渗流作用下岩石渐进损伤及蠕变行为的实验研究

Geological disaster induced by creep damage of rock under high stress and hydraulic head is very prominent in rock engineering such as mine and hydroelectric station dam. It is fundamental to study rock creep damage and instability characteristics under the mutual interaction of high ground stress and seepage pressure for disaster prediction. In view of this scientific problems，first of all, uniaxial compressive creep experiments on rock with different immersion time based on the acoustic emission monitoring are carried out, and the time-dependent damage law and the basic characteristics of buckling failure in rock are understood. Secondly, a series of triaxial compressive creep tests under different confining pressures and seepage conditions with acoustic emission monitoring have been performed to study the effect of seepage pressure on the long-term strength of rock. The creep damage evolution function of rock with variables of volumetric strain rate, AE signal etc. will be established based on the experiment data, and then the relationship of rock long-term strength with seepage pressure, stress and AE will be proposed. Accordingly the prediction formula of rock long-term strength will be established under the condition of fluid-solid coupling. Finally, the evaluation function of rock creep damage and the prediction formula of rock long-term strength are embedded in FLAC. And it will be applied to the site-specific Zhangmatun iron mine, to evaluate the long-term strength and stability of surrounding rock. Theoretical relationship about creep damage and long-term strength are modified and verified on site by tracking the subsequent seismic data of surrounding rock. This study provides theoretical and practical basis for research creep damage of deep surrounding rock under the condition of fluid-solid coupling.

在采矿、水电等岩石工程中，高应力、高水头渗流作用下由于围岩的蠕变损伤及失稳破裂诱发的地质灾害十分严重，研究流固耦合作用下岩石的蠕变损伤和失稳特征是进行灾害分析预测的理论基础。该项目首先开展不同浸水时间的岩石单轴压缩蠕变声发射监测实验，认识岩石损伤时效性规律及失稳破坏的基本特征；其次，进行不同渗透压力、围压等条件下的岩石蠕变损伤三轴实验，研究渗透压差对岩石长期强度影响的基本规律。基于流变、渗流等理论，以实验数据为基础，建立以体积应变率、AE信号等参数为变量的岩石蠕变损伤评价函数，并据此建立流固耦合条件下岩石长期强度的预测公式。最后，将蠕变损伤评价函数和岩石长期强度的预测公式嵌入到FLAC软件，并应用于张马屯铁矿的工程实践，对围岩的长期强度和稳定性进行评价，通过跟踪后续围岩微震数据，对提出的理论关系进行修正和现场验证。该研究对揭示流固耦合作用下深部岩体流变失稳机理提供理论和应用基础。

项目主要是围绕渗流条件岩石渐进损伤及流变行为机理开展研究，围绕着计划任务书制定的主要研究内容和关键科学问题，开展了不同浸水时间的岩石损伤图像表征，提出一种非饱和砂岩试件的含水均匀性表征方法，并讨论不同泡水时间对该砂岩单轴抗压强度的影响；基于所建立的蠕变损伤模型，通过数值模拟研究单轴和三轴压缩作用下绿砂岩蠕变损伤破坏过程。分析差应力对岩石蠕变应变和破坏时间的影响，再现蠕变过程中裂纹的萌生、扩展直至贯通的全过程。开展不同尺寸绿砂岩试样单轴压缩蠕变破坏数值模拟，分析长期强度的尺寸效应；利用Burgers体蠕变方程进行数值建模，建立了含水率与岩石蠕变参数之间的关系采用阻尼最小二乘法进行拟合和参数辨识，建立了考虑含水损伤效应的一维蠕变方程。相关的研究成果在济钢张马屯铁矿、招金集团夏甸金矿、小纪汗煤矿等相关矿山的深部岩体含水劣化机理研究及现场支护均提供了理论基础。