考虑冻融影响的岩石动态损伤特征及能量耗散研究

Because of drilling and blasting excavation as the mainly methods in the process of engineering construction in cold regions, the coupling with freezing-thawing and dynamic loading have significant impact on rock engineering’s break, stability and geological disaster prevention and control. Baced on the study situation on lack of rock dynamic damage characteristics and energy disspiption under the conditions of freezing and thawing. This program focuses on dynamic damage characteristics of rock under the conditions of freezing thawing. And freezing-thawing cycles experiments and impact damage experiment of rocks will be conducted on freezing-thawing testing machine and Split Hopkinson Pressure Bars (SHPB) test system. The Nuclear Magnetic Resonance (NMR) technology is using to measure the rock microstructures, and the pores distribution situation and variation characteristics of microstructure will be obtained too. By the method of combining macro and microstructure, the dynamic damage characteristics and energy dissipation law of rocks under the conditions of freezing-thawing will be analysis. And the relationship between microscopic characteristic parameters and macro mechanical parameters, energy consumption will be built respectively. A number of factors such as porosity, T2 spectrum, energy dissipation, broken blocks of rock are will be used to analyse the energy change, and the energy dissipation mechanism during the rock dynamic damage process under the conditions of freezing and thawing cycles will be researched. In this research, rock damage evolution equation and energy equation of impact damage are given with considering the effect of freezing-thawing and dynamic loading. And it reveals the damage mechanism of rocks under the conditions of combined with freezing-thawing and dynamic loading. The research results will provides the theory basis for research on rock dynamic mechanics in cold regions.

在寒区矿山及岩土工程的爆破开挖中，冻融作用及冲击荷载将对岩体破碎、稳定性及地质灾害防治产生重要影响。针对目前缺乏对冻融影响下岩石动态损伤特性及能量耗散研究的现状，本项目围绕冻融影响下岩石的动态损伤特性这一研究主题，利用冻融试验机、核磁共振仪和SHPB试验系统开展冻融循环影响下的岩石内部裂纹扩展特征测试和冲击损伤实验，旨在探讨冻融作用对岩石冲击损伤力学参数、细观特征参量及能耗规律的影响。项目通过宏、细观相结合的方法，获得冻融影响下岩石的动态损伤特性和能量耗散规律，建立细观特征参量与宏观力学参数的关系，并通过孔隙率、核磁共振T2谱分布、能量耗散、破碎块度等因素分析冻融影响下岩石动态破坏过程的能量变化，研究冻融作用对岩石动态损伤能量耗散的影响机理，建立考虑冻融影响的岩石冲击损伤演化方程及能耗方程，从而揭示出冻融影响下的岩石动态破坏机理，研究结果可为寒区岩石动力学研究和冻融灾害防治提供理论基础。

在寒区矿山及岩土工程的爆破开挖中，冻融作用及冲击荷载将对岩体破碎、稳定性及地质灾害防治产生重要影响。本项目以冻融影响下岩石的动态损伤特性为研究对象，利用冻融试验机、核磁共振仪和SHPB试验系统开展了冻融循环影响下的岩石细观结构损伤特征测试和冲击荷载实验，获得了冻融作用下岩石细观结构劣化规律及动态力学参数，分析了考虑冻融影响的岩石动态损伤演化过程及能耗耗散规律，揭示冻融影响下的岩石动态破坏机理。主要取得了以下研究成果：.（1）开展了冻融循环影响下岩石动态损伤特性研究，建立了冻融因素与岩石动态力学参数之间的关系，获得了冻融砂岩在冲击载荷作用下的破坏特征。.（2）利用核磁共振测试技术，研究了冻融影响下岩石孔隙结构劣化规律及动态力学特性，分析了冻融条件下岩石孔隙结构演化过程和动态破坏特征，并构建了砂岩NMR参数与动态力学特性参数之间的关联性。.（3）开展了冻融影响的花岗岩动态劈裂拉伸试验，研究了冻融作用对砂岩拉伸强度和破坏模式的影响，揭示了冻融作用下砂岩动态拉伸的破坏机理。.（4）根据基于SHPB的岩石冲击荷载实验结果，分析了冻融作用下岩石的能量吸收特征规律，掌握了动静组合加载条件下冻融岩石的能量耗散变化规律，以及冲击荷载下冻融岩石压缩破坏过程的能量耗散特性；对冻融影响下岩石的动态损伤变量进行了分析，建立了干燥常温、饱水常温、干燥冻结、饱水冻结四种环境条件下岩石损伤变量与冻融次数的关系。.本项目已发表论文14篇，其中SCI论文9篇，EI论文1篇，申请国家发明专利2项。研究成果为寒区岩石动力学研究、寒区矿山工程建设和冻融灾害防治提供了理论基础。