考虑空间–时间域影响的岩石动态断裂韧度尺寸效应研究  

Research on the size effect of rock dynamic fracture toughness considering the influence of space-time domain

作　　者：张盛[1,2] 安定超 张旭龙 陈召 王峥 ZHANG Sheng;AN Dingchao;ZHANG Xulong;CHEN Zhao;WANG Zheng(School of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo,Henan 454001,China;Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization,Jiaozuo,Henan 454001,China)

机构地区：[1]河南理工大学能源科学与工程学院,河南焦作454001 [2]煤炭安全生产与清洁高效利用省部共建协同创新中心,河南焦作454001

出　　处：《岩石力学与工程学报》2022年第10期1981-1992,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金面上项目(51674101,52174074);国家自然科学基金青年基金项目(52004081)。

摘　　要：为探究岩石动态断裂韧度的尺寸效应,采用直径分别为50,100,150,205 mm的中心直裂纹圆盘砂岩试样在分离式霍普金森压杆系统进行动态劈裂加载试验,分析不同尺寸试样动态断裂韧度测试值随尺寸变化的规律。通过虚拟裂纹模型、理论解析,结合动态有限元,确定不同尺寸试样的断裂过程区长度、孕育时间、断裂能,提出了考虑断裂过程区的空间(断裂过程区长度)–时间(断裂过程区孕育时间)域影响的岩石动态断裂韧度确定方法。同时,利用数字图像相关方法实时监测试样表面,探究试样的破坏过程。结果表明:在试样尺寸范围内,岩石断裂韧度测试值随尺寸增加而增加,表现出明显的尺寸效应;断裂过程区长度、孕育时间随试样尺寸增加而增加,意味着贡献的储存能量随尺寸增加,这与断裂能的尺寸效应相一致,间接说明断裂韧度产生尺寸效应的原因;考虑断裂过程区空间–时间域影响,在一定程度上减小了较大尺寸试样(直径150 mm、直径205 mm)断裂韧度的尺寸效应,从整体尺寸上消除尺寸效应的方法还需进一步探究;试样裂纹扩展方向由预制裂纹裂尖向加载端进行,并在加载端形成楔形破坏区。In order to explore the size effect of rock dynamic fracture toughness,the dynamic split loading test was carried out using the split Hopkinson pressure bar(SHPB)system on the cracked straight-through Brazilian disc(CSTBD)specimens with diameters of 50,100,150 and 205 mm,respectively.The variation of the dynamic fracture toughness with the size of the specimens was analyzed.The length of fracture process zone,the incubation time and the fracture energy of the specimens with different sizes were determined by virtual crack model,theoretical analysis and dynamic finite element method.A method for determining rock dynamic fracture toughness considering space(length of fracture process zone)-time(incubation time of fracture process zone)domain was proposed.At the same time,the digital image correlation method(DICM)was used to monitor the surface of the specimens,and the failure process of the specimens was explored.The results show that the test values of the fracture toughness increase with the size,showing an obvious size effect.The length of fracture process zone and the incubation time increase with the size,indicating that the contribution of the stored energy increases with the size,which is consistent with the size effect of the fracture energy and indirectly explains the reason of the size effect of the fracture toughness.Considering the space-time domain,the size effect of the fracture toughness of larger size specimens(D=150 mm,D=205 mm)is reduced.The method to eliminate the size effect from the overall size needs to be further explored.The crack propagation direction of the specimens is from the crack tip to the loading end,and a wedge-shaped failure zone is formed at the loading end.

关 键 词：岩石力学 断裂过程区 孕育时间 动态断裂韧度 尺寸效应 虚拟裂纹 

分 类 号：TU45[建筑科学—岩土工程]