细观结构的非均质性对花岗岩强度及变形影响的颗粒流模拟

Influence of meso-structure heterogeneity on granite strength and deformation with particle flow code

基于等效晶质模型建模方法,利用颗粒流软件PFC^2D实现对花岗岩细观结构的重建,开展了一系列不同围压下的花岗岩常规三轴压缩试验研究。揭示了晶体粒径分布所造成的细观结构上的非均质性和Mohr–Coulomb强度准则和Hoek–Brown强度准则中各参数的关系以及对岩石脆性的影响。研究结果表明,非均质性对岩样受压加载情况下的应力–应变曲线具有显著的影响。随着非均质因子增加,岩石由均质变为非均质,弹性模量逐渐减小,泊松比增加。随着非均质性因子的增加,岩石抗压强度减小、内聚力增加、内摩擦角减小。对同一类花岗岩而言,Mohr–Coulomb强度准则和Hoek–Brown强度准则中各参数的取值并非恒定,而是一定程度上依赖于内部的细观结构。当岩石细观结构变化时,两种强度准则中的参数也随之改变。细观结构的非均质性对岩石的脆性指标影响较大,随着非均质性因子的增加,岩石脆性指标减小。

By reconstructing the meso-structure of granite using the particle flow software PFC^2D based on the grain-based model,a series of conventional triaxial compression tests on granite under different confining pressures are carried out.The relationship between the heterogeneity of the meso-structure caused by crystal size distribution and the parameters of Mohr-Coulomb strength criterion and Hoek-Brown strength criterion as well as the brittleness of rock is revealed.The heterogeneity has a significant effect on the stress-strain curve of rock specimens under pressure loading.As the heterogeneity factor increases,the rock changes from homogeneous to heterogeneous,the elastic modulus decreases,and the Poisson’s ratio increases.As the heterogeneity factor increases,the compressive strength of the rock decreases,the cohesive force increases,and the internal friction angle decreases.For the same type of granite,the values of the Mohr-Coulomb strength criterion and the Hoek-Brown strength criterion are not constant,but depend to some extent on the internal meso-structure.When the meso-structure of the rock changes,the parameters in the two strength criteria also change.The heterogeneity of the meso-structure has a great influence on the brittleness index of rock.With the increase of heterogeneity factor,the brittleness index decreases.