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爆破是岩土工程中广泛采用的掘进方法,岩石在爆炸载荷下的断裂特性是岩石动力学的核心问题之一。利用雷管和带裂纹的水泥砂浆试样进行爆破试验研究,采用试验–数值方法确定试样的动态断裂韧度。通过试验得到的应变信号来确定试样承受的荷载及裂纹起裂的时间,将得到的时程曲线输入有限元程序ANSYS,利用1/4节点单元计算裂尖的近场位移,进而使用位移外推法求得试样I型动态断裂应力强度因子的时程曲线。裂纹起裂时刻对应的应力强度因子值即为材料的动态断裂韧度,从而给出了在爆炸载荷下I型裂纹的动态断裂韧度测试新方法。
Blasting is widely used in geotechnical engineering. The fracture characteristics of rock under explosive load are one of the core problems of rock dynamics. The detonation test was carried out by using detonators and cracked cement mortar samples. The dynamic fracture toughness of the samples was determined by the test - numerical method. The strain signal obtained from the test is used to determine the load on the specimen and the initiation time of the crack. The obtained time history curve is input to the finite element program ANSYS, and the 1/4-node unit is used to calculate the near-field displacement of the crack tip, Time-history curve of I-type dynamic fracture stress intensity factor of sample I was deduced by the method of inference. The value of the stress intensity factor corresponding to the moment of crack initiation is the dynamic fracture toughness of the material, and a new method of testing the dynamic fracture toughness of Type I crack under explosive load is given.