Engineering characterisation of Norwegian glaciomarine silt

Abstract Guidance is provided for geotechnical engineers designing civil engineering works in silty soils based on a detailed characterisation of a glaciomarine silt from Os in western Norway. It was found that these soils are susceptible to disturbance by good quality fixed piston tube sampling and care needs to be taken when using laboratory derived design parameters, particularly for consolidation and shear strength properties. A technique for assessing sample disturbance using shear wave velocity and suction measurements proved promising. Conventional techniques for determining soil strength from triaxial tests in silt are inappropriate due to the dilational nature of the material and more reliable and logical strength estimates can be made from a limiting strain criterion. Field vane data should be used with caution as measured strength, particularly remoulded values, may be high and it seems more reliable parameters can be derived from CPTU tests. One dimensional consolidation and creep of these silts can be modelled successfully by the well-known Janbu formulation. The behaviour of the Os silts does not fit easily into classical soil mechanics and published frameworks for soft soils. It seems the material is of “transitional” type and this work adds to the database of such soils which includes other natural silts and gap graded soils. For future work it is recommended that larger sample tubes (say 75 mm) with a very sharp cutting edge should be used in parallel with in situ CPTU testing.

[1]  Hiroyuki Tanaka,et al.  MAIN FACTORS GOVERNING RESIDUAL EFFECTIVE STRESS FOR COHESIVE SOILS SAMPLED BY TUBE SAMPLING , 2006 .

[2]  Michael Long,et al.  In situ shear wave velocity from multichannel analysis of surface waves (MASW) tests at eight Norwegian research sites , 2007 .

[3]  Svein Erik Ingdahl,et al.  The Upper Ordovician-Lower Silurian rocks in the Os , 1989 .

[4]  Lennart Börgesson.  Shear strength of inorganic silty soils , 1981 .

[5]  Pmv Ferreira,et al.  Problems in identifying the effects of structure and critical state in a soil with a transitional behaviour , 2006 .

[6]  N O Rygg,et al.  Rotary-pressure sounding: 20 years of experience , 1989 .

[7]  Juan M. Pestana,et al.  Unified Compression Model for Venice Lagoon Natural Silts , 2007 .

[8]  Thomas L. Brandon,et al.  Drained and Undrained Strength Interpretation for Low-Plasticity Silts , 2006 .

[9]  M. Coop,et al.  The mechanics of an Italian silt: an example of ‘transitional’ behaviour , 2006 .

[10]  N. Janbu,et al.  Soil models in offshore engineering , 1985 .

[11]  D Wijewickreme,et al.  New Sample Holder for the Preparation of Undisturbed Fine-Grained Soil Specimens for Laboratory Element Testing , 2006 .

[12]  James M. Duncan,et al.  STRESS-DEFORMATION CHARACTERISTICS OF ALASKAN SILT , 1990 .

[13]  Tom Lunne,et al.  SAMPLE DISTURBANCE EFFECTS IN SOFT LOW PLASTIC NORWEGIAN CLAY , 1997 .

[14]  Kenichi Soga,et al.  Fundamentals of Soil Behaviour , 2005 .

[15]  A. W. Skemption,et al.  The Sensitivity of Clays , 1952 .

[16]  Michael Long,et al.  Engineering characterization of estuarine silts , 2007, Quarterly Journal of Engineering Geology and Hydrogeology.

[17]  Michael Long,et al.  Rapid assessment of offshore and onshore sample quality , 2008 .

[18]  J. Mangerud,et al.  A calendar age estimate of a very late Younger Dryas ice sheet maximum in western Norway. , 2002 .

[19]  Robert M. Ebeling,et al.  Hyperbolic Stress‐Strain Parameters for Silts , 1994 .

[20]  Elmer W. Brooker,et al.  Earth Pressures at Rest Related to Stress History , 1965 .

[21]  Paolo Simonini,et al.  Mechanical behavior of silty soils of the Venice lagoon as a function of their grading characteristics , 2002 .

[22]  T. Lambe,et al.  The Strength of “Undisturbed” Clay Determined from Undrained Tests , 1964 .

[23]  Kaare Høeg,et al.  Strength of Undisturbed versus Reconstituted Silt and Silty Sand Specimens , 2000 .

[24]  Guy Lefebvre,et al.  A new method of sampling in sensitive clay , 1979 .

[25]  M. Long,et al.  Assessment of sample quality in soft clay using shear wave velocity and suction measurements , 2010 .

[26]  Pankaj Sharma,et al.  COMPARATIVE STUDY ON SAMPLE QUALITY USING SEVERAL TYPES OF SAMPLERS , 1996 .

[27]  Hiroyuki Tanaka.  Sampling and sample quality of soft clays , 2008 .

[28]  Matthew Richard Coop,et al.  Some aspects of the compressibility behaviour of a clayey sand , 2001 .

[29]  T Berre,et al.  TRIAXIAL TESTING AT THE NORWEGIAN GEOTECHNICAL INSTITUTE , 1982 .

[30]  Serge Leroueil,et al.  Characterisation and engineering properties of natural soils , 2006 .

[31]  Peter K. Robertson,et al.  Cone-penetration testing in geotechnical practice , 1997 .

[32]  Michael Long,et al.  Rapid determination of soil sample quality using shear wave velocity and suction measurements , 2007 .