裂隙岩石注浆加固后的疲劳损伤机理研究

The mechanical properties of rock mass under cyclic loading is one of the important factors which influence the long-term stability of rock mass engineering. It is confirmed that study the fatigue deformation characteristics and the damage evolution law under cyclic loading will be helpful to recognize the failure mechanism correctly and evaluate the long-term stability scientifically. The cracked rock after grouting reinforcement was chosen as research object in this proposal. The fatigue failure mechanism and damage evolution model of the grouting reinforced rock will be studied as a basic scientific research. The static strength and deformation variation of the grouting reinforced rock will be studied by static compress test and the static failure mechanism will be revealed and the influencing factors of the damage will be analyzed. The influence factors and influence law of the fatigue damage will be investigated by irreversible deformation variation. Compared with the static failure mechanism of the grouting reinforced rock and the fatigue failure mechanism of the original cracked rock, the fatigue failure mechanism of the grouting reinforced rock will be revealed. In virtue of the analysis of irreversible deformation with cyclic number, the fatigue deformation properties of the specimens will be discussed. The influence of the mechanical properties of factors to the fatigue damage cumulative quantity will be studied. The relationship between the residual plastic deformation, the residual strength, the remaining life and the cycle number can be built through unloading experiments. The residual plastic strain difference of the starting instant and the destroy moment of macroscopic damage will be adopted to define the damage variable. The damage evolution equation of the grouting reinforced rock under cyclic loads can be derived according to the defined damage variable. It can be used to predict the residual strength of the grouting reinforced rock under cyclic loading and provide theoretical and experimental evidence for the grouting reinforced of the mining, tunnel, slope and other geotechnical engineering..

岩体在周期荷载作用下的力学性能是影响岩体工程长期稳定性的重要因素之一，研究周期荷载作用下岩石的疲劳变形特性及损伤演化规律，有助于正确认识岩体的破坏机理，科学地评价岩体的长期稳定性。本项目以裂隙岩石注浆加固体为研究对象，对注浆加固体的疲劳破坏机理以及损伤演化规律进行基础科学研究。通过裂隙岩石注浆加固后的静动态加载实验，分析注浆加固体的强度与变形规律，揭示裂隙岩石注浆加固后的静态加载破坏机理。研究疲劳破坏过程中不可逆变形的变化规律，探讨疲劳损伤累积量的影响因素以及影响规律，对比静态破坏机理、原裂隙岩石疲劳破坏机理，揭示注浆加固后的疲劳破坏机理。观测残余塑性变形、剩余强度和寿命随循环次数的变化规律，建立循环次数与残余塑性应变之间的对应关系，利用残余应变差来定义损伤变量，推导损伤演化方程，对承受循环荷载作用的注浆加固岩体进行剩余寿命预测，为采矿、隧道、边坡等岩土工程注浆加固提供理论和实验依据。

注浆加固是地下工程结构事故处理与预防的主要手段，由于岩体工程的隐蔽性以及岩体内部裂隙、孔洞等缺陷分布的随机性，开展注浆加固后岩体的破坏机理研究，是一个具有挑战性的研究课题，关于周期荷载下的注浆加固体的力学性能及破坏机理研究尚无系统研究，其疲劳寿命及损伤演化模型尚未建立，本研究基于试验研究，以注浆加固后的岩石及类岩石材料为研究对象，通过抗弯及抗压静态加载和疲劳加载试验，揭示注浆加固后的破坏机理，并建立相应的疲劳寿命方程和损伤演化模型，本项目研究完成了: (1)探讨了树脂和水泥加固含裂隙红砂岩、大理岩、类岩石材料的压缩破坏机理，分析了注浆材料、裂纹类型、裂纹数量岩石类型等因素对应力重分布即开裂模式的影响规律；(2)揭示了树脂加固含裂隙岩石三点弯破坏机理，研究三种裂隙形式、注浆深度、增韧树脂对破坏模式的影响规律；(3)考虑应力比对疲劳寿命的影响，建立了压缩和三点弯疲劳双对数高频疲劳寿命方程，结果吻合较好，疲劳寿命存在应力水平的门槛值，当应力水平小于门槛值，不会发生疲劳破坏，当循环比n/Nf达到0.5时，裂隙面横向应变突然迅速增加达到了门槛值导致开裂，与试验中观测到的开裂现象一致。(4)应力水平是影响疲劳力学性能的主要因素，当应力水平较高时，试样的损伤破坏分为三个阶段，即，初始损伤加速阶段，裂纹稳定扩展阶段和裂纹不稳定加速扩展阶段。而当应力水平较低时，损伤破坏退化为二个阶段；(5)根据Logistic 模型，提出一种倒S型曲线模拟疲劳损伤演化曲线，实测数据与拟合曲线吻合较好。本项目的资助下，共发表论文9篇，申请专利2项，出国参加国际会议1次并作分组报告，培养硕士研究生2名，另外还有1名在读硕士研究生。本项目研究成果可为地下及其他岩土工程注浆加固后效果评价提供理论与试验依据，为岩土工程事故处理及设计方案提供基础数据，具有重要的科学意义和实用价值。