胶结充填体蠕变特性及时效破裂演化机理研究

The destruction of backfill and instability process has obvious time effect, and the creep characteristic is a major cause of this phenomenon. In order to solve this problem, the methods such as theoretical analysis, laboratory test and numerical simulation are used to conduct the research on creep characteristic and time-dependent fracture evolution mechanism of cemented filling body. The research of backfill creep micro-seismic monitoring test is developed to analysis the micro-seismic characteristics at different creep stages of backfill. Combining the technique of scanning electron microscopy, the correspondence between micro-crack evolution and micro-seismic characteristic parameters is revealed. The characterization method of backfill micro-cracks evolution based on the micro-seismic characteristic parameters is proposed to construct the model of backfill creep micro-cracks evolution based on micro-seismic characteristic parameters. The damage theory and fracture mechanics theory are used to deduce the criterion of micro-crack damage evolution and construct the creep damage constitutive equations and fracture criterion on microscopic unit of backfill. The macro-microscopic numerical model of backfill creep damage and failure process is constructed by particle flow theory and PFC program. A numerical method which should be verified is proposed to characterize backfill creep characteristic and the whole process of time-dependent fracture evolution. To sum up, the research results can provide a theoretical basis for the research of cemented filling body stability and prevention of the geological disasters with "time lag".

充填体的破坏与失稳过程具有明显的时间效应，其蠕变特性是导致这种现象出现的一个主要原因。针对这一问题，本项目拟采用理论分析、室内试验和数值模拟相结合的方法，对胶结充填体蠕变特性及时效破裂演化机理进行研究。利用微震监测技术，开展充填体蠕变微震监测试验研究，分析充填体蠕变不同阶段微震特征；结合扫描电镜技术，揭示微裂纹演化与微震特征参数的对应关系，提出基于微震特征参数的充填体微裂纹演化表征方法，构建基于微震特征参数的充填体蠕变微裂纹演化模型；运用损伤力学和断裂力学理论，推导微裂纹损伤演化准则，构建充填体细观单元蠕变损伤本构方程及破裂准则；通过颗粒流理论与PFC程序，构建充填体蠕变损伤及破裂过程的宏-细观数值模型，提出一种能够表征充填体蠕变特性及时效破裂演化全过程的数值方法，并进行验证。研究成果最终可为胶结充填体稳定性研究及“时滞性”地质灾害的防治提供理论依据。

充填体的破坏与失稳过程具有明显的时间效应，其蠕变特性是导致这种现象出现的一个主要原因。针对这一问题，本项目采用理论分析、室内试验和数值模拟相结合的方法进行研究，取得了以下研究成果：通过胶结充填体超声波波速测试试验，结合损伤力学理论，构建了基于超声波波速的胶结充填体损伤演化方程，探明了胶结充填体超声波波速损伤演化规律，揭示了胶结充填体裂纹扩展及汇集模式与贯穿机理；根据单轴压缩声发射定位试验，阐明了胶结充填体微裂纹空间定位及声发射参数时序特征，揭示了荷载作用下胶结充填体内部裂纹演化机理；针对胶结充填体的空隙压密非线性变形特征，提出了胶结充填体损伤本构模型，结合FLAC3D数值模拟软件进行了二次开发，获取了基于FLAC3D的胶结充填体损伤本构数值模型；根据单轴压缩、分级蠕变和声发射监测试验，获取了胶结充填体蠕变变形及振铃计数、能量和振幅等声发射特征参数，从宏细观角度探讨了不同应力水平下胶结充填体蠕变变形和破坏特征研究；考虑应力水平和损伤的影响，引入损伤变量、新的二次黏性元件和开关元件，构建了能表征不同应力水平胶结充填体蠕变的改进Burgers模型。研究结果可为胶结充填体稳定性分析提供理论依据。