摘要
拉剪应力状态极易导致岩体破坏乃至失稳,为研究节理岩体拉剪破坏规律,开展了拉剪荷载下共面非贯通节理岩体变形破坏的理论与数值计算研究。通过自定义考虑岩石统计损伤演化的Mohr-Coulomb和最大拉应力准则模型,编写力学参数服从Weibull分布的fish函数,研究了拉剪条件下非均质节理岩体的破坏模式及破坏规律,讨论了岩石均质度、法向拉应力及剪切速率对岩体破坏模式及其力学性质的影响。结果表明,(1)拉剪应力状态下节理岩体的破坏模式以张拉破坏为主,加载初期破坏位置分布散乱,随着加载和损伤演化逐渐形成带状破裂面,岩体宏观力学性质明显降低;(2)非均质性对岩体破坏影响显著,主要表现为均质度的增加,岩体由弥散型破坏向集中型破坏转变,破裂面起伏度增大,同时岩体的宏观力学性质增强并最终趋向于均质岩体;(3)低应力水平下拉应力增大不改变节理岩体以拉张破坏为主的破裂模式,但剪切破坏比例明显减少,同时岩体抗剪强度降低,破裂面的粗糙度增大;(4)剪切速率对岩体力学性质的影响显著,静态加载范围内岩体抗剪强度随剪切速率的增大而增大,且增幅越来越小。
The state of tensile-shear stress can easily lead to rock mass damage and even instability. To investigate the tensile-shear failure law of jointed rock mass, numerical simulation of rock mass containing coplanar intermittent cracks under tensile-shear test is carried out through FLAC3 D simulation software. For getting high fidelity actual conditions, Mohr-Coulomb constitutive model and maximum tensile stress criterion are amended with rock statistical damage and a function is applied to make the initial mechanical parameters obey the Weibull distribution. Then, failure modes and laws of rock mass are studied under tensile-shear loading. And the influence of homogeneous degree, normal tensile stress and shear rate on rock mass failure modes and processes, as well as its mechanical properties were discussed. The main conclusions can be drawn as follows:(1) Due to the heterogeneous characteristics of natural rock mass, the failure mode is dominated by tensile failure, with little tensile-shear mixed failure. Meanwhile, the initial rupture zones are scattered and then form a strip-shaped fracture surface. The macroscopic mechanical properties of heterogeneous rock mass are obviously weakened than homogeneous rock mass without damage evolution.(2) Heterogeneity has a significant impact on the failure process and strength of jointed rock mass. That is, with the increase of homogeneous degree, the failure mode changes from diffuse type to the concentrated, and the rupture surface roughness increases. The macroscopic strength of jointed rock mass enhances, but there is a ceiling which represents strength of the homogeneous.(3) Under the low stress level, the increase of tensile stress does not change the main rupture mode of rock mass which is tensile failure. However, the proportion of shear and mixed failure are obviously less. Meanwhile, the shear strength of rock mass decreases and the roughness of fracture surface increases.(4) The shear rate has a significant effect on the mechanical properties of rock mass. In the static loading range, the shear strength of rock mass increases with the growth of shearing rate, and the magnitude of the increase is getting smaller.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2018年第S1期9-20,共12页
Rock and Soil Mechanics
基金
中国科学院战略性先导科技专项(B类)(No.XDB10030602)
国家自然科学基金项目(No.41772341
No.41372325
No.41372323)~~
关键词
统计损伤模型
非均质
拉剪荷载
共面非贯通节理
岩体破坏
statistical damage model
heterogeneity
tensile-shear load
coplanar intermittent crack
rock mass failure
