摘要
针对深部岩体开挖过程中卸荷损伤与应力松弛耦合作用导致的时效性变形问题,以湖北巴东三叠系红层泥岩为研究对象,通过恒轴压卸围压试验模拟卸荷损伤,结合分级应力松弛试验揭示卸荷损伤-应力松弛次序作用下的泥岩宏细观力学及结构特征劣化规律。研究结果表明:随卸荷损伤程度(D_(0))增大,泥岩剩余应力比非线性下降23%~59%,快速松弛阶段主导作用增强,当卸荷损伤程度D_(0)≥28.80%时,应力跌落以快速松弛模式为主;基于SEM图像及数值软件计算细观分形维数表明卸荷损伤使孔隙分形维数提升10%~25%,应力松弛后进一步增加8%~15%,揭示了卸荷损伤与应力松弛的协同劣化机制。引入岩石损伤单元体,基于广义Maxwell模型构建了四元Maxwell体的卸荷损伤-松弛耦合本构模型,所建模型与传统模型相比拟合误差降低35%~52%,精确表征了卸荷损伤-松弛耦合效应。研究成果为深部岩体工程长期稳定性评估与支护设计阈值设定提供理论依据,弥补了传统流变理论忽略损伤累积的局限性。
In order to solve the problem of time-dependent deformation caused by the coupling of unloading damage and stress relaxation during the excavation of deep rock mass,the Triassic redbed mudstone in Badong,Hubei Province was taken as the research object in this study.The unloading damage was simulated by the constant axial pressure unloading confining pressure test,and the graded stress relaxation test was combined to reveal the deterioration law of the macro-fine mechanics and structural characteristics of the mudstone under the action of unloading damage-stress relaxation sequence.The results show that with the increase of the degree of unloading damage(D_(0)),the residual stress ratio of mudstone decreases nonlinearly by 23%~59%,and the dominant role in the rapid relaxation stage is enhanced,and the stress drop is dominated by the rapid relaxation mode when the degree of unloading damage is D_(0)≥28.80%.Based on the SEM images and numerical software,the mesofractal dimension calculated shows that the unloading damage increases the pore fractal dimension by 10%~25%,and further increases by 8%~15%after stress relaxation,revealing the synergistic deterioration mechanism of unloading damage and stress relaxation.The unloading damage-relaxation coupling constitutive model of quaternary Maxwell is constructed based on the generalized Maxwell model,and the fitting error of the model is reduced by 35%~52%compared with the traditional model,and the unloading damage-relaxation coupling effect is accurately characterized.The research results provide a theoretical basis for the long-term stability assessment and support design threshold setting of deep rock mass engineering,and make up for the limitations of the traditional rheological theory of ignorant damage accumulation.
作者
刘锋
朱星荧
曾刚
王宇
LIU Feng;ZHU Xing-ying;ZENG Gang;WANG Yu(Hubei Three Gorges Polytechnic,Yichang 443002,Hubei Province,China;Key Laboratory of Geological Hazards on Three Gorges Reservoir Area,Ministry of Education,Yichang 443002,Hubei Province,China)
出处
《中国农村水利水电》
北大核心
2026年第3期90-95,100,共7页
China Rural Water and Hydropower
关键词
泥岩
卸荷损伤
应力松弛
分形维数
本构模型
mudstone
unloading damage
stress relaxation
fractal dimension
constitutive model
