平面应变岩样局部化变形场数值模拟研究

NUMERICAL SIMULATION OF LOCALIZED DEFORMATION FIELD FOR ROCK IN PLANE STRAIN STATE

在FLAC^(3D)的基础上开发了后处理程序,对应变软化岩样的剪切局部化变形场(包括:速度场、应变率场、体积应变率场及位移场)进行了数值模拟研究。考虑扩容效应后,剪切带的倾角和宽度均增加,剪应变率的局部化程度降低。剪切带倾角和宽度的增加对岩样的塑性性质影响正相反。两条共轭剪切带将岩样分割成具有整体平移特性的4个小块体,每个小块体内部的位移场是比较均匀的,而剪切带附近的位移具有较大的位移梯度。剪切应变率(或应变)局部化区域与体积应变率(或应变)的位置重合,局部化区域就是岩样最终的破坏位置。

Deformation field such as shear strain rate, volumetric strain rate, velocity and displacement for rock material undergoing elastic and strain softening stage, was studied by FLAC3D. A reprocessing code programmed by FISH was developed to show the distributed shear strain and displacement in the form of three-dimensional curved surface which contributed to understanding of strain localization phenomena. The inclination angle of shear band and its width increase as dilatation angle is increased. The extent of localized deformation decreases as dilatation effect is considered. The increase of the inclination angle of shear band and its width has an opposite influence on stress-strain curve of specimen after localization occurs. Two conjugate shear bands divide the specimen into four small blocks, which have properties of movement of rigid body. In every small block, the displacement field is uniform, and in the edge of the shear band the field has large spatial gradient. The location of shear strain rate localization coincides in position with the location of volumetric strain rate, which is the actual failure zone of rock.