共查询到16条相似文献，搜索用时 125 毫秒
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采动诱发岩体移动破坏过程数值模拟研究 总被引：3，自引：3，他引：0
本文基于岩石介质的宏观非线性主要是由非均质性和各向异性造成的, 应用新的数值计算软件RFPA(2D), 对采动引起岩体失稳破坏的全过程进了数值模拟研究。 相似文献
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单轴压缩下岩石蠕变失稳破坏过程数值模拟 总被引：3，自引：0，他引：3
在岩石破裂过程分析（RFPA2D）系统的基础上,考虑岩石损伤过程的时间因素影响,引入岩石细观单元蠕变本构方程,建立了考虑流变效应的岩石破裂过程RFPA2D数值模型。应用该模型模拟了恒定荷载作用下岩石的蠕变破坏过程,得到了岩石蠕变破裂的3个典型阶段：初始蠕变阶段、稳定蠕变阶段和加速蠕变阶段,模拟结果同实验室试验所观察到的现象十分吻合。这表明考虑流变效应的RFPA2D数值模型适用于模拟岩石的蠕变破坏这一复杂的、非线性演化问题。此外,数值模拟还揭示了岩石的宏观蠕变破坏实质上是细观层次上单元损伤累计的结果,这些结论对岩石工程的长期稳定性研究具有重要的理论指导和实践意义。 相似文献
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单轴压缩下岩石材料尺寸效应的数值模拟 总被引：1，自引：0，他引：1
考虑到岩石材料的非均质性,应用岩石破裂过程分析系统RFPA2D,对端面有摩擦和无摩擦两种条件下同直径不同长度的岩样,进行了单轴压缩下的数值模拟研究,并对模拟结果寻求了试验验证。结果表明,岩石强度的长度效应是由于岩样端面摩擦效应所致,而并非根源于材料本身的非均质性。 相似文献
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基于大直径霍普金森压杆数值试验的非均匀介质动态破坏过程分析 总被引：2，自引：0，他引：2
基于细观损伤力学基础而开发的动态岩石破裂过程分析系统RFPA2D代替大直径SHPB试验技术对非均匀介质的动态破坏过程和动态性能进行数值模拟,分析了加载波形和介质的非均匀性对数值试样的动态性能,如应力-时间曲线、应变-时间曲线、应力-应变曲线和应变率-时间曲线的影响。分析表明,大直径SHPB弥散效应对试验结果的影响较大,选择合适的加载波形可以减小SHPB装置中应力波的弥散效应,得到较准确的试验结果,其中三角形波加载可以有效降低大直径SHPB动态测试中的应力波弥散,是岩石等非均匀材料SHPB动态测试的较理想加载波形;在相同加载条件下,岩石的非均匀性对波的弥散效应影响不大,但非均匀岩石的试验曲线比均匀岩石的曲线在波峰后都出现较大的振荡,这主要是由于不同均质度的岩石其单元具有不同的破坏分布造成的,不是波形弥散造成的。 相似文献
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基于数值模拟的采动影响下覆岩裂隙演化过程分析 总被引：1，自引：0，他引：1
陈峰 《中国地质灾害与防治学报》2014,(2):60-64
以平顶山东部矿区为工程背景,利用岩石真实破裂过程分析软件（RFPA2D）,模拟了采动影响下覆岩介质损伤的动态发展过程。数值模拟结果表明,采动裂隙的形成过程是一个复杂的演化过程,在加载初期覆岩介质损伤小,声发射现象不明显,应力和位移基本上无变化,无明显裂隙产生。随着加载步的增加,覆岩内部介质出现破裂,声发射次数、应力值和位移值不断增加,此时裂隙场处于孕育、不断积累并扩大阶段。当声发射次数、应力值、位移值都达到最大值时,裂隙经过萌生、扩展之后形成宏观裂隙,进而导致煤岩体由弹性状态转变为塑性状态,使覆岩大面积垮落。该数值模拟结果对平顶山东部矿区的开采具有巨大指导意义。 相似文献
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陶可友 《地质灾害与环境保护》2018,(1)
运用岩石破裂过程分析软件RFPA2D,通过设置不同尺寸、剪切速率,探究裂隙形成、声发射能量以及位移之间的关系。数值模拟结果表明非均质岩石剪切破坏过程裂纹的扩展贯穿模式及声发射能量的对应关系。结果表明:(1)岩石剪切破坏的尺寸效应显著,剪切速率影响较小。(2)大裂隙的生成伴随较强的声发射能量,引起Y方向位移波动明显。(3)岩石剪切破坏剪裂纹是由大量细小张裂隙发育演变而来,对破坏模式起主导作用。 相似文献
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岩石破裂滑动过程及其声发射数值模拟 总被引：3，自引：0，他引：3
运用岩石破裂与失稳过程分析RFPA2D系统, 对滑动形成过程进行了数值模拟研究。滑动岩体似为非均匀弹 -脆岩石材料, 模拟结果再现了滑动形成从变形到破坏直至失稳的全过程及其声发射规律。 相似文献
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Numerical Simulation of 3D Hydraulic Fracturing Based on an Improved Flow-Stress-Damage Model and a Parallel FEM Technique 总被引：4，自引：4，他引：0
L. C. Li C. A. Tang G. Li S. Y. Wang Z. Z. Liang Y. B. Zhang 《Rock Mechanics and Rock Engineering》2012,45(5):801-818
The failure mechanism of hydraulic fractures in heterogeneous geological materials is an important topic in mining and petroleum engineering. A three-dimensional (3D) finite element model that considers the coupled effects of seepage, damage, and the stress field is introduced. This model is based on a previously developed two-dimensional (2D) version of the model (RFPA2D-Rock Failure Process Analysis). The RFPA3D-Parallel model is developed using a parallel finite element method with a message-passing interface library. The constitutive law of this model considers strength and stiffness degradation, stress-dependent permeability for the pre-peak stage, and deformation-dependent permeability for the post-peak stage. Using this model, 3D modelling of progressive failure and associated fluid flow in rock are conducted and used to investigate the hydro-mechanical response of rock samples at laboratory scale. The responses investigated are the axial stress–axial strain together with permeability evolution and fracture patterns at various stages of loading. Then, the hydraulic fracturing process inside a rock specimen is numerically simulated. Three coupled processes are considered: (1) mechanical deformation of the solid medium induced by the fluid pressure acting on the fracture surfaces and the rock skeleton, (2) fluid flow within the fracture, and (3) propagation of the fracture. The numerically simulated results show that the fractures from a vertical wellbore propagate in the maximum principal stress direction without branching, turning, and twisting in the case of a large difference in the magnitude of the far-field stresses. Otherwise, the fracture initiates in a non-preferred direction and plane then turns and twists during propagation to become aligned with the preferred direction and plane. This pattern of fracturing is common when the rock formation contains multiple layers with different material properties. In addition, local heterogeneity of the rock matrix and macro-scale stress fluctuations due to the variability of material properties can cause the branching, turning, and twisting of fractures. 相似文献
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Damage and fracture propagation around underground excavations are important issues in rock engineering. The analysis of quasi-brittle materials can be performed using constitutive laws based upon damage mechanics. The finite element code RFPA2D (Rock Failure Process Analysis) based on damage mechanics was used to simulate a loading-type failure process around an underground excavation (model tunnel) in brittle rock. One of the features of RFPA2D is the capability of modeling heterogeneous materials. In the current model, the effect of the homogeneous index (m) of rock on the failure modes of a model tunnel in rock was studied. In addition, by recording the number of damaged elements and the associated amount of energy released, RFPA2D is able to simulate acoustic activities around circular openings in rock. The results of a numerical simulation of a model tunnel were in very good agreement with the experimental test using the acoustic emission technique. Finally, the influence of the lateral confining pressure on the failure mechanism of the rock around the model tunnel was also investigated by numerical simulations. 相似文献
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储层岩体中的天然结构面对水力压裂缝网改造具有重要的影响。本文采用真实破裂过程分析软件RFPA2D-Flow,在考虑岩体非均质性和岩体渗流-应力-损伤破裂特性的基础上,对不同尺度天然结构面影响的水力压裂裂缝扩展与演化行为进行了模拟分析和讨论,研究结果表明:（1）当水力裂缝遇天然非闭合裂隙时,在水力裂缝靠近非闭合裂隙区间形成拉张应力区,水力裂缝与区间非闭合裂隙间微元体累进性张拉破坏是导致水力裂缝与非闭合裂隙贯通的主要机制;（2）层理等优势结构对水力压裂裂缝扩展及缝网形态影响十分显著,当最大主应力方向与层理面走向小角度相交时,层理结构面对水力裂隙的扩展起主要作用,当最大主应力方向与层理面走向大角度相交时,最大主压应力与层理面共同对缝网扩展起主导作用,随着优势结构面的增多和差应力的增大,水力压裂形成的缝网范围和复杂性程度随之增大;（3）储层水力压裂是一种局部范围内的短暂动力扰动过程,尽管断层的存在可以极大地影响水力裂缝的扩展模式,增大水力裂隙扩展高度,但相比于储层埋深,水力压裂对断层封闭性的破坏范围和断层活动性的扰动程度十分有限。 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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Rock formations in Glutenite reservoirs typically display highly variable lithology and permeability, low and complex porosity, and significant heterogeneity. It is difficult to predict the pathway of hydraulic fractures in such rock formations. To capture the complex hydraulic fractures in rock masses, a numerical code called Rock Failure Process Analysis (RFPA2D) is introduced. Based on the characteristics of a typical Glutenite reservoir in China, a series of 2D numerical simulations on the hydraulic fractures in a small-scale model are conducted. The initiation, propagation and associated stress evolution of the hydraulic fracture during the failure process, which cannot be observed in experimental tests, are numerically simulated. Based on the numerical results, the hydraulic fracturing path and features are illustrated and discussed in detail. The influence of the confining stress ratio, gravel sizes (indicated by the diameter variation), and gravel volume content (VC) on the hydraulic fracturing pattern in a conglomerate specimen are numerically investigated, and the breakdown pressure is quantified as a function of these variables. Five hydraulic fracturing modes are identified: termination, deflection, branching (bifurcation), penetration, and attraction. The propagation trajectory of the primary hydraulic fractures is determined by the maximum and minimum stress ratios, although the fracturing path on local scales is clearly influenced by the presence of gravels in the conglomerate, particularly when the gravels are relatively large. As the stress ratio increases, the fractures typically penetrate through the gravels completely rather than propagating around the gravels, and the breakdown pressure decreases with increasing stress ratio. Furthermore, the breakdown pressure is affected by the size and volume content of the gravel in the conglomerate: as the gravel size and volume content increase, the breakdown pressure increases. 相似文献
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锦屏一级水电站左岸边坡地质结构复杂,岩体存在大量深部裂隙、低波速松弛岩体、煌斑岩脉X及f2、f5断层,严重影响边坡的稳定性。采用基于强度折减法的岩石破裂过程分析RFPA方法对边坡典型部位在开挖后以及其对应弱层置换工况下的破坏全过程进行计算和分析,计算结果表明,f5断层在进行置换加固处理后,边坡安全系数较未置换弱层前提高了0.403,说明在岩质边坡开挖和支护前优先进行深部软弱结构置换处理,可以大大提高工程结构的安全储备。同时,RFPA强度折减法不仅能直观再现边坡潜在滑裂面从萌生到扩展直至贯通导致边坡整体失稳的全过程,而且可以得出边坡安全系数。研究结果对于边坡工程实施前稳定性评价和施工工序具有一定的参考价值。 相似文献