CYCLIC SIMPLE SHEAR APPARATUS FOR LOW-STRAIN SOIL TESTS

A testing system has been developed to study the behavior of saturated sand under low-level cyclic shearing strains. The system has been used to determine threshold shear strain levels for fabric destruction in sand aged for different time periods. The system includes a special soil chamber and a direct simple shear (DSS) machine. To impose very small shearing strains, the DSS machine was designed to apply and measure horizontal deformations as small as 0.0005 mm (0.00002 in.). Data obtained to date support the results of previous investigators who performed triaxial tests on freshly deposited samples, indicating a threshold cyclic shear strain level of approximately 0.01%. At strains in excess of those levels, destruction of the sand fabric occurred, as evidenced by a reduction in shear modulus at low strain levels. Subsequent modest increases in shear modulus were observed after the specimens were allowed to recover for 24 hours and then tested again. During the recovery period, drainage valves were left open to allow for dissipation of excess pore pressures and for potential consolidation during the short aging period. The DSS system was found to work well for low strain measurements. Furthermore, since shear strains are measured directly under DSS conditions (as opposed to triaxial conditions), the DSS system shows much promise as a device for studying parameters that may influence threshold shear strain levels and fabric evolution and destruction in sands.

• Record URL:
  • https://doi.org/10.3141/1548-02
• Summary URL:
  • http://scholar.google.com/scholar_lookup?title=CYCLIC+SIMPLE+SHEAR+APPARATUS+FOR+LOW-STRAIN+SOIL+TESTS&author=H.+Miller&author=P.+de+Alba&author=K.+Baldwin&publication_year=1996
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309059178
• Supplemental Notes:
  • This paper appears in Transportation Research Record No. 1548, Small-Magnitude Measurements in Geotechnical Engineering.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Miller, H J
  • de Alba, P
  • Baldwin, K C
• Publication Date: 1996

Language

• English

Media Info

• Features: Figures; Photos; References;
• Pagination: p. 9-15
• Serial:
  • Transportation Research Record
  • Issue Number: 1548
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Direct shear tests; Equipment; Shear modulus; Shear strain; Soil tests; Strain measurement
• Old TRIS Terms: Direct simple shear testing devices; Horizontal deformations; Low strain measurements; Saturated sands
• Subject Areas: Geotechnology; Highways; I42: Soil Mechanics;

Filing Info

• Accession Number: 00731156
• Record Type: Publication
• ISBN: 0309059178
• Files: TRIS, TRB
• Created Date: Feb 3 1997 12:00AM