Research article Special Issues

CPTU correlations for Norwegian clays: an update

  • Received: 19 February 2019 Accepted: 29 March 2019 Published: 26 April 2019
  • Geotechnical design in clay areas in Norway is mainly based on piezocone (CPTU) tests results. Strength and stiffness parameters are usually derived from CPTU parameters and empirical correlations. In order to improve geotechnical design practice (e.g. more cost-effective solutions) and to reduce risks related to the occurrence of catastrophic events (e.g. landslides, excavation failure) the Norwegian Geotechnical Institute (NGI) has recently updated its block sample database and worked on updating CPTU correlations for clays. This paper provides a short overview of NGI's block sample database consisting of 61 block samples data points collected from 17 Norwegian clay sites. Multiple regression analyses were used to evaluate possible correlations among CPTU parameters (e.g. excess pore pressure, Δu, net cone resistance, qnet, and effective cone resistance, qe), undrained shear strength (suC) and basic clay properties (e.g. overconsolidation ratio, OCR, plasticity, sensitivity). The target was to establish correlations characterized by low uncertainty. The most reliable assessment of undrained strength was obtained when using the Stress History and Normalized Soil Engineering Properties, SHANSEP, framework associated with the best estimate OCR profile extrapolated from the CPTU measurements. This well reflects the strong relation that suC has with OCR. Despite the high quality of the samples, high scatter was observed for some of the equations that compare cone factors and basic soil parameters. In addition to the natural variability of soil properties, other possible reason to justify the scatter is that even though the accuracy of CPTU probes has improved over the past decades, especially in terms of the ability to measure low values, the results can vary among the different manufacturers. Furthermore there may be several other soil parameters than the peak undrained strength that impacts the cone resistance, for instance stiffness and large strain behavior. Such factors can affect the correlation results.

    Citation: Priscilla Paniagua, Marco D'Ignazio, Jean-Sébastien L'Heureux, Tom Lunne, Kjell Karlsrud. CPTU correlations for Norwegian clays: an update[J]. AIMS Geosciences, 2019, 5(2): 82-103. doi: 10.3934/geosci.2019.2.82

    Related Papers:

  • Geotechnical design in clay areas in Norway is mainly based on piezocone (CPTU) tests results. Strength and stiffness parameters are usually derived from CPTU parameters and empirical correlations. In order to improve geotechnical design practice (e.g. more cost-effective solutions) and to reduce risks related to the occurrence of catastrophic events (e.g. landslides, excavation failure) the Norwegian Geotechnical Institute (NGI) has recently updated its block sample database and worked on updating CPTU correlations for clays. This paper provides a short overview of NGI's block sample database consisting of 61 block samples data points collected from 17 Norwegian clay sites. Multiple regression analyses were used to evaluate possible correlations among CPTU parameters (e.g. excess pore pressure, Δu, net cone resistance, qnet, and effective cone resistance, qe), undrained shear strength (suC) and basic clay properties (e.g. overconsolidation ratio, OCR, plasticity, sensitivity). The target was to establish correlations characterized by low uncertainty. The most reliable assessment of undrained strength was obtained when using the Stress History and Normalized Soil Engineering Properties, SHANSEP, framework associated with the best estimate OCR profile extrapolated from the CPTU measurements. This well reflects the strong relation that suC has with OCR. Despite the high quality of the samples, high scatter was observed for some of the equations that compare cone factors and basic soil parameters. In addition to the natural variability of soil properties, other possible reason to justify the scatter is that even though the accuracy of CPTU probes has improved over the past decades, especially in terms of the ability to measure low values, the results can vary among the different manufacturers. Furthermore there may be several other soil parameters than the peak undrained strength that impacts the cone resistance, for instance stiffness and large strain behavior. Such factors can affect the correlation results.


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    [1] Lunne T, Berre T, Strandvik S (1997) Sample disturbance effects in soft low plastic Norwegian clay, Proceedings of the Conference on Recent Developments in Soil and Pavement Mechanics, Rio de Janeiro, Brazil, Rotterdam: Balkema, 81–102.
    [2] Lunne T, Berre T, Andersen KH, et al. (2006) Effects of sample disturbance and consolidation procedures on measured shear strength of soft marine Norwegian clays. Can Geotech J 43: 726–750. doi: 10.1139/t06-040
    [3] Karlsrud K, Hernandez-Martinez FG (2013) Strength and deformation properties of Norwegian clays from laboratory tests on high-quality block samples. Can Geotech J 50: 1273–1293. doi: 10.1139/cgj-2013-0298
    [4] Karlsrud K, Lunne T, Kort DA, et al. (2005) CPTU correlations for clays. Proceedings of the international conference on soil mechanics and geotechnical engineering, Rotterdam: Balkema, 693–702.
    [5] Lunne T, Robertson PK, Powell JJM (1997) Cone Penetration Testing in Geotechnical Practice, London: Blackie Academic and Professional.
    [6] Robertson PK (2009) Interpretation of cone penetration tests-a unified approach. Can Geotech J 46: 1337–1355. doi: 10.1139/T09-065
    [7] L'Heureux JS, Gundersen AS, D'Ignazio M, et al. (2018) Impact of sample quality on CPTU correlations in clay – Example from the Rakkestad clay. In: Hicks, Pisanò & Peuchen (Eds), CPT18-4th International Symposium on Cone Penetration Testing. Rotterdam: CRC Press/Balkema, 395–400.
    [8] Clayton CR, Simons NE, Matthews MC (1982) Site investigation, Oxford: Blackwell Science.
    [9] Berre T, Lunne T, Andersen KH, et al. (2007) Potential improvements of design parameters by taking block samples of soft marine Norwegian clays. Can Geotech J 44: 698–716. doi: 10.1139/t07-011
    [10] Lunne T, Andersen KH (2007) Soft clay shear strength parameters for deepwater geotechnical design, Offshore Site Investigation and Geotechnics: Confronting New Challenges and Sharing Knowledge, London: Society of Underwater Technology, 1–26.
    [11] Di Buò B, Selänpää J, Länsivaara T, et al. (2018) Evaluation of sample quality from different sampling methods in Finnish soft sensitive clays. Can Geotech J.
    [12] Lefebvre G, Poulin C (1979) A new method of sampling in sensitive clay. Can Geotech J 16: 226–233. doi: 10.1139/t79-019
    [13] Nash DFT, Powell JJM, Lloyd IM (1992) Initial investigations of the soft clay test site at Bothkennar. Géotechnique 42: 163–181. doi: 10.1680/geot.1992.42.2.163
    [14] Paniagua P, L'Heureux JS, Carroll R, et al. (2017) Evaluation of sample disturbance of three Norwegian clays. In: Woojin Lee, Jong-Sub Lee, Hyun-Ki Kim, et al. (Eds), Unearth the Future, Connect beyond. Proceedings of the 19th International Conference on Soil Mechanics and Geotechnical Engineering, 481–484.
    [15] NGI (2017) SP8-Soil Parameters in Geotechnical Design (GEODIP) -Rakkestad clay-block sampling and laboratory results. NGI report 20150030-08-R.
    [16] NGI (2018) SP8-Soil Parameters in Geotechnical Design (GEODIP) -GEODIP's high-quality database: clay. NGI report 20150030-02-R.
    [17] NGI (2018) SP8-Soil Parameters in Geotechnical Design (GEODIP) -CPTU correlations for clays. NGI report 20150030-13-R.
    [18] Karlsrud K (1991) Sammenstilling av noen erfaringer med prøvetaking og effekt av prøveforstyrrelse i norske marine leire. NGI report 521500-6.
    [19] Janbu N (1969) The resistance concept applied to deformations of soils. Proceedings of the 7th International Conference on Soil Mechanics and Foundation Engineering, Mexico City, 191–196.
    [20] Donohue S, Long M (2007) Rapid Determination of Soil Sample Quality Using Shear Wave Velocity and Suction Measurements. Proceedings of the 6th International Offshore Site Investigation and Geotechnics: Confronting New Challenges and Sharing Knowledge, London: Society of Underwater Technology, 63–72.
    [21] NGF (2013) Veiledning for prøvetaking. NGF publication no. 11.
    [22] Amundsen H, Thakur V, Emdal A (2016) Sample disturbance in block samples of low plastic soft clays. Proceedings of the 17th Nordic Geotechnical Meeting Challenges in Nordic Geotechnics 25th–28th of May, 159–168.
    [23] Larsson R, Sallfors G, Bengtsson PE, et al. (2007) Skjuvhallfasthet: utvardering i kohesionsjord. Linkoping: Swedish Geotechnical Institute.
    [24] Low HE, Lunne T, Andersen KH, et al. (2010) Estimation of intact and remoulded undrained shear strengths from penetration tests in soft clays. Géotechnique 60: 843–859. doi: 10.1680/geot.9.P.017
    [25] Leroueil S, Demers D, Martel LRP, et al. (1995) Practical use of the piezocone in Eastern Canada clays. In: CPT95-1st International Symposium on Cone Penetration Testing, 515–522.
    [26] Mayne PW (1986) CPT indexing of in situ OCR in clays. Use of In Situ Tests in Geotechnical Engineering, ASCE, 780–793.
    [27] Mesri G (2001) Undrained shear strength of soft clays from push cone penetration test. Géotechnique 51: 167–168. doi: 10.1680/geot.2001.51.2.167
    [28] Powell JJ, Lunne T (2005) Use of CPTU data in clays/fine grained soils. Studia Geotechnica et Mechanica 27: 28–65.
    [29] Mayne PW (2005) Integrated ground behavior: in-situ & lab tests. Deformation Characteristics of Geomaterials, London: Taylor & Francis, 155–177.
    [30] Chen BSY, Mayne PW (1996) Statistical relationships between piezocone measurements and stress history of clays. Can Geotech J 33: 488–498. doi: 10.1139/t96-070
    [31] D'Ignazio M, Lunne T, Andersen KH, et al. (2019) Estimation of preconsolidation stress of clays from piezocone by means of high-quality calibration data. AIMS Geosci, In press.
    [32] Mayne PW, Holtz RD (1988) Profiling stress history from piezocone soundings. Soils Found 28: 16–28. doi: 10.3208/sandf1972.28.16
    [33] Ladd CC, Foott R (1974) A new design procedure for stability of soft clays. J Geotech Eng Div 100: 763–786.
    [34] DeGroot DJ (2014) Evaluation of soft clay properties from interpretation of CPTU data within a SHANSEP framework. Proc 5th International Workshop: CPTU and DMT in Soft Clays and Organic Soils, Poznan, Poland, 79–94.
    [35] Leroueil S (1996) Compressibility of clays: fundamental and practical aspects. J Geotech Eng 122: 534–543. doi: 10.1061/(ASCE)0733-9410(1996)122:7(534)
    [36] L'Heureux JS, Lindgård A, Emdal A (2019) The Tiller-Flotten research site: Geotechnical characterization of a sensitive clay deposit. AIMS Geosci, In press.
    [37] Paniagua P, L'Heureux JS, Yang S, et al. (2016) Study on the practices for preconsolidation stress evaluation from oedometer tests. Proceedings of the 17th Nordic Geotechnical Meeting Challenges in Nordic Geotechnics 25th–28th of May, 547–555.
    [38] D'Ignazio M, Phoon K, Tan SA, et al. (2016) Correlations for undrained shear strength of Finnish soft clays. Can Geotech J 53: 1628–1645. doi: 10.1139/cgj-2016-0037
    [39] Lunne T, Eidsmoen T, Gillespie D, et al. (1986) Laboratory and field evaluation on cone penetrometers. Proceedings of ASCE Specialty Conference In Situ'86: Use of In Situ Tests in Geotechnical Engineering, Blacksburg, ASCE, 714–729.
    [40] Sandven R (2010) Influence of test equipment and procedures on obtained accuracy in CPTU. CPT10-2nd International Symposium on Cone Penetration Testin, USA: Huntington Beach, CA.
    [41] Lunne T, Strandvik S, Kåsin K, et al. (2018) Effect of cone penetrometer type on CPTU results at a soft clay test site in Norway. In: Hicks, Pisanò & Peuchen (Eds), CPT18-4th International Symposium on Cone Penetration Testing, Rotterdam: CRC Press/Balkema, 417–422.
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