共查询到18条相似文献，搜索用时 656 毫秒
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数字图像技术在岩石细观力学研究中的应用 总被引：1，自引：0，他引：1
岩石内部的细观组成和结构决定了其在外力作用下的应力-应变状态,进而控制了其宏观力学响应和破坏机制。数字图像处理技术作为一种材料细观尺度上的空间结构精确测量和数字表述手段,已广泛应用于土、岩石及混凝土的细观结构定量分析中。应用数字图像处理进行的岩石细观力学研究是对岩石力学研究方法的革新。现阶段主要研究内容包括：岩石裂隙隙宽的非接触测量,数字表述岩石结构的非均匀性,进行岩石细观力学行为分析,将提取的岩石数字特征值与相应的岩石物性结合以实现岩石流-固耦合研究,建立基于数字图像技术的岩石细观力学数值模拟方法。在研究相关文献的基础上,对数字图像技术在岩石细观力学定量研究中的成果进行客观评述,探讨各种方法的优缺点,分析展望数字图像技术在岩石细观研究领域中的应用前景。 相似文献
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用三维梁-颗粒模型BPM3D(beam-particlemodelinthreedimensions)对岩石类非均质脆性材料的力学性质和破坏过程进行了数值模拟。梁-颗粒模型是在离散单元法基础上,结合有限单元法中的网格模型提出的用于模拟岩石类材料损伤破坏过程的数值模型。在模型中,材料在细观层次上被离散为颗粒单元集合体,相邻颗粒单元由有限单元法中的弹脆性梁单元联结。梁单元的力学性质均按韦伯(Weibull)分布随机赋值,以模拟岩石类材料力学参数的空间变异性。材料内部裂纹通过断开梁单元来模拟。通过自动生成的非均质材料模型对岩石类材料的破坏机理进行研究。岩石类非均质脆性材料在单轴压缩状态下破坏过程细观数值模拟结果显示,岩石材料宏观破坏是由于其内部细观裂纹产生、扩展、贯通的结果。通过数值模拟结果之间的对比分析,揭示出岩石试样宏观破坏模式随细观层次上韦伯分布参数的变化而不同。与实际矿柱破坏形态的对比分析表明了模型的适用性。根据数值模拟结果对岩石类非均质材料的破坏机理进行了探讨。 相似文献
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岩石细观结构对其变形强度影响的数值分析 总被引：1，自引：0，他引：1
利用数字图像处理技术表征岩石的非均匀性,并映射到有限元网格中,建立了能比较准确地反映岩石细观结构的数值模型。通过对花岗岩数字图像的处理,利用该模型进行花岗岩单轴压缩数值试验,研究花岗岩细观结构对其变形和强度的影响。研究表明,花岗岩细观结构对应力集中影响显著,在不同方向对花岗岩进行加载时,其抗压强度差异较大,表现出较强的各向异性行为,但对花岗岩弹性模量的影响很小。基于数字图像的数值分析方法为研究岩石细观力学性质提供了一种新的方法。 相似文献
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储层非均质性对水力压裂的影响 总被引：1，自引：0，他引：1
从岩石细观非均质性的特点出发,采用RFPA2D-Flow软件对单孔和双孔数值模型进行压裂计算,研究岩石非均质性对水力压裂的响应,重点探讨双孔模型孔间吸引效应对裂纹演化形态的影响。岩石细观单元的力学、水力学特性由统计分布生成以体现岩石的随机不均质性,水力压裂过程中流体压力传递通过单元渗流-损伤耦合迭代来实现。数值计算结果表明:(1)岩石非均质性影响裂缝的扩展形态,导致水力裂纹尖端微裂纹的分支。随着均质度的增加,水力裂纹的扩展形态变得更加平直光滑,单孔模型两侧裂纹更加对称,双孔间裂纹的连通性变差。(2)岩石的非均匀性对于岩石的起裂压力和地层破裂压力影响较大。随着均质度的增大,起裂应力和地层破裂应力增大,并且两者间的差值逐渐变小,在储层为均质的条件下,两者几乎相等。(3)相同的边界条件下,均质模型的应力分布曲线光滑连续,非均质模型的应力分布曲线呈现出明显波动,井眼对称剖面上的应力分布不尽相同,反映了细观单元强度非均匀性及裂缝扩展形态对应力分布的影响。(4)双孔模型孔间存在孔隙水压力增加带,孔间产生吸引效应,双孔方位影响临界压力。研究结果对水压裂试验设计和现场压裂施工具有一定的参考意义。 相似文献
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层状岩体的非均质性及各向异性导致其破裂方式及规律与均质岩体有显著不同。对层状岩体分别进行不同方式的单轴、双轴、三轴试验, 分析应力-应变曲线特征; 再利用ANSYS有限元软件进行数值模拟, 观察应力、应变在岩体上的分布, 通过曲线和图件的对比分析, 并结合岩石破裂理论, 总结不同应力状态下层状岩体的破裂方式、顺序及规律; 最后以富台地区为例, 对分析结果进行验证。研究结果表明, 不同受力方式对层状岩体破裂的影响体现在施加的载荷及约束与层面的方位。当应力方向与岩层面平行时, 强度大的石灰岩岩体发生集中应力, 首先破裂; 而应力与岩层面垂直时, 强度小的泥岩岩体首先破裂。岩石试验、数值模拟结果以及实例均成功验证了这个规律。 相似文献
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以有限差分法(FDM)为计算框架,利用Weibull分布描述细观单元弹性模量和单轴抗压强度的分布特征,采用弹塑性应变软化本构模型描述细观单元的力学响应,进而建立一种模拟非均匀岩石介质破裂的数值模型。采用该数值模型探讨了单轴压缩时细观均质度m及细观结构对数值试样宏观特性的影响。结果表明,（1）随着细观均质度提高,数值模型的非线性特征逐渐减弱,脆性逐渐增强;宏观峰值强度及弹性模量逐渐增大,峰值强度与lnm呈线性关系,而弹性模量与1/m为线性关系;数值试样表现出由塑性流动破坏至剪切破坏进而为张拉破坏的破坏模式;（2）当细观均质度一定时,细观结构或细观单元空间排列是决定岩石力学行为波动性的主要因素;应力–应变曲线峰前阶段对细观单元的空间排列不敏感,但峰值强度附近及峰后阶段对细观单元的空间排列比较敏感。 相似文献
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Digital Image Based Approach for Three-Dimensional Mechanical Analysis of Heterogeneous Rocks 总被引：2，自引：0，他引：2
Summary This paper presents a digital image based approach for three-dimensional (3-D) numerical simulation and failure analysis of
rocks by taking into account the actual 3-D heterogeneity. Digital image techniques are adopted to extract two-dimensional
(2-D) material heterogeneity from material surface images. The 2-D image mesostructures are further extrapolated to 3-D cuboid
mesostructures by assuming the material surface as a representation of the inner material heterogeneity within a very small
depth. The iterative milling and scanning system is set up to generate the 3-D rock mesostructures. A Hong Kong granite specimen
is used as an example to demonstrate the procedure of 3-D mesostructure establishment. The mechanical responses and failure
process under the conventional Brazilian tensile test condition are examined through numerical analyses. The stress distribution,
crack propagation process and failure model of heterogeneous material cases are simulated with a finite difference software.
The numerical results indicate that material heterogeneity plays an important role in determining the failure behavior of
rocks under external loading. 相似文献
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Natural damage such as fissures and pores make the rock microstructure show strong heterogeneity,which influences the failure process and mode. In this paper,the numerical test of freeze-thaw sandstone splitting failure with natural damage was carried out based on CT non-destructive identification technology,combined with digital image processing technology and CASRock numerical simulation software. The analysis of splitting failure mode,deformation localization and crack evolution process of freeze-thaw sandstone with natural damage reveals the failure mechanism of sandstone with natural damage under freeze-thaw and load. The results show that the expansion of primary pores（cracks）and the formation of new pores in sandstone are the main forms of freeze-thaw rock failure evolution. The failure of rock containing natural damage under freeze-thaw and load is related to the degree and distribution of natural damage. The generation of secondary cracks mostly occurs in natural damage-intensive areas. During the loading process,the stress in the localized damage zone is far greater than sandstone’s overall stress,and rock’s failure in the localized damage zone is synchronized with the energy release and stress release in the region. Localized damage reflects the evolution of cracks in rocks and helps to predict the direction of sandstone crack development. The failure mode of rock is related to the number of freeze-thaw cycles. The freeze-thaw cycles make the sandstone with natural damage gradually change from brittle failure to ductile failure,and the change of the overall strength of the rock is a gradual deterioration process. © 2022 Science Press (China). 相似文献
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细观非均匀性对脆性岩石材料宏观破坏形式的影响 总被引：6，自引：0，他引：6
岩石材料的宏观力学特征是材料内部细观力学特性的综合反映。对于脆性岩石材料,其内部的非均匀性对材料的宏观破坏形式有着重要的影响。应用演化细胞自动机方法（ECA）对岩石的非均匀性进行了初步的探讨。该方法以位移、力、应力和应变等矢量和张量作为系统的基本变量,定量计算了反映岩石破坏过程中应力集中以及应力重新分布的过程。在宏观上则认为脆性岩石材料是一种非均匀性材料,并假定脆性岩石材料的非均匀性符合Weibull分布,坡度参数m是Weibull分布中的反映分布非均匀程度的重要参数。通过对符合Weibull分布中不同坡度参数的脆性岩石材料进行数值模拟试验,发现由Weibull分布中的坡度参数表示的非均匀性是影响脆性岩石材料破坏方式的重要因素,材料的坡度参数越小,材料越不均匀,其破坏形式则越具有随机性;材料的坡度参数越大,材料越趋于均匀,其破坏形式越具有规则性,即趋于弹性材料的破坏形式,这与试验结果是吻合的。 相似文献
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基于图像检索技术的岩石单轴压缩破坏过程CT描述 总被引：1，自引：0，他引：1
基于X射线的CT扫描技术,因其具有多层位、对同一岩石试件可连续、无损扫描等优点,在岩石力学与工程研究中得到了广泛应用。对岩石单轴压缩破坏过程进行实时CT扫描,也是岩石力学研究的重要内容之一。针对三维显微CT试验系统实时监测煤岩单轴压缩破坏过程中,因位移误差会引起扫描层定位不准确,进而影响试验结果这一基本问题,提出了基于图像检索技术的CT扫描图像处理方法。通过对煤岩试样在单轴载荷作用下破坏过程的CT实时监测,并引入基于Manhattan距离的相似性计算方法,检索出岩石试件同一层位在不同应力状态下的相似扫描层。结果表明,采用图像检索的方法,可以有效地减小煤岩在加载破坏过程中位移误差的影响,更好地通过CT图像来描述煤岩在不同应力状态下的微裂纹分布状况和演化规律,从而在细观层次上揭示岩石在单轴压缩条件下破坏的基本规律。 相似文献
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A numerical analysis of rock creep-induced slide: a case study from Jiweishan Mountain,China 总被引：2，自引：1，他引：1
Tao Xu Qiang Xu Maolin Deng Tianhui Ma Tianhong Yang Chun-an Tang 《Environmental Earth Sciences》2014,72(6):2111-2128
Landslides and slope failures are very common phenomena in hilly regions, Southwestern China. These are hazardous because of the accompanying progressive movement of the slope-forming material. To minimize the landslide effects, slope failure analysis and stabilization require in-depth understanding of the process that governs the behavior of the slope. The present paper first briefly describes a three-dimensional numerical brittle creep model for rock. The model accounts for material heterogeneity, through a stochastic local failure stress field, and local material degradation using an exponential material softening law. Then a case study of the Jiweishan rockslide that occurred in China is numerically investigated considering the effect of the mining activity. Numerical simulations visualize the entire process of the Jiweishan rockslide from the fracture initiation, propagation and coalescence. The distribution and evolution of associated stress and deformation field during the slide are also presented. Numerical simulations show that the underground mining excavations have remarkably negative effect on the stability of the rock slope, which is one of the important triggering factors of the rockslide. Moreover, it is possible to take some precautions for the unstable failure of rock mass by monitoring acoustic emission (AE) events or microseismicities since the occurrence of clusters of AE events prior to the final unstable rockslide. The results are of general interest, because they can be applied to the investigation of time-dependent instability in rock masses, to the mitigation of associated rock hazards in rock engineering, and even to a better understanding of the seismic activities in geological and geophysical phenomena occurring in the earth’s crust. 相似文献
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利用相似材料模拟方法,借助数字散斑观测技术,对深埋隧道围岩岩爆倾向进行试验研究。分析考虑材料强度、开挖速度和支护作用影响下的岩爆发生和破坏规律,寻求岩爆发生与深埋隧道变形破坏之间内在的联系。试验结果与现场实际发生岩爆强度较高的岩石类型花岗岩、闪长岩等相比,破坏特征相似,且围岩强度越高,岩爆发生可能性越大;在高地应力状态和完整岩体中开挖速度对岩爆的发生影响较大;锚网支护对隧道围岩变形有一定的控制作用,也可一定程度上避免岩爆发生。支护试验结果与现场实际支护效果一致,随支护强度提高,隧道抵抗力增加,整体变形减小、稳定性提高。所得试验结论为深埋隧道的合理设计和安全开挖提供技术指导和理论依据,对革新深埋隧道开挖技术和支护技术具有重要的意义 相似文献
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The influence of the intermediate principal stress on rock strength has been studied comprehensively by previous researchers. However, the reason why rock strength firstly increases and subsequently decreases with the increase of intermediate principal stress is still unclear. In this paper, the mechanism of the intermediate principal stress effect on rock failure behaviour is revealed through a numerical method using the EPCA3D system (Elasto-Plastic Cellular Automaton). In this study, both homogeneous and heterogeneous rocks are considered. The heterogeneity of a rock specimen is modelled by introducing Weibull's statistical distribution. Two criteria, i.e. the Drucker–Prager and Mohr–Coulomb models, are used to determine whether a meso-scopic element in the rock specimen is in a failure state or not during the polyaxial stress loading process. The EPCA3D simulation reproduces the typical phenomenon of the intermediate principal stress effect that occurs in some rock experiments. By studying the EPCA3D simulated acoustic emission and complete stress–strain curves illustrating failure initiation, propagation and coalescence in the failure process of rocks, the essence of the intermediate principal stress effect is tracked. It is concluded that the heterogeneous stress distribution induced by the natural heterogeneity of rocks and the effect of the loading platen are two of the reasons producing the intermediate stress effect. Studies indicate that a moderate intermediate principal stress delays the onset of local failure, which in turn leads to an increase in the rock strength. However, once the intermediate principal stress reaches a certain value, local failure will be formed through the application of the intermediate principal stress. It is the number of failed elements in the pre-peak region that determines whether the rock strength decreases or not. The extent of rock strength reduction when the intermediate principal stress reaches a certain value is lessened with the increase in the minimum principal stress. 相似文献