动力应变局部化传播及尺寸效应数值模拟

Numerical simulation of development of dynamic strain localization and size effect

采用 FLAC-3 D模拟了应变软化岩土材料局部化剪切带的发展、扩容对剪切带倾角的影响及试件的宽度效应。随着加载时步的增加 ,彼此孤立的两个应变场逐渐靠近、叠加 ,最终形成了剪切带网络。无论端面约束强或弱 ,剪切带的倾角的数值模拟结果都与罗斯科倾角比较接近。增加试样宽度 ,剪切带的宽度增加 ,剪切带变得不平直 ;宽度越大 ,岩样上端面中点的压应力 -加载时步曲线的峰值强度越大 。

FLAC\|3D is used to model progressive development of shear bands, the influence of dilation angle on the inclination angle of shear band and the effect of width of the specimen on patterns of localized bands in strain\|softening materials etc. Using FISH embedded in standard code, a function is written so that the evolution of localization is clearly apparent from 3 dimensional curved figures. With the increment of time steps, two isolated strain fields propagate towards each other. By certain time steps, the two fields meet and interact, and in the last the networks of shear bands are developed. Whether the strong end constraint or not, the inclination angle is close to Roscoe solution. Both the width of shear band and the peak strength of compressive stress in the center of upper end of specimen increase with the width of specimen. Larger width of specimen leads to curved shear band and the compressive stress\|time steps (or axial strain) curves in elastic stage is not dependent on the width of specimen.