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Geomechanics and Engineering
  Volume 5, Number 6, December 2013 , pages 499-517
DOI: https://doi.org/10.12989/gae.2013.5.6.499
 


Localized deformation in sands and glass beads subjected to plane strain compressions
Li Zhuang, Yukio Nakata and In-Mo Lee

 
Abstract
    In order to investigate shear behavior of granular materials due to excavation and associated unloading actions, load-controlled plane strain compression tests under decreasing confining pressure were performed under drained conditions and the results were compared with the conventional plane strain compression tests. Four types of granular material consisting of two quartz sands and two glass beads were used to investigate particle shape effects. It is clarified that macro stress-strain behavior is more easily influenced by stress level and stress path in sands than in glass beads. Development of localized deformation was analyzed using photogrammetry method. It was found that shear bands are generated before peak strength and shear band patterns vary during the whole shearing process. Under the same test condition, shear band thickness in the two sands was smaller than that in one type of glass beads even if the materials have almost the same mean particle size. Shear band thickness also decreased with increase of confining pressure regardless of particle shape or size. Local maximum shear strain inside shear band grew approximately linearly with global axial strain from onset of shear band to the end of softening. The growth rate is found related to shear band thickness. The wider shear band, the relatively lower the growth rate. Finally, observed shear band inclination angles were compared with classical Coulomb and Roscoe solutions and different results were found for sands and glass beads.
 
Key Words
    plane strain compression; unloading; stress path; particle shape; shear band; DIC analysis
 
Address
(1) Li Zhuang and In-Mo Lee: Civil, Environmental and Architectural Engineering, Korea University, Seoul 136-713, Korea;
(2) Yukio Nakata: Civil and Environmental Engineering, Yamaguchi University, Ube 755-0097, Japan.
 

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