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工程科学与技术:2018,50(4):41-47
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基于NDB试样的脆性岩石拉剪复合断裂行为研究
(1.四川大学 建筑与环境学院 深地科学与工程教育部重点实验室, 四川 成都 610065;2.雅砻江流域水电开发有限公司, 四川 成都 610051;3.四川大学 水力学与山区河流开发保护国家重点实验室, 四川 成都 610065;4.四川大学 水利水电学院, 四川 成都 610065)
Experimental Investigation on the Tensile-shear Fracture Behavior of Brittle Rocks Using NDB Specimens
(1.Key Lab. of Deep Underground Sci. and Eng., for Minisity of Education, College of Architecture and Environment, Sichuan Univ., Chengdu 610065, China;2.Yalong River Hydropower Development Co., Ltd., Chengdu 610051, China;3.State Key Lab. of Hydraulics and Mountain River Eng., Sichuan Univ., Chengdu 610065, China;4.College of Water Resources and Hydropower, Sichuan Univ., Chengdu 610065, China)
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投稿时间:2018-02-26    修订日期:2018-05-29
中文摘要: 岩石复合断裂机理一直是岩石力学领域的研究热点。首先,利用新提出的单边切槽深梁(NDB)试样开展从纯Ⅰ型到纯Ⅱ型全复合度加载下的砂岩复合断裂试验,获得了系列载荷复合度下的砂岩复合断裂强度及砂岩断面。其次,研究砂岩复合断裂强度与随载荷复合度的变化行为,讨论了岩石复合断裂强度特征,并使用最常用的最大切应力(MTS)准则、最小应变能密度因子(MSED)准则、最大能量释放率(MERR)准则和改进的R(IR)准则预测了砂岩复合断裂强度。最后,使用激光扫描仪获得砂岩复合断面并进行断面重构,利用分形理论定量刻画岩石复合断裂面的粗糙度,研究岩石在复合载荷作用下的内在破裂机制。结果表明:砂岩等效断裂韧度随载荷复合度的增加逐步减小,IR准则与MERR准则可很好地预测砂岩复合断裂强度,MTS和MSED准则严重高估了Ⅱ型为主的砂岩复合断裂强度;砂岩断面不同复合载荷作用下的砂岩断面分统计特征具有统计意义上的相似性,一定程度上预示着不同复合载荷作用下的砂岩试件具有相似的内在破裂机制;考虑到脆性材料的强度特点,结合复合载荷作用下裂缝扩展行为,可确定拉剪复合载荷加载下岩石内在断裂机制的确为拉破坏。
Abstract:Mixed-mode fracture is of concern in rock mechanics. To better understand the failure behavior of rocks under mixed-mode loading, several groups of mixed-mode fracture tests were conducted on sandstone using notched deep beam (NDB) specimens. In this study, the fracture loads and corresponding fracture surfaces under different mixed-mode loadings were obtained, and the relation between mixed-mode fracture strength of the sandstone specimens and loading mixity was discussed. Using three widely accepted fracture criteria (i.e., the MTS, MSED and MERR criterions), the fracture loads were theoretically estimated, and our results show that the IR-criterion and the MERR criterion agreed well with the experimental data, whereas the MTS and MSED criterions significantly over-predicted the fracture strength of the sandstone specimens for mode-Ⅱ-dominated loadings. Finally, a surface topography measurement for each rough fracture surface was conducted using a laser profilometer, and the fracture surfaces were experimentally obtained and numerically reconstructed. Using the fractal method, the mixed-mode fracture surface topography properties of these surfaces were then theoretically investigated. In our study, no obvious relationship between the fractal dimension and the initial loading mixity was observed. Therefore, the investigated surfaces were almost statistically identical. Such results emphasized that the failure mode of rocks induced by mixed-mode loading is essentially the tensile mode.
文章编号:201800179     中图分类号:    文献标志码:
基金项目:国家重点研发计划资助项目(2016YFC0600702);四川省青年科技创新研究团队资助项目(2017TD0007)
作者简介:任利(1987-),男,讲师,博士.研究方向:岩石力学与工程.E-mail:renli-scu@hotmail.com
引用文本:
任利,吴世勇,周济芳,艾婷,刘洋,张茹,张朝鹏.基于NDB试样的脆性岩石拉剪复合断裂行为研究[J].工程科学与技术,2018,50(4):41-47.
REN Li,WU Shiyong,ZHOU Jifang,AI Ting,LIU Yang,ZHANG Ru,ZHANG Zhaopeng.Experimental Investigation on the Tensile-shear Fracture Behavior of Brittle Rocks Using NDB Specimens[J].Advanced Engineering Sciences,2018,50(4):41-47.