三轴循环加卸载条件下砂岩能量和孔隙演化  

Sandstone energy and pore evolution under triaxial cycle loading and unloading conditions

作　　者：刘腾龙 毕靖 王超林 党爽 沈明轩 LIU Tenglong;BI Jing;WANG Chaolin;DANG Shuang;SHEN Mingxuan(School of Civil Engineering,Guizhou University,Guiyang 550025,Guizhou,China)

机构地区：[1]贵州大学土木工程学院,贵州贵阳550025

出　　处：《水利水电技术（中英文）》2024年第3期184-195,共12页Water Resources and Hydropower Engineering

基　　金：国家自然科学基金(52164001)。

摘　　要：【目的】为了对考虑复杂应力环境下的岩土工程破坏特征演化及稳定性加固提供指导依据,【方法】对砂岩进行循环加卸载试验,基于宏观三轴压缩试验和微观核磁共振试验研究砂岩能量和孔隙演化规律。【结果】结果显示:砂岩在三轴循环加卸载下偏应力-应变曲线出现了明显的滞回环,试样峰值强度与围压成正相关关系,并且试件延性破坏程度随初始围压增加而增强;基于能量密度准则,径向能量表现出相似的变化规律,耗散能均在最后一个阶段明显增加,且径向总能量和径向弹性应变能差距变大;基于核磁共振理论,发现试件T_2谱和核磁成像灰度值变化规律一致。【结论】结果表明:从滞回环和能量密度准则揭示了岩石在试验过程中的能量损耗特征和岩石的破坏是因为岩石储存弹性应变能的能力达到极限导致能量的急剧释放;从微观核磁共振成像结合试件宏观破坏特征分析,两者在破坏形态上高度一致,增加初始围压可以提高试件循环次数从而致使试件峰值强度增大。[Objective]In order to provide guidance for the evolution of geotechnical engineering damage characteristics and stability reinforcement under the complex stress environment.[Methods]The cyclic addition and unloading test of the sandstone was conducted,and the sandstone energy and pore evolution law were studied based on the macroscopic triaxial compression test and the microscopic NMR test.[Results]The result show that the partial stress-strain curve,the peak strength and the circumference pressure are positively correlated,and the test failure increases with the increase of the initial circumference pressure.Based on the energy density criterion,the radial energy shows a similar variation pattern.The energy dissipation increases significantly in the last stage,and the gap between the radial total energy and the radial elastic strain energy of the T 2 spectrum of the specimen is larger.[Conclusion]The following conclusion are drawn:from the limit of the hysteresis ring and the energy density criterion,the energy loss characteristics of the rock and the destruction of the rock;from the microscopic nuclear magnetic resonance imaging combined with the analysis of the peak strength of the specimen.

关 键 词：偏应力-应变曲线 滞回环 能量密度 耗散比 核磁成像 T_(2)谱 破坏形式 影响因素 

分 类 号：TU458[建筑科学—岩土工程]