IMAGE PROCESSING OF DEFORMATION BEHAVIOR OF PLANE STRAIN COMPRESSION SPECIMENS BASED ON BIFURCATION MECHANISM

Abstract

An image processing procedure of soil deformation behavior is presented by combining PIV (particle image velocimetry) and block-diagonalization method. Plane strain compression tests of sand specimens are conducted to observe localized deformation modes. The time variation of the velocity field of deformation is observed by PIV to make clear the formation of shear band at an early state. This verocity field is decomposed into a symmetric component and antisymmetric one, which corresponds to a bifurcation mode. The symmetric one is forming wedge (s) from the beginning to the end, while the antisymmetric one changes greatly to show the occurrence of bifurcation and the formation of shear bands.