) results is presented. Nineteen pile load Tests and parallel CPT soundings conducted close to the piles were identified and documented from the Louisiana Department of Transportation and Development archives. Piles with different sizes and lengths were investigated. The four prediction methods selected were the Schmertmann method, the de Ruiter and Beringen method, the French Central Bridge and Pavement Laboratory (LCPC) method, and the Tumay and Fakhroo method. An evaluation scheme was performed using these methods to assess their capability to reliably predict the axial compression capacity of piles installed in soft Louisiana soils. The predicted pile capacities obtained by the different methods were compared with the measured pile capacities obtained from pile load Tests. Analysis of the results showed that the Schmertmann, de Ruiter and Beringen, and Tumay and Fakhroo methods predicted the ultimate compression capacities of piles installed in soft Louisiana soils with a reasonable accuracy. The LCPC method underpredicted the measured capacities of these piles.

William Craig - One of the best experts on this subject based on the ideXlab platform.

  • development of centrifuge Cone Penetration Test to evaluate the undrained shear strength profile of a model clay bed
    Soils and Foundations, 1995
    Co-Authors: Kazuo Tani, William Craig
    Abstract:

    ABSTRACT Physical modeling utilizing a centrifuge is often attempted in order to investigate short-term stability problems of soft clay deposits whose undrained shear strength generally varies with depth. Since accurate evaluation of the strength profile in model beds is essential for such studies, a Cone Penetration Test (CPT) technique in the centrifuge has been developed to obtain geotechnical information continuously with depth. A series of CPTs in homogeneous clay beds was conducted in order to establish the correlation between Cone resistance qc and undrained shear strength cu. This empirical relationship can take account of the influences of Penetration rate, stress level and the error associated with the stress acting on the rear of the Cone tip. In the end, this CPT technique in the centrifuge has proved itself to be useful in evaluating the undrained shear strength profile in non-homogeneous clay beds.

Shane Donohue - One of the best experts on this subject based on the ideXlab platform.

  • characterization of norwegian marine clays with combined shear wave velocity and piezoCone Cone Penetration Test cptu data
    Canadian Geotechnical Journal, 2010
    Co-Authors: Michael Longm Long, Shane Donohue
    Abstract:

    A database of research-quality piezoCone Cone Penetration Test (CPTU) and shear wave velocity, Vs, information for Norwegian marine clays has been assembled to study the small-strain stiffness rela...

  • characterization of norwegian marine clays with combined shear wave velocity and piezoCone Cone Penetration Test cptu data
    Canadian Geotechnical Journal, 2010
    Co-Authors: Michael Longm Long, Shane Donohue
    Abstract:

    A database of research-quality piezoCone Cone Penetration Test (CPTU) and shear wave velocity, Vs, information for Norwegian marine clays has been assembled to study the small-strain stiffness relationships for these materials and to examine the potential use of CPTU and Vs data in combination for the purposes of characterizing these soils. Data for sites where high-quality block sampling was carried out have mostly been used. Improvements have been suggested to existing correlations between the small-strain shear modulus, Gmax, or Vs and index properties for these soils. Recent research has shown that CPTU corrected Cone tip resistance, qt, and especially the pore pressure measured during CPTUs, u2, and Vs can be measured reliably and repeatably and are not operator or equipment dependant. Therefore, a new soil classification chart involving the normalized Cone resistance, Qt, and normalized shear wave velocity, Vs1, or Vs1 and Δu/σv0′ (where u is the pore-water pressure and σv0′ is the in situ vertical ...

  • The use of the Cone Penetration Test to derive parameters for shallow foundation design
    2005
    Co-Authors: Kenneth Gavin, Brendan C. O'kelly, Abid Adekunte, Shane Donohue
    Abstract:

    In uncemented sands, the second part of Equation 1 reduces to zero, and the non geometrical variables are the bearing capacity factors. As noted by Randolph et. al. (2003), the accuracy with which bearing capacity factors for a given soil can be determined has increased substantially in recent years (See Martin 2003), and the main uncertainty in the implementation of equation 1, lies in the choice of an appropriate friction angle. The primary complication being the difficulty in sampling cohesionless soils to allow strength Testing on representative samples, and the stress-dependent effects on choice of friction angle. To overcome some of these problems greater reliance is being placed on in-situ Tests such as the Cone Penetration Test (CPT) to derive engineering parameters such as the friction angle, or through the use of empirical formulae to estimate the bearing capacity of the soil. Randolph et al. (2003) summarise the results of Tests performed on shallow foundations, and buried piles in the laboratory and field, and reported ratios of the bearing pressure (q) at displacements of 5 and 10% of the foundation diameter, normalized by the CPT end resistance (qc). The data suggest q/qc ratios of 0.09–0.16 at displacements of 5% of the foundation diameter, increasing to 0.13-0.21 at 10%. Due to the relatively large ultimate bearing resistance of sand, actual foundations are usually remote from failure and the designer is primarily concerned with estimating the settlement of the footing under working stress conditions. This is typically achieved by assuming that in this stress range, the foundation response can be assumed to be linear-elastic. Once again the key difficulty for the designer is the choice ABSTRACT:

Alireza Salehi - One of the best experts on this subject based on the ideXlab platform.

  • Cone Penetration Test in stiff over soft clay in centrifuge Test
    ASME 2019 38th International Conference on Ocean Offshore and Arctic Engineering OMAE 2019, 2019
    Co-Authors: Yuxia Hu, Mark Cassidy, Alireza Salehi
    Abstract:

    This paper describes a numerical study on soil characterization of stiff over soft clays in centrifuge Test using Cone Penetration Test (CPT), especially when the top stiff layer is thin relative to the centrifuge Cone size. An extensive parametric study was conducted using large deformation finite element (LDFE) analysis, with the Cone penetrating continuously from the soil surface. The LDFE model has been validated against existing physical Test data with very good agreement. Since the bottom soft clay was normally thick enough to fully mobilise the ultimate Cone resistance, its undrained shear strength can be interpreted by the existing approach for Cone deep Penetration in a uniform clay layer. Thus, the challenge was to interpret the strength of the top stiff layer, where the layer thickness was not thick enough to fully mobilise its ultimate resistance. Both top layer thickness ratios (to the Cone diameter) and layer strength ratios were considered in the parametric study. Based on the results from LDFE analyses, the interpretation formula of the undrained shear strength in the top stiff layer was proposed as a set of new bearing factors. The proposed Cone bearing factor was a function of the ratio of the measured peak Cone resistance in the top layer to the stable/ultimate Cone resistance in the bottom layer and the ratio between the top layer thickness to the Cone diameter. The formula can be used directly when the top layer thickness was known based on the sample preparation. However, the layer interface can be identified based on the study here, if the top layer thickness was not certain. A design flow chart was provided for interpretations of top clay layer strength and top layer thickness based on the Cone resistance profile obtained from CPT Test.