Analysis of progressive failure of pillar and instability criterion based on gradient-dependent plasticity

被引:16
作者
Wang, XB [1 ]
机构
[1] Liaoning Tech Univ, Dept Mech & Engn Sci, Fuxin 123000, Peoples R China
来源
JOURNAL OF CENTRAL SOUTH UNIVERSITY OF TECHNOLOGY | 2004年 / 11卷 / 04期
基金
中国国家自然科学基金;
关键词
instability criterion; strain softening pillar; strain localization; shear band; progressive failure; slabbing; rock burst;
D O I
10.1007/s11771-004-0092-4
中图分类号
TF [冶金工业];
学科分类号
0806 ;
摘要
A mechanical model for strain softening pillar is proposed considering the characteristics of progressive shear failure and strain localization. The pillar undergoes elastic, strain softening and slabbing stages. In the elastic staged vertical compressive stress and deformation at upper end of pillar are uniform, while in the strain softening stage there appears nonuniform due to occurrence of shear bands, leading to the decrease of load-carrying capacity. In addition, the size of failure zone increases in the strain softening stage and reaches its maximum value when slabbing begins. In the latter two stages, the size of elastic core always decreases. In the slabbing stage, the size of failure zone remains a constant and the pillar becomes thinner. Total deformation of the pillar is derived by linearly elastic Hooke's law and gradient-dependent plasticity where thickness of localization band is determined according to the characteristic length. Post-peak stiffness is proposed according to analytical solution of averaged compressive stress-average deformation curve. Instability criterion of the pillar and roof strata system is proposed analytically using instability condition given by Salamon. It is found that the constitutive parameters of material of pillar, the geometrical size of pillar and the number of shear bands influence the stability of the system; stress gradient controls the starting time of slabbing, however it has no influence on the post-peak stiffness of the pillar.
引用
收藏
页码:445 / 450
页数:6
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