摘要
工程开挖面附近卸荷扰动区的岩体,受结构面和拉应力共同影响作用,其变形和破坏具有拉剪复合特征。为研究节理岩体的拉剪力学特性,基于颗粒离散元法针对共面断续节理岩体开展了系列数值模拟研究。通过假设粒间接触的力学参数服从Weibull分布表征岩体的非均质性,探讨了非均质性、均质度、法向拉应力和节理连通率对节理岩体拉剪强度和破坏模式的影响。研究表明:拉剪应力条件下非均质性节理岩体主要沿阶梯型破裂面破坏,剪应力-水平位移曲线可以分为线性变形阶段、非线性变形阶段、峰值及峰后阶段;随均质度提高,节理岩体的剪切强度逐渐增加且提升幅度逐渐减弱,趋于均质岩体,岩体中微裂纹由弥散型分布向破裂面集中;节理岩体峰值剪切强度和法向拉应力的大小呈非线性负相关关系;岩体剪切强度随节理连通率增加而显著降低。
The rock mass in the unloading disturbance zone near the excavation face of project is affected by the structural plane and tensile stress. Deformation and failure of the rock mass are characterized by the loading combining tension and shear. However, previous studies have focused on the tensile failure and compression-shear composite failure of intact rock or rock mass. The deformation and failure behavior of rock mass under tensile and shear stress conditions was less involved. This paper aims to study the mechanical behavior of jointed rock mass under combined tension and shear condition. A series of numerical simulation studies on coplanar discontinuous jointed rock mass are carried out using particle discrete element method. It assumes that the micro mechanical parameters of the intergranular contact obey the Weibull distribution to characterize the heterogeneity of the rock mass. The influence of the heterogeneity, homogeneity, normal tensile stress and joint connectivity rate on the tensile strength and failure mode of the jointed rock mass is discussed. The research results indicate that the heterogeneous jointed rock mass is primarily destroyed along the stepped fracture surface under the condition of combined tension and shear stress. The shear stress-horizontal displacement curve can be divided into the linear deformation stage, the nonlinear deformation stage, the peak and the post-peak stage. With the increase of homogeneity degree, the shear strength of jointed rock mass increases gradually and the lifting amplitude decreases gradually, which tends to be the same as that of homogeneous rock mass and the degree of breakage of the fracture surface is reduced. The micro-cracks in the rock mass are concentrated from the diffuse distribution to the fracture surface. Peak shear strength of jointed rock mass and the magnitude of the normal tensile stress are nonlinearly and negatively correlated. With the increase of the normal tensile stress, the failure mode of the jointed rock mass is transformed from tension-shear mixed type to tension type, and the roughness of the fracture surface is increased to varying degrees. The shear strength of jointed rock mass decreases significantly with the increase of joint connectivity rate.
作者
王志文
赵海军
马凤山
刘港
郭捷
WANG Zhiwen;ZHAO Haijun;MA Fengshan;LIU Gang;GUO Jie(Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing 100029;University of Chinese Academy of Sciences, Beijing 100049)
出处
《工程地质学报》
CSCD
北大核心
2019年第5期989-999,共11页
Journal of Engineering Geology
基金
国家自然科学基金项目(41877274,41831293,41772341)资助~~
关键词
非均质
共面断续节理岩体
拉伸剪切
破裂
Heterogeneity
Coplanar intermittent jointed rock-mass
Tension-shear failure
Rock mechanics
