大理岩动态劈裂拉伸断裂的实验研究

Experimental Study for Dynamic Split Tension Fracture of Marble

利用直径为100mm的Hopkinson压杆和薄圆形铝片作为波形整形器，用不同弹速径向冲击大理岩平台巴西圆盘来研究其动态拉伸强度。考虑了试样的尺寸大小及两个平台附近应力的时间不均匀性与空间不均匀性对实验结果的影响。分析了试样的最大应变率、破坏时间、破坏模式以及破坏过程中的载荷应变关系，得到了关于大理岩在高应变率下拉伸强度及弹性模量的一些结论。进一步又利用该装置径向冲击人字形切槽巴西圆盘试样，对试样的起裂时间进行了初步的研究，以便今后测试动态断裂韧度。

In order to investigate rock dynamic tension strength, the flattened Brazilian disc specimens were subjected to diametral impact compression with different projectile speed by using the split Hopkinson pressure bar of 100mm diameter, and with a thin aluminum circular plate as pulse shaper. The maximum strain rate, failure time, failure pattern and the relationship between load and strain during the failure process were analyzed. Some conclusions about the tension strength and elastic modulus of marble at high strain rate were obtained. The influence of stress nonuniformness near two flattened ends of specimen to the results of test was taken into account. Furthermore, using the same equipment, the cracked chevron notched Brazilian disc specimens were subjected to diametral impact, the fracture initiation time for the specimen was studied, which laid a foundation for dynamic fracture toughness test in the future.