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开展含I型预制裂纹的花岗岩矩形试件在冲击载荷作用下的动态断裂参数的试验研究。以自行研制的能实现中低冲击加载速度的可调速落锤冲击试验机进行加载,通过高速相机搭建数据采集系统进行数据采集,采用数字散斑相关方法对试验图像数据进行分析。对岩石I型裂纹在冲击载荷作用下的位移场演化特征、裂纹动态断裂的裂尖张开位移、裂纹扩展速度、动态断裂全过程中的裂尖应力强度因子等进行了定量研究。试验结果表明:落锤与岩石试件接触后,裂尖的应力强度因子呈增加趋势,当达到某一量值时,预制裂纹开裂,后续裂纹扩展的应力强度因子大于预制裂纹初始扩展的应力强度因子。
EXPERIMENTAL STUDY ON DYNAMIC FRACTURE PARAMETERS OF GRANITE RECTANGULAR TESTS CONTAINING I-FORMED CRACKS UNDER IMPACT LOADING. The self-developed adjustable speed drop hammer impact testing machine capable of achieving medium and low impact loading speed was loaded. The data acquisition was carried out by using a high-speed camera to build a data acquisition system. The digital speckle correlation method was used to analyze the experimental image data. The evolution characteristics of rock I-type crack under impact load, crack tip open displacement of crack, crack propagation velocity and crack tip stress intensity factor in the whole process of dynamic fracture were quantitatively studied. The experimental results show that the stress intensity factor at crack tip increases with the contact of drop hammer and rock specimen. When a certain value is reached, the stress intensity factor of pre-crack and subsequent crack propagation is larger than the initial stress of pre-crack factor.