水—力耦合条件下花岗岩裂隙力学和渗透性试验研究

发布时间：2018-01-30 02:09

本文关键词： 花岗岩三轴压缩试验张拉压剪裂隙渗透性微观力学结构　出处：《湖北工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：能源地下存储、CO_2地质封存、石油天然气和矿产的开采以及高放废物地下处置等众多与水相关的岩石工程是世界各国都十分关注的问题。在众多岩石中,由于花岗岩具有渗透性小、致密、强度高等一系列适合核废料、石油、天然气地下贮存的特点,国内外学者对花岗岩的力学行为进行了大量的研究。由于地下岩石工程的开挖与建造,形成了岩体开挖扰动区,在开挖扰动区的近场形成张拉裂隙而远场则形成压剪裂隙,以及地下水的存在,能源以及高放射性废物地下处置必须考虑以下诸渗流-应力过程的相互作用:1)由于地下岩石工程的开挖而引起的花岗岩区域碎裂过程以及由此而引起的岩体渗透率及裂隙张开度的变化;2)由于以上过程造成的地下水流场的变化,以及流场内压力对岩体应力、变形的反作用。由于完整花岗岩的渗透性极低,地下岩石工程的开挖扰动区多场耦合突出的特点:花岗岩裂隙中的多场耦合。由以上论述可见,建立真正能够从物理化学力学内在机制上准确反映开挖扰动区花岗岩裂隙渗流-应力耦合机理的理论模型和分析方法仍然是急需突破的首要课题和关键难题。事实上,开挖扰动区花岗岩裂隙渗流-应力耦合的宏观效应有其明确和深刻的细观机制,只有从细观角度出发,分析花岗岩张拉和压剪裂隙内渗流-应力耦合作用的不同机理,建立渗流-应力耦合条件下花岗岩裂隙细观-宏观的尺度关联机制,才有可能建立真正能够从物理化学力学机制上准确反映开挖扰动区花岗岩裂隙渗流-应力耦合机理的理论模型和分析方法。本文着重从细观角度对张拉和压剪裂隙内的渗流-应力耦合机理进行试验研究。论文主要研究工作和取得成果:1.开展了花岗岩常规三轴压缩试验。试验结果表明:花岗岩明显地具有脆性岩石的一些基本力学特征,如峰值强度对围压敏感性,破坏方式脆-延转化,体积变形压缩-膨胀转化。2.开展了对含张拉-压剪裂隙花岗岩渗透性试验。试验结果表明:1)随着静水压力的增加,所有试样的渗透率均迅速减小,然后趋于某个稳定值。这是由于裂隙的开度随静水压力增大而减小造成的;2)含张拉-压剪裂隙试样渗透率减小的速率,随着静水压力的增加而减小;3)随着静水压力的增加,含张拉裂隙试样的渗透率减小的速率大于含压剪裂隙试样的渗透率的减小速率。3.为了深入分析含张拉和压剪裂隙试样在静水压力加载条件下渗透率所表现出的不同演化规律,开展了含张拉-压剪裂隙面花岗岩细观扫描电镜试验。结果表明:单轴压缩试验所获得的花岗岩裂隙面比较光滑;并且随着围压的不断增大,裂隙面上明显地观察到逐渐增多的压剪型裂隙,裂隙面比较粗糙。因此,张拉和压剪裂隙面的不同细观结构决定了含张拉和压剪裂隙试样的不同渗透率演化规律。
[Abstract]:Many water-related rock projects, such as underground energy storage, geological storage, exploitation of petroleum, natural gas and mineral resources and underground disposal of high-level radioactive wastes, are of great concern to all countries in the world. Because of its small permeability, compact and high strength, granite is suitable for underground storage of nuclear waste, oil and natural gas. Scholars at home and abroad have done a lot of research on the mechanical behavior of granite. Because of the excavation and construction of underground rock engineering, rock mass excavation disturbance zone has been formed. The tension fracture is formed in the near field and the compressive shear crack is formed in the far field, and the groundwater exists in the near field. Energy and underground disposal of highly radioactive wastes must consider the following seepage stress processes: 1). The fracture process of granite region caused by excavation of underground rock engineering and the change of rock permeability and crack opening caused by it; 2) because of the change of groundwater flow field caused by the above process, and the reaction of pressure in the flow field to the stress and deformation of rock mass, the permeability of intact granite is very low. The characteristics of multi-field coupling in the excavation disturbance area of underground rock engineering are as follows: the multi-field coupling in the granite fissure, which can be seen from the above discussion. The establishment of a theoretical model and an analytical method that can accurately reflect the mechanism of seepage and stress coupling of granite fractures in the disturbed area of excavation from the intrinsic mechanism of physical and chemical mechanics is still a primary subject and a key problem in urgent need of breakthrough. Actually. The macroscopic effect of seepage and stress coupling of granite fissure in excavating disturbed area has its clear and profound meso-mechanism, but only from the view of meso. Different mechanisms of seepage and stress coupling in tensioning and compression shear fractures of granite are analyzed, and the meso-macro scale correlation mechanism of granite fractures under the condition of seepage stress coupling is established. It is possible to establish a theoretical model and an analytical method that can accurately reflect the mechanism of seepage and stress coupling of granite fractures in the disturbed area of granite excavation from the physicochemical mechanics mechanism. This paper focuses on the tension and compression shear fracturing from a meso point of view. The mechanism of percolation and stress coupling in the gap is studied experimentally. 1. The conventional triaxial compression test of granite has been carried out. The results show that the granite has some basic mechanical characteristics of brittle rock obviously. For example, the peak strength is sensitive to confining pressure, and the failure mode is brittleness and ductility transformation. Volume deformation compression-expansion transformation. 2. The permeability test of granite with tension-compression fracture is carried out. The results show that the permeability of all samples decreases rapidly with the increase of hydrostatic pressure. This is due to the decrease of crack opening with the increase of hydrostatic pressure. 2) the rate of permeability decrease with the increase of hydrostatic pressure; 3) with the increase of hydrostatic pressure. The rate of permeability decrease of tensile fracture specimen is greater than that of compressive shear fracture sample. 3. In order to analyze the permeability of tensile fracture specimen and compression shear fracture specimen under hydrostatic pressure loading, Of different evolutionary laws. The micro-SEM test of granite with tension-compression shear fissures is carried out. The results show that the granite fracture surface obtained by uniaxial compression test is quite smooth. And with the increasing of confining pressure, it is obvious that more and more compression-shear fractures are observed on the fracture surface, and the fracture surface is relatively rough. The different microstructures of tensile and compressive fracture surfaces determine the evolution of permeability of specimens with tensile and compressive shear fractures.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

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