第36卷第12期 北京科技大学学报 Vol.36 No.12 2014年12月 Journal of University of Science and Technology Beijing Dec.2014 卸荷岩体细观损伤演化的核磁共振测试 胡振襄，周科平⑧，李杰林，高峰，王明球 中南大学资源与安全工程学院，长沙410083 ☒通信作者，E-mail:kpzhou(@vip.163.com 摘要为研究卸荷岩体内部孔隙结构的细观损伤演化特征，以大理岩为岩样，分别进行初始围压为10、20和30MP,不同卸 荷围压量的常规三轴卸荷试验和核磁共振测试实验，获得卸荷岩体的应力一应变曲线、横向弛豫时间T,分布、孔隙度及核磁共 振成像图像.随着卸荷围压比的增大，岩石由弹性变形转化为塑性变形，岩样内小孔隙的孔径增大，大孔隙的数量增多且孔径 增大：卸荷围压比低于90%，岩体损伤主要由孔隙数量的增多引起，卸荷围压比高于90%，损伤由孔隙数量和孔径均急剧增大 引起：岩样的孔隙度随着卸荷围压比的增大而增大，且增速越来越快：核磁共振图像直观地反映卸荷岩体内部孔隙数量、孔径 及结构变化情况. 关键词岩石力学：损伤：核磁共振：卸荷：孔隙度：围压比 分类号TU458 Meso-damage evolution of unloading rock mass based on nuclear magnetic resonance technology HU Zhen-xiang,ZHOU Ke-ping,LI Jie-lin,GAO Feng,WANG Ming-qiu School of Resource and Safety Engineering.Central South University,Changsha 410083.China Corresponding author,E-mail:kpzhou@vip.163.com ABSTRACT To investigate the meso-damage evolution characteristic of unloading rock mass,unloading confining pressure tests on marble specimens were first conducted under initial confining pressures of 10,20 and 30 MPa.Then nuclear magnetic resonance tests were performed on the unloaded specimens.The stress-strain curves,transverse relaxation time T,distribution,rock porosity,and nuclear magnetic resonance imaging pictures of the unloaded specimens were obtained.It is found that the deformation of the unloaded specimens changes from elastic to plastic with the increase of unloading confining pressure ratio.As the unloading confining pressure ratio increases,the size of small microcracks increases,and the number and size of large microcracks also increase.When the unloa- ding confining pressure ratio is less than 90%,the damage of rock mass is mainly caused by the increase in number of microcracks. But when the unloading confining pressure ratio exceeds 90%,the damage of rock mass is caused by the sharp increase in number and size of microcracks.The rock porosity increases with the increase of unloading confining pressure ratio,and the growth rate becomes greater.The development processes of the number,size and structure of microcracks in the rock specimens under different initial confi- ning pressures and different unloading confining pressure ratios can be directly visualized by nuclear magnetic resonance imaging pictures. KEY WORDS rock mechanics:damage:nuclear magnetic resonance:unloading:porosity:confining pressure 岩体是由多种矿物晶体、胶结物和节理、裂隙等 其内部裂隙产生、发展和贯通的过程.地下工程中 缺陷组成的非均匀体，岩体破坏的过程，其实质就是 由于开挖岩体的应力扰动和释放，产生次生应力场， 收稿日期：2014-06-17 基金项目：“十二五”国家科技支撑计划资助项目(2013BAB0205):国家自然科学基金资助项目(51274253)：中国博士后科学基金资助项目 (2013M542138) DOI:10.13374/j.issn1001-053x.2014.12.001:http://journals.ustb.edu.cn第 36 卷 第 12 期 2014 年 12 月 北京科技大学学报 Journal of University of Science and Technology Beijing Vol． 36 No． 12 Dec． 2014 卸荷岩体细观损伤演化的核磁共振测试 胡振襄，周科平，李杰林，高 峰，王明球 中南大学资源与安全工程学院，长沙 410083  通信作者，E-mail: kpzhou@ vip． 163． com 摘 要 为研究卸荷岩体内部孔隙结构的细观损伤演化特征，以大理岩为岩样，分别进行初始围压为 10、20 和 30 MPa，不同卸 荷围压量的常规三轴卸荷试验和核磁共振测试实验，获得卸荷岩体的应力--应变曲线、横向弛豫时间 T2分布、孔隙度及核磁共 振成像图像． 随着卸荷围压比的增大，岩石由弹性变形转化为塑性变形，岩样内小孔隙的孔径增大，大孔隙的数量增多且孔径 增大; 卸荷围压比低于 90% ，岩体损伤主要由孔隙数量的增多引起，卸荷围压比高于 90% ，损伤由孔隙数量和孔径均急剧增大 引起; 岩样的孔隙度随着卸荷围压比的增大而增大，且增速越来越快; 核磁共振图像直观地反映卸荷岩体内部孔隙数量、孔径 及结构变化情况． 关键词 岩石力学; 损伤; 核磁共振; 卸荷; 孔隙度; 围压比 分类号 TU458 Meso-damage evolution of unloading rock mass based on nuclear magnetic resonance technology HU Zhen-xiang，ZHOU Ke-ping ，LI Jie-lin，GAO Feng，WANG Ming-qiu School of Ｒesource and Safety Engineering，Central South University，Changsha 410083，China  Corresponding author，E-mail: kpzhou@ vip． 163． com ABSTＲACT To investigate the meso-damage evolution characteristic of unloading rock mass，unloading confining pressure tests on marble specimens were first conducted under initial confining pressures of 10，20 and 30 MPa． Then nuclear magnetic resonance tests were performed on the unloaded specimens． The stress-strain curves，transverse relaxation time T2 distribution，rock porosity，and nuclear magnetic resonance imaging pictures of the unloaded specimens were obtained． It is found that the deformation of the unloaded specimens changes from elastic to plastic with the increase of unloading confining pressure ratio． As the unloading confining pressure ratio increases，the size of small microcracks increases，and the number and size of large microcracks also increase． When the unloa￾ding confining pressure ratio is less than 90% ，the damage of rock mass is mainly caused by the increase in number of microcracks． But when the unloading confining pressure ratio exceeds 90% ，the damage of rock mass is caused by the sharp increase in number and size of microcracks． The rock porosity increases with the increase of unloading confining pressure ratio，and the growth rate becomes greater． The development processes of the number，size and structure of microcracks in the rock specimens under different initial confi￾ning pressures and different unloading confining pressure ratios can be directly visualized by nuclear magnetic resonance imaging pictures． KEY WOＲDS rock mechanics; damage; nuclear magnetic resonance; unloading; porosity; confining pressure 收稿日期: 2014--06--17 基金项目: “十二五”国家科技支撑计划资助项目( 2013BAB02B05) ; 国家自然科学基金资助项目( 51274253) ; 中国博士后科学基金资助项目 ( 2013M542138) DOI: 10． 13374 /j． issn1001--053x． 2014． 12． 001; http: / /journals． ustb． edu． cn 岩体是由多种矿物晶体、胶结物和节理、裂隙等 缺陷组成的非均匀体，岩体破坏的过程，其实质就是 其内部裂隙产生、发展和贯通的过程． 地下工程中 由于开挖岩体的应力扰动和释放，产生次生应力场