霍普金森杆冲击压缩单裂纹圆孔板的岩石动态断裂韧度试验方法  

TEST METHOD FOR ROCK DYNAMIC FRACTURE TOUGHNESS USING SINGLE CLEAVAGE DRILLED COMPRESSION SPECIMEN IMPACTED BY SPLIT HOPKINSON PRESSURE BAR

作　　者：倪敏[1,2] 苟小平[1,2] 王启智[1,3,2] 

机构地区：[1]水力学及山区河流开发保护国家重点实验室,成都610065 [2]四川大学土木工程及应用力学系,成都610065 [3]深部岩土力学与地下工程国家重点实验室,北京100083

出　　处：《工程力学》2013年第1期365-372,共8页Engineering Mechanics

基　　金：国家自然科学基金项目(51179115);博士点基金项目(200806100042)

摘　　要：对压缩单裂纹圆孔板（single cleavage drilled compression-SCDC）砂岩试样，利用分离式霍普金森压杆（SHPB）冲击加载，进行了岩石张开型（I型）动态断裂实验。分别采用2种方法确定砂岩的动态断裂韧度，第1种方法是实验一数值法：由SHPB弹性杆上应变片获得作用在试件上的加载力，然后输入有限元分析程序求得试样裂尖动态应力强度因子，对应于裂尖起裂时刻的动态应力强度因子即为材料动态断裂韧度值；第2种方法是准静态法：将载荷峰值代入静态应力强度因子公式确定动态断裂韧度。2种方法的结果差异较大，对无量纲裂纹长度α／R=0．64（A组）试样，准静态方法确定的断裂韧度值要比实验．数值法确定的断裂韧度值平均要小35％～62％；对无量纲裂纹长度α／R=1．61（B组）试样，准静态方法的计算结果比实验-数值法的计算结果平均要小72％～83％。从原理上讲，实验-数值法比准静态法能更合理地测定岩石的动态断裂韧度。The opening-mode （mode-I） dynamic fracture experiment for a sandstone was performed by using single cleavage drilled compression （SCDC） specimens impacted by split Hopkinson pressure bar （SHPB）. The dynamic fracture toughness of rock was determined by two methods respectively. The first one was the experimental-numerical method： the dynamic load history was obtained from recordings of strain gauges glued on the bars of SHPB, the load was inputted to the finite element analysis program to calculate the dynamic stress intensity factor at the crack tip of specimens, and the dynamic fracture toughness is the stress intensity factor at the time of dynamic fracture initiation; the second one was the quasi-static method： the maximum load was inputted to the formula of a static stress intensity factor to determine the dynamic fracture toughness. Large differences of results were found between the experimental-numerical method and the quasi-static method： for specimens with dimensionless crack length α/R=0.64 （group A）, the results of the quasi-static method were smaller than the results of the experimental-numerical method by 35%-62%; for specimens with dimensionless crack length α/R=1.61 （group B）, the results of the quasi-static method were smaller than the results of the experimental-numerical method by 72%-83%. In principle, the experimental-numerical method can be used to measure rock dynamic fracture toughness more reasonably than the quasi-static method.

关 键 词：压缩单裂纹圆孔板 分离式霍普金森压杆 岩石动态断裂韧度 实验-数值法 准静态法 

分 类 号：O346.1[理学—固体力学]