爆破作用下预制共线裂纹的扩展机理研究

为了研究爆破作用下裂纹的扩展规律,从而进一步指导裂隙发育岩体爆破设计。试验运用深部岩石三轴动静载荷实验系统对含有预制裂纹的混凝土试件逐一加载,得到混凝土试件抗压强度;并采用高速摄像机对试件中裂纹起裂拓展过程进行全程拍摄,与加载曲线对照,得到裂纹起裂时垂向初始压力。研究表明:在一定范围内,试件所受围压越大,其裂纹起裂时所需压力越大;次裂纹的存在会使得主裂纹端部更容易在外力作用下起裂,且主裂纹内侧端部所受影响要大于外侧端部,这种影响程度的大小与次裂纹长度、裂纹间距等因素有关;围压越小、裂纹夹角越大、次裂纹长度越大、裂纹间距越小,主裂纹端部越容易起裂。

Study on the expansion mechanism of prefabricated collinear cracks under blasting

To study the law of crack propagation under blasting, further guidingthe blasting design of fractured rock mass, the deep rock triaxial dynamic and static load test system was used to load the concrete specimens with pre-cracks one by one to obtain compressive strength of the concrete specimens. The high-speed camera was used to take the whole process of crack initiation and expansion in the specimens, and compared with the loading curve. The vertical initial pressure wasobtained when crack initiation occured. The study indicatedthat within a certain range, the larger the confining pressure of the test piece, the greater the pressure required for the crack initiation will be; and the presence of the secondary crack will make the main crack end more easily to crack under the action of external force, and the influence on inner end of the main crack wasmore profound than that on the outer end. The magnitude of this influence wasrelated to the length of the secondary crack and the crack spacing. The smaller the confining pressure, the larger the crack angle will be. The larger the secondary crack length and the smaller the crack spacing, the more easily the end of the main crack startedto crack. It can be concluded that the existence of adjacent cracks rendersan effect on the stress intensity at the end of the crack, and the degree of influence wasrelated to the parameters related to the collinear crack.