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| EXPERIMENTAL STUDY OF JINPING II HYDROPOWER STATION MARBLE UNDER LOADING AND UNLOADING STRESS PATHS |
| LI Xinping1，XIAO Taoli1，2，WANG Bin1，3，XU Pengcheng1，4 |
(1. Key Laboratory of Roadway Bridge and Structure Engineering，Wuhan University of Technology，Wuhan，Hubei 430070，China；
2. School of Urban Construction，Yangtze University，Jingzhou，Hubei 434023，China；3. Changjiang Institute of Survey，
Planning，Design and Research，Changjiang Water Resources Commission，Wuhan，Hubei 430010，China；
4. Sinohydro Group Ltd.，Beijing 100048，China) |
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Abstract In light of that the surrounding rock mass of diversion tunnel group of Jinping II hydropower station lies in the condition of high geostress，two different unloading tests of marble from the diversion tunnel were carried out. In order to analyze rock strength characteristics，deformation behavior and fracture mechanism under different stress paths，the conventional triaxial compression tests of marble were also performed. The results show that：(1) Even if the stress path and initial confining pressure are different，but as long as the real-time confining pressure is the same，the peak strength is equal. (2) The peak strength increases as the initial confining pressure increases. Comparing with triaxial compression test，it decreases by 19.5% of unloading confining pressure at pre-peak，and the peak strength appears when the real-time confining pressure accounts for about 97.2% of the initial confining pressure during the post-peak test. (3) The cohesion c decreases and the internal friction angle increases at pre-peak test，compared with the post-tests. The value of c decreases about 27.5% and increases about 22.6% at pre-peak test，but the value of c increases about 13.7% and decreases about 6.5% at pre-peak test. (4) From the unloading point to strain softening stage，the stress-strain curves have obvious strain platforms，which is the characteristics of the ideal plastic deformation. The strain platform increases with the confining pressure，which shows the feature of the marble from brittleness to plastic when the confining pressure increases. (5) The unloading confining pressure test at pre-peak shows that the marble expansion is limited. (6) The fracture mode is mainly the single shear fracture for the triaxial compression test and post-peak test；and the fracture mode of the pre-peak test is the splitting failure—X conjugate shear rupture—single shear fracture as the confining pressure increases. These conclusions reveal the loading and unloading mechanical properties of marble under high geostress and provide reliable theoretical reference for the numerical simulation about excavation and design for the stability analysis of deep diversion tunnels in West China.
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Received: 10 November 2011
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| [1] 李建林. 卸荷岩体力学[M]. 北京：中国水利水电出版社，2003：5–7.(LI Jianlin. Unloading rock mass mechanics[M]. Beijing：China Water Power Press，2003：5–7.(in Chinese))
[2] 汪 斌，朱杰兵，邬爱清，等. 锦屏大理岩加、卸载应力路径下力学性质试验研究[J]. 岩石力学与工程学报，2008，27(10)：2 138– 2 145.(WANG Bin，ZHU Jiebing，WU Aiqing，et al. Experimental study of mechanical properties of Jinping marble under loading and unloading stress paths[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(10)：2 138–2 145.(in Chinese))
[3] 黄润秋，黄 达. 高地应力条件下卸荷速率对锦屏大理岩力学特性影响规律试验研究[J]. 岩石力学与工程学报，2010，29(1)：21–33.(HUANG Runqiu，HUANG Da. Experimental research on affection laws of unloading rates on mechanical properties of Jinping marble under high geostress[J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(1)：21–33.(in Chinese))
[4] 李宏哲，夏才初，闫子舰，等. 锦屏水电站大理岩在高应力条件下的卸荷力学特性研究[J]. 岩石力学与工程学报，2007，26(10)：2 104–2 109.(LI Hongzhe，XIA Caichu，YAN Zijian，et al. Study of marble unloading mechanical properties of Jinping Hydropower Station under high geostress conditions[J]. Chinese Journal of Rock Mechanics and Engineering，2007，26(10)：2 104–2 109.(in Chinese))
[5] 刘豆豆. 高地应力下岩石卸载破坏机制及其应用研究[博士学位论文][D]. 济南：山东大学，2008.(LIU Doudou. Research on unloading failure mechanism of rock under high stress and its application[Ph. D. Thesis][D]. Jinan：Shandong University，2008.(in Chinese))
[6] 高春玉，徐 进，何 鹏，等. 大理岩加卸载力学特性的研究[J]. 岩石力学与工程学报，2005，24(3)：456–460.(GAO Chunyu，XU Jin， HE Peng，et al. Study of mechanical properties of marble under loading and unloading conditions[J]. Chinese Journal of Rock Mechanics and Engineering，2005，24(3)：456–460.(in Chinese))
[7] LI J L，WANG L H，WANG X X，et al. Research on unloading nonlinear mechanical characteristics of jointed rock masses[J]. Journal of Rock Mechanics and Engineering，2010，2(4)：357–364.
[8] 张黎明，王在泉，宋全锋，等. 粉砂岩卸荷破坏全过程的试验研究[J]. 岩石力学与工程学报，2005，24(增1)：5 043–5 047. (ZHANG Liming，WANG Zaiquan，SONG Quanfeng，et al. Experimental study on the total failure course of silt sand under unloading condition[J]. Chinese Journal of Rock Mechanics and Engineering，2005，24(Supp.1)：5 043–5 047.(in Chinese))
[9] 黄润秋，黄 达. 卸荷条件下花岗岩力学特性试验研究[J]. 岩石力学与工程学报，2008，27(11)：2 205–2 213.(HUANG Runqiu，HUANG Da. Experimental research on mechanical properties of granites under unloading condition[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(11)：2 205–2 213.(in Chinese))
[10] 吕颖慧，刘泉声，胡云华. 基于花岗岩卸荷试验的损伤变形特征及其强度准则[J]. 岩石力学与工程学报，2009，28(10)：2 096–2 102. (LU Yinghui，LIU Quansheng，HU Yunhua. Damage deformation characteristics and its strength criterion based on unloading experiments of granites[J]. Chinese Journal of Rock Mechanics and Engineering，2009，28(10)：2 096–2 102.(in Chinese))
[11] 刘 建，李建朋. 砂岩高应力峰前卸围压试验研究[J]. 岩石力学与工程学报，2011，30(3)：473–479.(LIU Jian，LI Jianpeng. Experimental research on sandstone pre-peak unloading process under high confining pressure[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(3)：473–479.(in Chinese))
[12] 周宏伟，谢和平，左建平，等. 赋存深度对岩石力学参数影响的实验研究[J]. 科学通报，2010，55(34)：3 276–3 284.(ZHOU Hongwei，XIE Heping，ZUO Jianping，et al. Experimental study of the effect of depth on mechanical parameters of rock[J]. Chinese Science Bulletin，2010，55(34)：3 276–3 284.(in Chinese))
[13] OLSSON W A. The compressive strength of tuff as a function of strain rate from 10－6 to 103/s[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1991，28(1)：115–118.
[14] 鞠庆海，吴绵拨. 岩石材料三轴压缩动力特性的试验研究[J]. 岩土工程学报，1993，15(3)：73–80.(JU Qinghai，WU Mianba. Experimental studies of dynamic characteristic of rocks under triaxial compression[J]. Chinese Journal of Geotechnical Engineering，1993，15(3)：73–80.(in Chinese))
[15] ZHAO Y H，ZHAO J. Compressive strength of rock material at different strain rates[C]// Proceedings of the International Symposium on Strength Theories? Applications and Developments. Xi?an：[s. n.]，1998：75–429.
[16] 蔡美峰，何满潮，刘东燕. 岩石力学与工程[M]. 北京：科学出版社，2002：219–226.(CAI Meifeng，HE Manchao，LIU Dongyan. Rock mechanics and engineering[M]. Beijing：Science Press，2002：219–226.(in Chinese)) |
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2012, Vol. 31 
