不同预制裂缝方法及长度对岩石三点弯曲试验的影响  

Effect of different notch prefabrication methods and notch lengths on rock three-point bending test

作　　者：卢浩 冯夏庭[1,3] 杨成祥[3] 张希巍[3] LU Hao;FENG Xia-ting;YANG Cheng-xiang;ZHANG Xi-wei(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,Shenyang,Liaoning 110819,China)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [2]中国科学院大学,北京100049 [3]东北大学深部金属矿山安全开采教育部重点实验室,辽宁沈阳110819

出　　处：《岩土力学》2021年第4期1115-1125,共11页Rock and Soil Mechanics

基　　金：国家重点研发计划(No.2018YFC0407006)。

摘　　要：为选择岩石三点弯曲试验合适的预制裂缝方法和裂缝长度以获得相对准确可靠的岩石I型断裂韧度KIC,并了解岩石三点弯曲宏观断裂过程和细观断裂特征,采用线切割、锯片切割和水刀切割3种方法预制花岗岩和大理岩三点弯曲梁试样直切槽裂缝,以研究不同预制裂缝方法对岩石KIC的影响,结合场发射扫描电镜比较了不同切割方法岩样的细观断裂特征,试验结果表明线切割方法对岩石KIC测试结果的影响最小。另对含无量纲裂缝长度0.1、0.2、0.3、0.4和0.5的花岗岩及大理岩试样进行试验测得岩石KIC随裂缝长度增加呈先增大后减小的趋势,建议使用a=0.3的裂缝长度进行试验以得到有代表性的岩石KIC值。岩样破坏宏观上经历变形局部化带萌生、局部化带发展、裂纹起裂、最终扩展断裂的过程,声发射过程显示岩样破坏的脆性特征明显,裂缝开口位移与声发射累计曲线趋势一致,可视为试样内部破坏发展过程的宏观表征。To select an appropriate notch prefabrication method and notch length for obtaining relatively accurate and reliable rock mode I fracture toughness(KIC),as well as to improve understanding on macro fracture process and meso-fracture characteristics in the rock three-point bending test,three methods,i.e.,wire cutting,saw blade cutting and water jet cutting were used to prefabricate notch in granite and marble specimens for three-point bending test.The comparison of micro fracture characteristics among three different cutting methods was conducted with the application of scanning electronic microscopic.The test results show that the effect of wire cutting method on KIC is the smallest.In addition,three-point bending tests on granite and marble containing dimensionless notch length of 0.1,0.2,0.3,0.4,and 0.5 show that KIC tends to increase firstly and then decrease with increasing notch length.The dimensionless notch length of a=0.3 is recommended for obtaining the representative KIC.The macroscopic failure of rock specimen undergoes a process of initiation of localization zone,development of localization zone,crack initiation,and finally fracture propagation.The acoustic emission process of rock specimen is observed with an obvious brittle characteristic,the crack opening displacement curve is consistent with the trend of cumulative acoustic emission curve,and the evolution of crack opening displacement curve can be regarded as a macroscopic characterization of the specimen internal failure development process.

关 键 词：岩石三点弯曲试验 Ⅰ型断裂韧度 预制裂缝方法 裂缝长度 断裂过程 

分 类 号：TU452[建筑科学—岩土工程]