(1. State Key Laboratory for Geomechanics and Deep Underground Engineering,Xuzhou,Jiangsu 221008,China;
2. School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221008,China)
Abstract:Scale effect is widely shown in defective materials while scale effect is mainly originated from material heterogeneity. However,most of the scale effect study followed the research results of negative power law of concrete strength. Through microstructure analysis,much difference exists between rock and concrete materials. Limestone was selected for experimental materials. The experiment data about uniaxial compressive strength and stress-strain curves,etc.,were obtained through uniaxial compressive tests. Based on these data,the scale effect and its influential factors for rock materials are analyzed and studied,which are different from the scaling laws of concrete materials. The research results show that the defect levels in limestone materials influence rock strength,its deformation and failure characteristics heavily. An evident representative scale exists in every heterogeneous rock materials and it is closely related with the defect structural level(defect scale itself and the ratio of defect scale to rock samples scale). Scale effect of rock materials is originated from its heterogeneity,not from the friction effect between the ends of rock sample and loading plate.
[1] 郭幕孙,胡 英,李静海. 物质转化过程中的多尺度效应[M]. 哈尔滨:黑龙江教育出版社,2002:5–16.(GUO Musun,HU Ying,LI Jinghai. Multiscale effect in material transition process[M]. Harbin:Heilongjiang Education Press,2002:5–16.(in Chinese))
[2] 倪玉山,张 琦. 混凝土断裂尺寸效应的研究进展[J]. 力学进展,1997,27(1):97–105.(NI Yushan,ZHANG Qi. Recent advances on fracture scale effect for concrete structures[J]. Advances in Mechanics,1997,27(1):97–105.(in Chinese))
[3] 徐世烺,赵国藩. 混凝土断裂韧度的概率模型研究[J]. 土木工程学报,1988,21(4):9–23.(XU Shilang,ZHAO Guofan. A study on probability model of fracture toughness of concrete[J]. China Civil Engineering Journal,1988,21(4):9–23.(in Chinese))
[4] 张敦福,李术才,李明田,等. 旋转梯度对平面裂纹的影响及其尺度效应[J]. 岩石力学与工程学报,2011,30(7):1 375–1 381. (ZHANG Dunfu,LI Shucai,LI Mingtian,et al. Influence of rotation gradient on plane crack and its scale effect[J]. Chinese Journal of Rock Mechanics and Engineering,2011,30(7):1 375–1 381.(in Chinese))
[5] BAZANT Z P,Size effect in blunt fracture:concrete,rock,metal[J]. Journal of Engineering Mechanics,1984,110(4):518–535.
[6] 张 明,卢裕杰,杨 强. 准脆性材料的破坏概率与强度尺寸效应[J]. 岩石力学与工程学报,2010,29(9):1 782–1 789.(ZHANG Ming,LU Yujie,YANG Qiang. Failure probability and strength size effect of quasi-brittle materials[J]. Chinese Journal of Rock Mechanics and Engineering,2010,29(9):1 782–1 789.(in Chinese))
[7] 王文标,黄晨光,赵红平,等. 结构破坏的尺度律[J]. 力学进展,1999,29(3):383–433.(WANG Wenbiao,HUANG Chenguang,ZHAO Hongping,et al. Scaling of structure failure[J]. Advances in Mechanics,1999,29(3):383–433.(in Chinese))
[8] 刘宝琛,张家生,杜奇中,等. 岩石抗压强度的尺寸效应[J]. 岩石力学与工程学报,1998,17(6):611–614.(LIU Baochen,ZHANG Jiasheng,DU Qizhong,et al. A study of size effect for compression strength of rock[J]. Chinese Journal of Rock Mechanics and Engineering,1998,17(6):611–614.(in Chinese))
[9] 靖洪文,苏海健,杨大林,等. 损伤岩样强度衰减规律及其尺寸效应研究[J]. 岩石力学与工程学报,2012,31(3):543–549.(JING Hongwen,SU Haijian,YANG Dalin,et al. Study of strength degradation law of damaged rock sample and its size effect[J]. Chinese Journal of Rock Mechanics and Engineering,2012,31(3):543–549.(in Chinese))
[10] 高 峰,谢和平. 脆性材料的分形统计强度理论[J]. 固体力学学报,1996,17(3):239–45.(GAO Feng,XIE Heping. Statiscally fractal strength theory for brittle materials[J]. Acta Mechanica Solida Sinica,1996,17(3):239–245.(in Chinese))
[11] 王谦源,李 晔. 分形节理岩体强度与变形尺度效应的试验研究[J]. 岩土力学,2008,29(5):1 325–1 328.(WANG Qianyuan,LI Ye. Experimental study of scale effects in strength and deformation of fractal-joint rock masses[J]. Rock and Soil Mechanics,2008,29(5):1 325–1 328.(in Chinese))
[12] 倪红梅,杨圣奇. 单轴压缩下岩石材料尺寸效应的数值模拟[J]. 煤田地质与勘探,2005,33(5):47–49.(NI Hongmei,YANG Shengqi. Numerical simulation on size effect of rock material under uniaxial compression[J]. Coal Geology and Exploration,2005,33(5):47–49.(in Chinese))
[13] 郭保华. 岩样尺度、孔道及端部摩擦效应的数值分析[J].岩石力学与工程学报,2009,28(增2):3 391–3 401.(GUO Baohua. Numerical analysis of size scale,inner hole and end restraint effects of rock samples[J]. Chinese Journal of Rock Mechanics and Engineering,2009,28(Supp.2):3 391–3 401.(in Chinese))
[14] 冯增朝,赵阳升. 岩体裂隙尺度对其变形与破坏的控制作用[J]. 岩石力学与工程学报,2008,27(1):78–83.(FENG Zengchao,ZHAO Yangsheng. Control effect of fissure scale on deformation and failure of rock mass[J]. Chinese Journal of Rock Mechanics and Engineering,2008,27(1):78–83.(in Chinese))
[15] 戚承志,钱七虎. 岩体构造层次及其力学行为[J]. 世界地震工程,2004,20(2):35–38.(QI Chengzhi,QIAN Qihu. Hierarchy of rock masses and their mechanical behavior[J]. World Earthquake Engineering,2004,20(2):35–38.(in Chinese))