不同加载速率下玄武岩三点弯断裂性能及破坏形貌的试验研究

对不同加载速率下的玄武岩展开了三点弯断裂试验研究,探讨了荷载一位移曲线变化规律及裂纹扩展机理,分析了试样断裂面粗糙度系数随加载速率及开裂荷载的变化关系。结果发现:当加载速率在0. 005~5mm/s范围内增加时,试样的断裂峰值荷载有增大趋势,而最大位移有不同程度减小,荷载一位移曲线的弹性阶段明显突出,上凹阶段与裂纹失稳扩展阶段有所隐退。裂缝扩展高度一定时,开裂荷载随加载速率的增加而增大,且断裂面粗糙度系数与加载速率呈显著的对数函数递减趋势;而加载速率一定时,开裂荷载随裂缝扩展高度的增加而增大。试样不同高度处的开裂荷载与断裂面粗糙度系数呈明显的幕函数递减关系。

Experimental study on three-point bending fracture performance and failure morphology of basalt under different loading rates

Three-point bending fracture experiment of basalt under different loading rates was carried out, and the variation pattern of load-displacement curve and crack propagation mechanism were discussed, The relationship among roughness coefficient of specimen fracture surface, loading rate and cracking load was analyzed. Results reveal that when loading rate increases in the range of 0. 005~5mm/s, the peak load of fracture increases, but the maximum displacement decreases to some extent. Meanwhile, the elastic stage of load-displacement curve is obvious protruding, the concave stage and the crack instability expansion stage have faded. When the crack propagation height is constant, the cracking load increases with the increase of loading rate, and the roughness coefficient of fracture surface shows a significant decreasing trend of logarithmic function with the loading rate changed. When the loading rate is constant, the cracking load increases with the increase of crack extension height when loading rate is fixed. There is obvious power function decreasing relation between roughness coefficient and cracking load at different height of specimen.