摘要
粗糙交叉节理广泛存在于实际岩体中,含不同角度粗糙交叉节理试样的力学破裂演化特性研究对岩体工程具有重要的指导意义。基于Barton节理轮廓曲线,通过3D打印技术制作不同角度粗糙交叉节理模型,浇筑成试样后进行单轴压缩试验,并采用DIC技术对试样表面的变形特征进行了处理与分析。结果表明:主节理倾角较大试样的单轴强度基本小于主节理倾角较小试样,主次节理夹角γ在45°~60°之间时对试样的单轴抗压强度和弹性模量影响最大;通过对DIC应变云图、节理尖端全程应变和应变率激增点分析可知,起裂主要发生在主节理上下端和次节理上端,起裂应力在峰值应力的90%至峰值阶段,屈服阶段裂隙扩展速度缓慢,快速扩展主要发生在峰后阶段;粗糙交叉节理试样的起裂方向与平直节理试样不同,节理尖端裂隙多以剪切形式存在,远端在最大主应力的作用下多演化为张拉裂隙;主节理下端的应力强度因子基本大于次节理上端,说明主节理对试样的破裂起主要作用,节理尖端的KⅡ多大于KⅠ,说明起裂扩展受剪切作用大于张拉作用。
Rough cross joints widely exist in actual rock mass.The laboratory study on the mechanical fracture evolution of specimens with rough cross joints at different angles can provide important guidance for rock mass engineering.Based on Barton joint profile,we use 3D printing to generate rough cross joint models with different angles.Then we carry out uniaxial compressive tests after pouring the specimens.The deformation characteristics of the surface are processed and analyzed by the digital image correlation(DIC)technology.The results show that the uniaxial strength of specimens with larger dips of primary joint is less than that of specimens with smaller dips.The influence on the uniaxial compressive strength and elastic modulus of the specimen is most significant when the angleγbetween the primary and secondary joints is between 45°and 60°.We analyze the obtained strain contour figures by DIC,as well as the whole range of strain of joint tips and strain rate surge points.The observations are listed as follows.The fracture initiation mainly occurs at the upper and lower ends of primary joint and the upper end of secondary joint,and the initiation stress is between 90%of the peak stress and the peak.The fracture propagation rate is slow in the yield stage,and the rapid expansion mainly occurs in the post-peak stage.The fracture initiation direction of the rough cross joint specimen is different from that of the smooth joint specimen.The fracture at the tips of joints is mostly in the form of shear,and evolves into tensile fracture under the action of maximum principal stress.The stress intensity factor at the lower end of the primary joint is larger than that at the upper end of the secondary joint,which indicates that the primary joint plays the main role in the fracture of the specimen.KⅡat the joint tipis is greater than KⅠ,which indicates that the shear effect is greater than the tensile effect on the initiation and propagation of fracture.
作者
王本鑫
金爱兵
孙浩
王树亮
WANG Ben-xin;JIN Ai-bing;SUN Hao;WANG Shu-liang(Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine,University of Science and Technology Beijing,Beijing 100083,China;School of Civil and Resources Engineering,University of Science and Technology Beijing,Beijing 100083,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2021年第2期439-450,461,共13页
Rock and Soil Mechanics
基金
国家自然科学基金(No.51674015)
中央高校基本科研业务费专项资金(No.FRF-TP-19-026A1)
中国博士后科学基金项目(No.2020M670138)
