摘要
为保障锦屏地下实验室(CJPL)硐室群的长期稳定性,开展2400m深埋大理岩蠕变特性的研究,在常规三轴压缩试验的基础上进行分级加载蠕变试验,系统分析了大理岩蠕变过程中的轴向与环向变形规律及不同围压(5MPa和64MPa)下大理岩蠕变特征差异,采用等时应力-应变曲线法确定了大理岩的长期强度,并基于分数阶导数改进了大理岩蠕变模型。研究表明:13,27MPa围压下,大理岩轴向应力应变曲线达到峰值应力后快速跌落,40,53,64MPa围压下,峰值应力附近的应变曲线呈现明显的平台段,表明CJPL深部大理岩变形行为随着围压的增加具有由脆性向延性转化的趋势;无论是低围压还是高围压,相比于低应力水平,高应力水平下大理岩更容易发生蠕变变形且环向蠕变现象更加显著,蠕变过程中的扩容现象也更加明显,试样破坏时64MPa围压条件下的体积蠕变变形为5MPa围压下的16.3倍;在蠕变加载过程中,大理岩变形模量均为先增加后减小。变形模量增加阶段,高围压下增加幅度较低围压小,64MPa围压下试样变形模量增加的幅值为1.8GPa,小于5MPa围压下的3.6GPa,表明试样受高围压作用已经部分压密。随着应力水平的增大,变形模量减小,高围压下减小幅度较低围压更大,围压64MPa下试样变形模量减小幅值为9.4GPa,约为峰值变形模量的22%,围压5MPa下试样减小幅值仅为1.8GPa,约为峰值变形模量的4%,表明高围压试样在破坏前裂纹的产生和扩展更为剧烈,岩石劣化程度更大;相同偏应力条件下,围压越大的试样蠕变速率越小,但破坏时变形更大且扩容现象显著,表明相同外荷载条件下,深部围岩赋存环境应力水平较高,变形难以收敛,易发生时效大变形破坏;围压为5,64MPa时,采用等时应力-应变曲线法确定大理岩长期强度分别为170,290MPa,为相应围压三轴压缩强度的82%,73%;基于分数阶导数,改进了大理岩黏弹塑性损伤蠕�
In order to ensure the long-term stability of Jinping Underground Laboratory (CJPL) caverns,the creep characteristics of 2 400 m deep-buried marble were studied.The multi-stage loading creep tests were conducted on the basis of convention triaxial compression tests to analyze the law of axial and circumferential deformation of marble during the creep process and the difference of creep characteristics of marble under different confining pressures (5 and 64 MPa).Then the long-term strength of marble was discussed by using the isochronous stress-strain curve method and a creep model based on fractional derivative was proposed to describe the process of creep deformation.The results show that under the confining pressures of 13 MPa and 27 MPa,the axial stress-strain curves of marble drop rapidly after reaching the peak stress and under confining pressures of 40,53 and 64 MPa,the strain curves near the peak stress show obvious plateau section,which indicates that the deformation behavior of deep marble in CJPL tends to change from brittleness to ductility with the increase of confining pressures.Compared with low stress level,the marble under high stress level is more prone to creep,the circumferential creep phenomenon is more significant and the dilatancy phenomenon during creep process is more obvious.The volume creep deformation of specimens under 64 MPa confining pressure is 16.3 times of that under 5 MPa confining pressure.During the creep loading process,the deformation modulus of marble increases first and then decreases.In the stage of increasing modulus of deformation,the increasing range under high confining pressure is smaller than that under low confining pressure.The increase of deformation modulus under 64 MPa confining pressure is 1.8 GPa,less than 3.6 GPa under 5 MPa confining pressure,which indicates that the specimen has been partially compacted under high confining pressure.With the increase of stress level,the modulus of deformation decreases and the decrease range under high confining pressure is
作者
许多
吴世勇
张茹
张泽天
周济芳
邓建辉
任利
吴斐
XU Duo;WU Shiyong;ZHANG Ru;ZHANG Zetian;ZHOU Jifang;DENG Jianhui;REN Li;WU Fei(College of Hydraulic and Hydroelectric Engineering,Sichuan University,Chengdu610065,China;Yalong River Hydropower Development Company,Ltd.,Chengdu610051,China;MOE Key Laboratory of Deep Earth Science and Engineering,Sichuan University,Chengdu610065,China;State Key Laboratory for the Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing400044,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2019年第5期1456-1464,共9页
Journal of China Coal Society
基金
国家重点研发计划资助项目(2016YFC0600702)
国家优秀青年科学基金资助项目(51622402)
四川省青年科技创新研究团队资助项目(2017TD0007)
关键词
深部
大理岩
蠕变
长期强度
分数阶导数
depth
marble
creep
long-term strength
fractional derivative
