Shear strength anisotropy of natural London Clay

This paper reports the shear strength anisotropy of the natural, highly overconsolidated, London Clay from Hea- throw Terminal 5 as established by comprehensive hollow cylinder apparatus (HCA) testing. Multiple high-quality block samples from 5.2 m and 10.5 m below ground level provided samples for suites of undrained stress-path shear tests performed after consolidation to effective stress states similar to those estimated in situ. The direction of the major principal stress axis, Æ (or of the principal stress increment, Æd), and relative magnitude of the intermediate principal stress, b (2 2 3)/(1 2 3), were chosen as the controlled stress-related variables and their influence on the peak shear strength was investigated. Strong shear strength anisotropy was proven, and a potential effect of the parameter b was also detected. With b 0.5, for example, a minimum was noted in peak q/p9 at around Æ 45–678, and the maximum value, which was larger by some 40%, developed at Æ 08. A limited set of data obtained with larger test specimens suggested a possibility that loading with Æ 908 could also lead to relatively low shear strength. The pre-failure pore water pressure development reflected anisotropy of the deformation characteristics at smaller strains and contributed to the total-stress undrained shear strength anisotropy. Regarding the influence of b, the Mohr–Coulomb failure line passing through the data for b 0 or 1 provided a lower bound of all the data for a given value of Æ. The investigation of anisotropy was extended to deeper horizons of the stratum through profiling tests involving triaxial extension and simple shear conditions. Although the results confirmed the general patterns of anisotropy observed at 5.2 and 10.5m below ground level, the degree of anisotropy appeared to become stronger with depth. (A)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00168505
• Authors:
  • NISHIMURA, S
  • MINH, N A
  • JARDINE, R J
• Publication Date: 2007-2

Language

• English

Media Info

• Pagination: 49-62
• Serial:
  • Geotechnique
  • Volume: 57
  • Issue Number: 1
  • Publisher: Thomas Telford Limited
  • ISSN: 00168505

Subject/Index Terms

• TRT Terms: Airports; Clay; Data collection; Equipment; General surface features of the earth; Geomorphology; Isotropy; Loads; Mathematical models; Samples; Shear strength; Strength of materials; Tests; Torsion
• Uncontrolled Terms: Stress (Applied load)
• ITRD Terms: 1037: Airport; 4177: Clay; 8623: Data acquisition; 3674: Equipment; 5917: Isotropic; 5567: Load; 6473: Mathematical model; 6251: Sample (mater); 5531: Shear; 5544: Strength (mater); 4076: Structure (geomorphol); 6255: Test; 5512: Torsion
• Subject Areas: Aviation; Geotechnology; Terminals and Facilities; I40: Soils and Rocks; I42: Soil Mechanics; I43: Rock Mechanics;

Filing Info

• Accession Number: 01055004
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Aug 6 2007 2:17PM