摘要
鉴于考虑拉伸截断的线性莫尔-库仑屈服准则不能考虑岩石在高应力条件下的非线性屈服特征,根据虎克-布朗本构模型,将上述屈服准则在受压区的线性屈服函数修改为非线性形式。采用3种岩爆的主应力判据,判别圆形巷道开挖之后围岩中各种级别岩爆的分布及演变规律。计算采用"先加载,后挖洞"的方式,岩石服从弹—脆—塑性本构模型。研究发现,发生高级别岩爆的单元数少于发生低级别岩爆的单元数;轻微岩爆区的形态更接近于塑性区及剪切应变增量的高值区。根据巴顿判据,发生重岩爆的单元数较多,而且主要发生的是拉伸岩爆;根据陶振宇判据,发生轻微及中等岩爆的单元数均多于根据谷明成-陶振宇判据判别的结果。上述两种判据判别的结果均表明,在不考虑拉伸岩爆的条件下,只有位于围岩内部的单元才有可能发生高级别的岩爆,而位于巷道表面的单元一般仅发生轻微岩爆。
Linear Mohr-Coulomb criterion with tension cut-off cannot consider the nonlinear yielding characteristics of rocks at high stresses.According to Hoek-Brown criterion,the linear Mohr-Coulomb criterion was modified as a nonlinear criterion in the compressive region.Three kinds of principal stress criteria of rockbursts were introduced to assess the distribution and evolution of weak,moderate and serious rockbursts in the surrounding rock of a circular tunnel,respectively.In numerical simulation,a circular tunnel is excavated after the plane strain model has reached a static equilibrium state.Rock obeys an elastic-brittle-plastic constitutive model.It is found that the number of elements occurring serious rockburst is less than that of elements occurring weak rockbursts.Regions where weak rockbursts occur are very similar to plastic zones and zones with high shear strain increments.According to Barton criterion,the area of serious rockburst zones is larger and serious rockbursts in tension predominate.The numbers of elements occurring moderate and weak rockbursts based on Tao′s criterion are greater than those based on Gu and Tao′s criterion.For rockbursts in shear,serious rockbursts occur within the surrounding rock,while weak rockbursts can occur at the surface of the tunnel.
出处
《防灾减灾工程学报》
CSCD
北大核心
2012年第2期131-137,共7页
Journal of Disaster Prevention and Mitigation Engineering
基金
国家自然科学基金项目(50974069)
国家重点基础研究发展计划项目(2010CB226803)资助
关键词
非线性屈服准则
圆形巷道
莫尔-库仑准则
虎克-布朗准则
岩爆判据
nonlinear yielding criterion
circular tunnel
Mohr-Coulomb criterion
Hoek-Brown criterion
rockburst crite-rion
