含预制裂隙花岗岩变形破坏特征三轴试验与离散元数值分析

发布时间：2018-05-04 01:17

本文选题：预制裂隙 + 岩石力学性质　；参考：《华侨大学》2017年硕士论文

【摘要】：水利水电、铁路、地热开采、石油天然气等工程施工过程中会遇到复杂的工程介质——节理裂隙岩体。天然岩体内部不同尺度裂隙相互贯穿、纵横交错,极大地影响了岩体自身的力学特性,使得强度、弹模以及泊松比等基本力学参数产生差异,这些差异与岩体变形过程当中内部裂纹发育的变化规律相一致。本文以五类裂隙花岗岩试件在0、5、10 MPa围压条件下进行压缩试验,研究裂隙和围压对岩石的宏观力学性质及破坏模式的影响;最后,通过颗粒流PFC2D软件,采用自主编制的预制裂隙双轴压缩程序对花岗岩进行裂隙和不同围压条件下数值模拟。模拟得到的结果与室内试验结果对比,在验证数值模型可靠的基础上,获取试样受荷载过程中内部细观参量,为研究裂隙花岗岩宏观力学特性的细观机理提供条件。论文主要的研究成果如下:同等围压条件下,随着裂隙数目增多,花岗岩样峰值强度和弹性模量降低;同类型裂纹岩样,随着围压的增大,花岗岩岩样的峰值强度、弹性模量、峰值轴向应变和峰值环向应变增大;完整岩样应力达到峰值强度后应力迅速跌落,应力应变曲线峰值处呈现倒“V”型,含预制裂隙花岗岩样应力达到峰值强度后曲线呈现缓慢跌落;完整岩样在单轴压缩条件下呈现劈裂贯通破坏,单轴压缩条件下含裂隙岩样裂纹首先在裂隙内部尖端萌生再沿着轴向扩展形成劈裂贯通破坏,而三轴压缩条件下含裂隙岩样呈现拉剪混合式破坏。借助PFC2D数值模拟软件,分析单轴、三轴加载过程中裂纹扩展规律,并从细观机制上解释围压和裂隙对宏观力学参数影响。本次研究宏细观结合,互为补充印证。
[Abstract]:Water conservancy and hydropower, railway, geothermal exploitation, oil and gas engineering will encounter complex engineering mediums-jointed fractured rock mass. The fractures of different scales in natural rock mass run through each other and crisscross, which greatly affects the mechanical properties of rock mass itself, and makes the basic mechanical parameters such as strength, modulus of elasticity and Poisson's ratio different. These differences are consistent with the law of internal crack development during rock deformation. In this paper, five types of fractured granite specimens are tested under the confining pressure of 0 ~ 5 ~ 10 MPa to study the influence of fracture and confining pressure on the macroscopic mechanical properties and failure mode of rock. Finally, by means of PFC2D software of particle flow, The prefabricated fracture biaxial compression program is used to simulate the granite fracture and different confining pressure. The simulation results are compared with the results of laboratory tests. On the basis of verifying the reliability of the numerical model, the internal meso-parameters during the loading process of the specimens are obtained, which provides the conditions for the study of the meso-mechanism of the macroscopic mechanical properties of the fissured granite. The main research results are as follows: under the same confining pressure, the peak strength and elastic modulus of granite samples decrease with the increase of the number of fissures, the peak strength and elastic modulus of granite samples with the increase of confining pressure, the peak strength and elastic modulus of granite samples decrease with the increase of confining pressure. The peak axial strain and the peak circumferential strain increase, the stress of intact rock sample rapidly falls after reaching the peak strength, and the peak value of stress-strain curve shows the inverted "V" type. The curves of granite samples with prefabricated fractures show a slow drop after the stress reaches the peak strength, and the intact rock samples show splitting through failure under uniaxial compression. Under uniaxial compression conditions, cracks of fractured rock samples first germinate at the tip of fractures and then propagate along the axial direction to form splitting through failure, while under triaxial compression conditions, fracture rock samples show tensile and shear failure. By means of PFC2D numerical simulation software, the law of crack growth during uniaxial and triaxial loading is analyzed, and the influence of confining pressure and fracture on macroscopic mechanical parameters is explained from the mesoscopic mechanism. This study combines macro-and-meso-view and is complementary to each other.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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