Specimen Size and Scale Effects of Direct Shear Box Tests of Sands

2006 ◽  
Vol 29 (6) ◽  
pp. 100312 ◽  
Author(s):  
L David Suits ◽  
TC Sheahan ◽  
AB Cerato ◽  
AJ Lutenegger
Keyword(s):  
Scale Effects ◽  
Specimen Size ◽  
Direct Shear ◽  
Shear Box

Ballast Direct Shear Testing

2014 ◽  
Author(s):  
Timothy D. Stark ◽  
Robert H. Swan ◽  
Zehong Yuan
Keyword(s):  
Shear Strength ◽  
Test Procedure ◽  
Strength Properties ◽  
Specimen Size ◽  
Direct Shear ◽  
Shear Strength Parameters ◽  
Railroad Track ◽  
Dead Weight ◽  
Shear Box ◽  
Direct Shear Testing

This paper summarizes the appropriate equipment and test procedure for ballast shear strength testing using the direct shear method (ASTM D3080 and D5321) and presents some typical results. To accomplish this ballast testing, a full-scale direct shear box was developed that can accommodate an approximately 1 m (3 feet) wide and 0.6 m (2 feet) deep specimen, which is much larger than current shear boxes used for ballast testing. This larger specimen size resulted in significant differences in measured shear behavior and shear strength parameters. The shear strength properties of the ballast under typical as-placed conditions are determined herein using the new shear box and normal stresses applied through dead weight loading that are representative of railroad track conditions. Effects of direct shear specimen size and confining normal stress are demonstrated using a typical angular granite ballast and the results are compared to published ballast shear strength data.

scholarly journals Time-Dependent Response of a Recycled C&D Material-Geotextile Interface under Direct Shear Mode

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3070
Author(s):  
Fernanda Bessa Ferreira ◽  
Paulo M. Pereira ◽  
Castorina Silva Vieira ◽  
Maria de Lurdes Lopes
Keyword(s):  
Shear Stress ◽  
Stress Relaxation ◽  
Shear Displacement ◽  
Time Dependent ◽  
Shear Behaviour ◽  
Displacement Rate ◽  
Shear Mode ◽  
Direct Shear ◽  
Constant Displacement ◽  
Shear Box

Geosynthetic-reinforced soil structures have been used extensively in recent decades due to their significant advantages over more conventional earth retaining structures, including the cost-effectiveness, reduced construction time, and possibility of using locally-available lower quality soils and/or waste materials, such as recycled construction and demolition (C&D) wastes. The time-dependent shear behaviour at the interfaces between the geosynthetic and the backfill is an important factor affecting the overall long-term performance of such structures, and thereby should be properly understood. In this study, an innovative multistage direct shear test procedure is introduced to characterise the time-dependent response of the interface between a high-strength geotextile and a recycled C&D material. After a prescribed shear displacement is reached, the shear box is kept stationary for a specific period of time, after which the test proceeds again, at a constant displacement rate, until the peak and large-displacement shear strengths are mobilised. The shear stress-shear displacement curves from the proposed multistage tests exhibited a progressive decrease in shear stress with time (stress relaxation) during the period in which the shear box was restrained from any movement, which was more pronounced under lower normal stress values. Regardless of the prior interface shear displacement and duration of the stress relaxation stage, the peak and residual shear strength parameters of the C&D material-geotextile interface remained similar to those obtained from the conventional (benchmark) tests carried out under constant displacement rate.

Large Scale Laboratory Direct Shear Tests on Ice

1975 ◽  
Vol 12 (2) ◽  
pp. 169-178 ◽  
Author(s):  
W. D. Roggensack
Keyword(s):  
Large Scale ◽  
Stress Conditions ◽  
Direct Shear ◽  
Shear Tests ◽  
Principal Stresses ◽  
Lake Ice ◽  
Direct Shear Tests ◽  
Strength Determination ◽  
Crystal Diameter ◽  
Shear Box

This paper presents the results of a series of large scale direct shear tests performed on lake ice. Test specimens were oriented with the principal stresses acting in the plane of the ice sheet, approximately normal to the long axes of the columnar crystals. Sample dimensions were large in comparison with mean crystal diameter, reducing the possibility of deviations introduced by size effects. Although a number of assumptions are made concerning stress conditions at failure, results for uniform, artificially ‘seeded’ test pond ice indicate a failure mechanism that is frictional and consistent with triaxial test data reported elsewhere. Post-peak shear resulted in the formation of a distinct failure zone that also displayed a frictional response. The direct shear test described is robust and simple, does not require elaborate sample preparation, and may present an alternative method of strength determination for ice mechanics problems where the shear box configuration duplicates field stress conditions and constraints.

Design of a 720-mm Square Direct Shear Box and Investigation of the Impact of Boundary Conditions on Large-Scale Measured Strength

2020 ◽  
Vol 43 (6) ◽  
pp. 20190344
Author(s):  
Sandra Linero Molina ◽  
Leonie Bradfield ◽  
Stephen G. Fityus ◽  
John V. Simmons ◽  
Arcesio Lizcano
Keyword(s):  
Boundary Conditions ◽  
Large Scale ◽  
Direct Shear ◽  
Shear Box ◽  
The Impact ◽  
Measured Strength
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