摘要
为了研究更加合理有效、适用范围更广的岩石脆性表征方法,采用了理论分析与试验结果验证的方法,分析了脆性对于实际工程的重要意义,以及现有的基于强度特征、应力应变曲线、矿物组分、断裂韧度等的脆性指标,对其合理性及在使用中的局限性进行了总结,进一步研究了应力应变曲线对于岩石脆性的表征作用,在此基础上综合考量了峰前应力增长速率、幅度及峰后应力应变关系,提出了基于全应力-应变曲线的岩石脆性特征评价方法,并通过不同岩石单轴压缩和三轴压缩试验数据进行验证。结果表明:在单轴压缩条件下,花岗岩、砂岩、灰岩、大理岩脆性依次减小,符合脆性越大破化现象越明显的规律;在三轴压缩条件下,对于同种岩石该指标随围压的增大逐渐减小,符合岩石随围压增大而表现出的脆-延转换规律;该指标能够对不同岩石的脆性做出较为准确的评价,该指标对于复杂应力条件下的岩石也能较好地反映其脆性特征;该指标对于岩石不同应力状态下其内部性质的外部反映进行了全面考虑;该方法中所使用的参数均为常规三轴压缩试验容易获取的参数,其具有适用范围广和可操作性强的特点。研究结果可以进一步丰富和完善现有岩石脆性评价体系,对实际工程具有一定的指导意义。
In order to study a more reasonable,effective and applicable characterization method of rock brittleness,the significance of brittleness to practical engineering and the existing brittleness indicators based on strength characteristics,stress-strain curve,mineral composition,fracture toughness and so on are analyzed by using theoretical analysis and experimental result verification.The rationality and limitation in application are summarized,and the characterization of stress-strain curve on rock brittleness is studied.On this basis,comprehensively considering pre peak stress growth rate,amplitude and post peak stress-strain relationship,a method for evaluating rock brittle characteristics based on total stress-strain curve is proposed,which is verified by uniaxial and triaxial compression test data of different rocks.The result shows that(1)under uniaxial compression,the brittleness of granite,sandstone,limestone and marble decreases in turn,which conforms to the rule that the greater the brittleness is,the more obvious the breaking phenomenon is;(2)under triaxial compression,for the same kind of rock,the indicator decreases gradually with the increase of confining pressure,which conforms to the brittle-ductile transition rule of rock with the increase of confining pressure;(3)the indicator can accurately evaluate the brittleness of different rocks,it can better reflect the brittleness characteristics of the rocks under complex stress condition;(4)the indicator comprehensively considers the external reflection of internal properties of rocks in different stress states;(5)the parameters used in the method are easily obtained by conventional triaxial compression test,which has the characteristics of wide application range and strong operability.The research result can further enrich and improve the existing rock brittleness evaluation system,and has certain guiding significance for practical projects.
作者
张超
白允
安永林
汪辉平
曾兴
ZHANG Chao;BAI Yun;AN Yong-lin;WANG Hui-ping;ZENG Xing(Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Hunan University of Science and Technology,Xiangtan Hunan 411201,China;Central and Southern China Municipal Engineering Design&Research institute Co.,Ltd.,Wuhan Hubei 430010,China)
出处
《公路交通科技》
CAS
CSCD
北大核心
2021年第3期63-72,共10页
Journal of Highway and Transportation Research and Development
基金
国家自然科学基金项目(41702329)
湖南省研究生科研创新项目(CX20200994)
湖南省自然科学基金项目(2018JJ3163)
湖南省教育厅科学研究项目(18C0356,19C0736)
湖南省教育厅科研项目(20A187)。
关键词
隧道工程
岩石脆性指标
理论分析
岩石
围压
tunnel engineering
rock brittleness indicator
theoretical analysis
rock
confining pressure
