摘要
为了更准确地模拟岩石由连续向非连续转化,降低网格依赖性,在自主开发的拉格朗日元与离散元耦合的连续-非连续方法的基础上,发展了一种内部开裂方法。模型被离散成精度较高的四边形单元,在开裂后,裂缝可沿四边形单元对角线和单元边界扩展。模拟了巴西圆盘岩样、单轴压缩岩样和静水压力下洞室围岩的变形-开裂过程。结果表明:对于巴西圆盘岩样,拉裂缝由圆盘中心向上下加载板扩展,直至贯穿岩样,拉裂缝较为平滑;对于单轴压缩岩样,剪裂缝较为平直,贯穿岩样的主剪裂缝方向与摩尔-库仑剪切面方向较为一致。由静水压力和内摩擦角对洞室围岩变形-开裂过程的影响规律可以发现:静水压力下,V形坑形成于洞室表面附近;剪裂缝向围岩内部扩展,形成狭长剪裂缝,其分布类似于剪切滑移线。静水压力越大,剪裂缝的范围越大。内摩擦角越大,剪裂缝的范围越小,狭长剪裂缝的扩展方向与环向的夹角越小。由天生桥二级水电站某洞室围岩的模拟可以发现,围岩呈现4个V形坑,这与现场观测结果基本吻合。
In order to simulate the transition of rock from continua to discontinua more accurately and reduce the mesh dependence,an element splitting method is developed based on the continuum-discontinuum method where the Lagrangian element method is coupled with discrete element method.The computational domain is discretized into high-precision quadrilateral elements;after cracking,the cracks can propagate along the diagonal lines of quadrilateral elements and the edges of triangular or quadrilateral elements.Deformation-cracking processes of the Brazilian disc rock specimen,uniaxial compression rock specimen and surrounding rocks under hydrostatic pressure are simulated.The following results are found.(1)For the Brazilian disc rock specimen,tensile cracks propagate from the center of the disc to the top and bottom until they penetrate through the disc,and the tensile cracks are relatively smooth;for the uniaxial compression rock specimen,shear cracks are relatively straight,and the direction of the main shear crack penetrating through the rock specimen is consistent with the shear plane direction obtained according to the Mohr-Coulomb criterion.(2)From the effects of hydrostatic pressure and internal friction angle on deformation-cracking processes,the following results are found.Under hydrostatic pressure,firstly,V-shaped notches appear near the cavern surface due to shear crack propagation;then,long and curved shear cracks appear due to further shear crack propagation whose distribution is similar to shear slip-lines.With an increase of hydrostatic pressure,the ranges of shear cracks increase,whereas with an increase of internal friction angle,the ranges of shear cracks decrease,and the angle between the propagation direction of the long shear crack and the annular direction decreases.(3)According to the simulation of the surrounding rock in phase-Ⅱ Tianshengqiao hydropower station,four V-shaped notches are observed,which is in a good agreement with field observation.
作者
白雪元
王学滨
舒芹
BAI Xue-yuan;WANG Xue-bin;SHU Qin(College of Mechanics and Engineering,Liaoning Technical University,Fuxin,Liaoning 123000,China;Institute of Computational Mechanics,Liaoning Technical University,Fuxin,Liaoning 123000,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2020年第7期2485-2493,2513,共10页
Rock and Soil Mechanics
基金
国家自然科学基金(No.51874162)。
关键词
网格依赖性
洞室围岩
变形-开裂过程
静水压力
内摩擦角
剪切滑移线
mesh dependence
cavern surrounding rock
deformation-cracking process
hydrostatic pressure
internal friction angle
shear slip-line
