冲击荷载作用下离子型稀土风化层花岗岩损伤规律研究

发布时间：2018-05-13 19:11

本文选题：核磁共振 + SHPB　；参考：《江西理工大学》2016年硕士论文

【摘要】：本文主要研究冲击荷载作用下离子型稀土风化层花岗岩损伤演化规律,课题源于国家自然科学青年基金项目(编号51404111)。论文主要采用室内试验与理论分析的研究手段,结合核磁共振技术与SHPB试验装置系统开展了以下工作:(1)对试样进行了单轴抗压强度试验、超声波波速测试试验、NMR孔隙试验,分析了岩石波速与天然孔隙之间的关系、静荷载作用下的应力-应变曲线特征以及单轴抗压强度与波速的关系。(2)基于核磁共振技术,对离子型稀土矿山风化层花岗岩孔隙结构进行了测量,得出原始岩样的核磁共振2T分布、谱面积分布特征、孔隙度以及核磁共振成像等信息,结果显示天然岩样的2T分布包含5个波峰,内部孔隙结构分布主要以微小尺寸孔隙为主。(3)对不同初始孔隙度的岩石进行了冲击破坏实验,与静荷载相比动荷载作用下应力应变曲线没有压密过程的下凹段;岩石在冲击荷载作用下破坏模式多样,如压剪破坏、拉应力破坏等,其破碎程度并不取决于试样所吸收的绝对能量,而是与所吸收能量占临界破坏能的比值相关联。(4)结合核磁共振技术与SHPB试验装置系统对离子型稀土风化层花岗岩在应力波作用下的损伤演化规律进行了研究,得到了冲击前后岩石的2T谱分布、孔隙度、2T谱面积、核磁共振成像的变化特征与岩石内部孔隙结构分布的变化。结果表明岩石在动荷载作用下的孔隙度增加主要来源于孔隙的扩张、贯通以及新生孔隙,各个类型尺寸孔隙在循环冲击下其分布将越趋于均匀化,表明岩石内部的损伤是具有一定方向性的。(5)采用核磁共振成像技术,对经历SHPB杆冲击后的同一块岩样进行成像分析,获得了冲击前后的岩石的孔隙结构分布图,直观的展示了岩石内部结构在冲击前后变化特征,将冲击荷载下岩石内部微观结构的损伤演化规律进行了可视化。
[Abstract]:This paper mainly studies the damage and evolution law of granite in the ion type rare earth weathering layer under impact load. The project is derived from the National Natural Science Youth Fund Project (No. 51404111). The paper mainly adopts the research means of indoor test and theoretical analysis, and carries out the following work in combination with the nuclear magnetic resonance technology and the SHPB test device system: (1) the test The samples were tested by uniaxial compression strength test, ultrasonic wave velocity test and NMR pore test. The relationship between rock wave velocity and natural pores, the stress-strain curves under static load and the relationship between uniaxial compression strength and wave velocity. (2) on the basis of nuclear magnetic resonance technology, the pores in the weathered layer of the ion type rare earth mine are porous. The structure is measured and the NMR 2T distribution, spectral area distribution, porosity and magnetic resonance imaging of the original rock samples are obtained. The results show that the 2T distribution of the natural rock samples contains 5 peaks, and the distribution of the internal pore structure is mainly small size pores. (3) the rock of different initial porosity is impacted and destroyed. The stress strain curve under the action of dynamic load does not have the lower concave section of the compaction process compared with the static load; the failure modes of rock under the impact load are varied, such as the shear failure, the tensile stress damage and so on. The degree of breakage does not depend on the absolute energy absorbed by the specimen, but is related to the ratio of the absorbed energy to the critical failure energy. (4) Combined with nuclear magnetic resonance and SHPB test system, the damage evolution law of the ionic rare-earth weathered granite under stress wave is studied. The distribution of 2T spectrum, porosity, 2T spectrum area, the change characteristics of nuclear magnetic resonance imaging and the distribution of pore structure in rock and rock are obtained before and after the impact. The increase of porosity of stone under dynamic load mainly comes from the expansion of pores, through through and new pores. The distribution of each type of pore size will tend to homogenization under cyclic impact, which indicates that the damage in the rock is of certain direction. (5) the same block after the impact of SHPB rod is used by the technique of nuclear magnetic resonance imaging. The formation of rock pore structure before and after the impact is obtained by imaging analysis of rock samples, and the changes of the internal structure of rock before and after the impact are visually displayed, and the damage evolution law of the internal microstructure of rock under the impact load is visualized.

【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD315

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