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1.
通过在类岩石材料中预制特定裂隙的方法,来模拟含"十字形"交叉裂隙的岩体,并对其在单轴压缩情况下的力学特性与破坏模式进行了试验研究。研究表明:(1)交叉裂隙试件中,次裂隙倾角对主裂隙倾角为45°时试件的抗压强度与起裂应力的影响最大,而对主裂隙倾角为90°时的影响最小。(2)单裂隙试件的抗压强度与起裂应力小于完整试件。交叉裂隙试件相对于单裂隙试件而言,当主裂隙倾角为0°和45°时,其抗压强度与起裂应力减小;当主裂隙倾角为90°时,其抗压强度与起裂应力增大。(3)在单裂隙试件中,当裂隙倾角为0°、45°和90°时,试件分别发生拉剪复合型破坏、剪切破坏和张拉破坏;相对于单裂隙试件而言,交叉裂隙试件破坏时产生的裂纹相对较多,破坏模式大多为拉剪复合型破坏,同时,在破坏过程中交叉裂隙试件发生复合其他破坏模式或直接导致试件破坏的滑移。上述结果对岩体工程的开挖和建设具有一定的参考价值。  相似文献   

2.
应用真实破裂过程分析系统软件RFPA2D2.0-Flow,采用细观方法表达岩石材料非均匀特性,建立了渗流-应力-损伤耦合模型;模拟分析了裂隙岩体在具有不同角度、不同长度、天然裂隙中点与井孔之间不同间距的单一天然裂隙条件下的水压致裂过程;通过对模型内拉伸裂缝萌生及扩展的描述,得出了天然裂隙角度、长度、天然裂隙中点与井孔的间距对裂隙岩体内水力裂纹的扩展及与天然裂隙相交模式的影响趋势。模拟分析结果表明:天然裂隙角度对模型稳定性影响较小,但对裂纹扩展模式的影响较大;天然裂隙与井孔间距的减小使模型的失稳水压值随着裂隙角度的增加而逐渐增大,但最大值与间距未减小时基本相同;随着天然裂隙长度的增加,模型的承载能力逐渐减弱,且减弱的幅度逐渐增大。  相似文献   

3.
针对室内试验测试多裂隙发育膨胀土抗剪强度指标的困难,提出以室内试验与数值模拟相结合的研究方法;以不同产状单裂隙面膨胀土三轴试样在200kPa围压下的CD试验结果为样本,基于颗粒流原理,采用PFC3D软件进行仿真试验,获得了与三轴试验结果相一致的PFC3D球颗粒参数和裂隙参数;以此参数为基础,进行不同裂隙产状膨胀土的仿真试验,初步探寻了裂隙发育对广西宁明膨胀土的强度影响规律。研究发现:裂隙发育是膨胀土强度衰减的主要原因;裂隙的空间角度、不同裂隙的组合、裂隙发育程度均对膨胀土抗剪强度指标产生影响,且对黏聚力的影响较大;与无裂隙情况相比,裂隙率达14.06%时,C值降低71.2%。  相似文献   

4.
裂隙网络是岩体地下水的主要流动通道,而工程岩体中裂隙网络错综复杂,裂隙网络的几何特征和连通性对其渗透性有着重要影响.为了综合量化裂隙迹长、间距、倾角、开度对裂隙网络连通性和渗透性的影响,基于信息熵原理,提出了三维裂隙网络地质熵理论和连通性指标-熵尺度,对比熵尺度与其他传统三维裂隙网络连通性指标,验证了熵尺度评价三维裂隙网络连通性和渗透性的合理性.结合锦屏一级水电站左岸边坡裂隙统计分布,建立三维裂隙网络渗流数值计算方法,分析不同裂隙迹长、倾角、间距、开度条件下三维裂隙面密度、无量纲逾渗密度、熵尺度和渗透系数的变化关系.结果表明:当体积率一定,考虑开度影响时,三维裂隙面密度和无量纲逾渗密度无法定量表征迹长和间距对裂隙网络连通性的影响;裂隙迹长与熵尺度和渗透系数呈负相关关系,裂隙间距和开度与熵尺度和渗透系数呈正相关关系,裂隙倾角变化对熵尺度和渗透系数影响较小;熵尺度与渗透系数的非线性关系近似满足二次多项式.  相似文献   

5.
复杂岩体含有大量的裂隙,这些裂隙尺寸及其分布形式等对弹性波传播都有很大的影响.本文加工了含单个裂隙、双裂隙和三个裂隙的玄武岩岩样单元对其进行组合,进行了25kHz、 50kHz、 400kHz、 600kHz和1000kHz 等5种频率的声波测试.通过考虑垂直或平行波传播方向的裂隙长度,来探索裂隙分布形式和不同裂隙长度对弹性波传播的影响,研究玄武岩的频散效应和波的衰减.结果表明:裂隙方向与波传播方向夹角对弹性波传播有很大的影响.当裂隙方向与波传播方向垂直时,散射效应最大;而当裂隙方向与波传播方向平行时,影响最小.上述结果可为理论模型和数值分析提供依据.  相似文献   

6.
项彦勇 《力学学报》2002,10(2):204-209
探讨了裂隙岩体中非饱和地下水渗流与溶质运移的几种概念模型的构造及数值模拟问题 ,如裂隙网络模型、连续体模型、等效连续体模型、双孔隙度 (单渗透率 )模型、双渗透率模型、多组份连续体模型等。在裂隙岩体中 ,非饱和地下水的渗流可能只局限于岩体中的岩石组份、或裂隙网络 ,也可能在裂隙和岩石中同时发生 ;对前一种情形只需考虑单一连续体中的流动 ,而后一种情况则需要包括地下水在岩石和裂隙之间的交换。岩体中的裂隙网络往往是溶质运移的主要通道 ;但当溶质在裂隙与岩石之间的渗透和扩散是重要的运移机制时 ,就需要考虑岩石与裂隙界面处的溶质交换。为了模拟岩石与裂隙之间地下水和溶质的交换 ,就需要了解岩石与裂隙之间相互作用的模式和范围 ,使得这类问题的概念模型较单一连续体模型多了一层不确定性、其数值模拟也变得更为困难。因为在实际问题中不易、甚至根本不能判别非饱和渗流的实际形态 ,具体采用哪种模型主要取决于分析的目的和对现场数据的掌握程度。不论哪种模型都会受到模型及参数不确定性的影响 ,因此必须考虑与其他辅助模型的比较.  相似文献   

7.
根据等效岩体理论,并考虑闭合裂隙面摩擦效应,建立了含多组贯穿闭合裂隙岩体的数学模型,给出了岩体轴向应变、等效弹性模量与等效泊松比的表达式,系统地研究了岩块性质和裂隙参数对等效弹性模量与等效泊松比的影响。结果表明:岩块弹性模量对等效弹性模量与等效泊松比的影响随弹性模量增大而逐渐减弱,等效泊松比与岩块泊松比近似呈正比例关系;当裂隙角度小于50°时,裂隙几何参数对等效弹性模量影响较大,对等效泊松比影响较小,随着角度增大,影响逐渐减弱;岩体变形受裂隙组数影响较大,由于闭合裂隙面的摩擦效应及多组裂隙间的制约作用,含两组及三组裂隙时岩体变形较小,只含一组裂隙时岩体变形最大,无裂隙岩体变形几乎可以忽略。  相似文献   

8.
为研究拉伸荷载下分支裂隙对破坏模式的影响,保持主裂隙参数不变,改变分支裂隙倾角和长度,利用扩展有限元方法模拟了弯折裂隙的动态扩展,总结了分支裂隙参数变化对破坏模式的影响。利用ABAQUS中的轮廓积分计算了分支裂隙尖端应力强度因子,并根据最大周向应力准则计算起裂角。结果表明:拉伸荷载下分支裂隙出现三种破坏模式;分支裂隙倾角和长度均对破坏模式有一定的影响。I型应力强度因子与分支裂隙倾角关系曲线呈斜"S"型,相应II型应力强度因子曲线呈上凸型;由于分支裂隙存在非尖端破坏,利用裂隙尖端应力强度因子判断开裂应结合相应的破坏模式。  相似文献   

9.
沈闹  李小春  王磊 《力学学报》2023,55(3):744-754
砂岩储层中由流体注入导致的地震活动与砂岩断层(裂隙)的摩擦行为有关.为了揭示不同温度条件下含流体砂岩裂隙的摩擦特性,在温度范围为25°C~140°C和有效法向应力范围为4~12 MPa的试验条件下,本文分别对干燥、水饱和以及注CO2锯切砂岩裂隙进行了速度分级加载试验.试验结果表明:(1)对于干燥砂岩裂隙,增大有效法向应力和升高温度均能增大裂隙的初始摩擦系数,而改变有效法向应力对裂隙摩擦稳定性影响不明显,仅升高温度会略微降低其摩擦稳定性;(2)对于水饱和砂岩裂隙,裂隙的初始摩擦系数同样会随着有效法向应力的增大而增大,但会受到升温的弱化作用,而增大有效法向应力和升高温度均能降低裂隙的摩擦稳定性;(3)对于注CO2砂岩裂隙,裂隙的初始摩擦系数受有效法向应力和温度变化的影响与水饱和砂岩裂隙相反,但裂隙的摩擦稳定性仅会随着温度的升高而降低,受有效法向应力的影响不明显.因此,砂岩裂隙的摩擦特性受有效法向应力、温度和注入流体类型的共同影响.该试验结果对理解流体注入诱发地震有一定的指示作用.  相似文献   

10.
岩体的力学性能受赋存在其中的裂隙的影响较大。本文以实际岩体工程中的节理岩体为背景,通过按一定比例配制而成的石膏砂浆材料来制作类岩石试件,采用在类岩石试件中预埋金属条抽出的方法来模拟不同倾角的"丁"字形交叉裂隙,研究室内单轴压缩条件下,"丁"字形交叉裂隙试件的力学特性。研究发现:(1)主裂隙倾角对试件的峰值应力有决定性作用,次裂隙则在一定程度上影响试件的峰值应力;(2)相对于仅有主裂隙的情况,次裂隙的存在,增大试件的弹性模量,但却减小试件的峰值应变和起裂应力;(3)次裂隙对裂隙试件裂纹起裂位置及其扩展方向的影响可归为三类:次裂隙对裂隙试件的裂纹起裂位置及其扩展方向的影响较小;次裂隙使裂隙试件的翼裂纹沿着主(次)裂隙的一端及其次(主)裂隙的两端开始起裂及扩展;次裂隙的存在引起了主裂隙两端次生裂纹的产生。  相似文献   

11.
A weakly compressible SPH solver is presented for applications involving nonlinear interaction between water waves and floating bodies. A complete algorithm able to compute fully coupled viscous Fluid–Solid interactions is described. No slip boundary condition on the solid surface is enforced through a ghost–fluid technique and the global loads are evaluated through the momentum exchange between fluid and ghost particles. A dedicated algorithm is developed to manage the intersection between the free surface and the solid profile. An explicit synchronous algorithm is proposed for the full coupling between fluid and rigid bodies. Stability, convergence and conservation properties are tested on several freely floating test cases and a final validation of the full algorithm is performed for the interaction between a 2-D box and a wave packet.  相似文献   

12.
基于土拱效应的抗滑桩与护壁桩的桩间距分析   总被引:4,自引:0,他引:4  
抗滑桩与护壁桩分别在滑坡治理和基坑支护中发挥着巨大的作用 ,其实施正是利用了土中的成拱效应 ,然而传统桩的设计虽考虑土拱效应的存在 ,但桩间距确定理论与方法并未建立起来。本文首先基于土体的极限平衡条件对滑坡推力作用下的土体中的成拱作用进行研究 ,得出了抗滑桩的最大桩间距公式 ,并以某一具体工程为例 ,对该最大桩间距的物理意义和可用性进行了讨论。在此基础上 ,给出了在考虑土拱效应的情况下合理桩间距的确定方法 ,并以此为据 ,对边坡加固设计提出一些建议.  相似文献   

13.
The hydraulic diffusivity and permeability of a rock mass can be measured with a double packer permeameter, placed in a long bore hole. If the flow is steady, the relation between supply pressure and flux is a measure of the permeability whereas if the flow is transient, the relation is a measure of both the hydraulic diffusivity of the rock and the elasticity of the equipment. If the equipment is effectively rigid and the distance between the packers is much bigger than the size of the packers, an approximate closed solution is characterized bytwo parameters: the distance between the packers divided by the radius of the hole and the width of the packers divided by the radius of the hole. The flow is fully 3-D if the hydraulic diffusion distance far exceeds the distance between the packers. If the elasticity of the equipment is not negligible, the transient solution is characterized byone parameter including the elasticity coefficient of the equipment the conductivity of the rock and the radius of the hole. The relations between pressure and flux is given as a closed formula, suitable for engineering practice.  相似文献   

14.
15.
In this paper, an analytical method is used to investigate the Rayleigh wave generation in a stratified structure and the wave generation in a dry sandy layer constrained between the couple stress and inhomogeneous orthotropic half-spaces. This study is devoted to analyzing the impact of various effective parameters associated with the media on the phase velocities of the wave. The displacement components for each medium are derived by implementing the separable variable method. The frequency equation is secured by using the displacement components in the boundary conditions, imposed at the interfaces between the layer and half-spaces. Moreover, the secured equation is the relation between the phase velocity and the wave number. Numerical computations are performed, and graphical representations are demonstrated between the phase velocity and the wave number for both phase velocities with different values of the parameters.The comparison between the phase velocities is observed for the same value of each parameter.  相似文献   

16.
本文分析了环空状态下的工作钻柱与井壁的接触机理,建立了钻柱与井壁动态摩擦接触的一般模型,提出了解决待定边界问题及钻柱动态分析的计算方法。计算说明不同工况下,钻柱与井壁具有不同的接触形式。  相似文献   

17.
Magnetorheological elastomers (MRE) are particulate composite materials, whose fillers are structured by a magnetic field during curing. These particles are brought in quasi-contact by the field, in a chain-like unidirectional structure. Due to this organization the local stresses between the particles is high and debonding between particles and elastomer occur at low strain. We have experimentally studied and analytically modeled the progressive breaking of the polymer-to-particle bonds. The two cases of strong and weak bonds between elastomers and particles have been studied. The analytical model correctly reproduces the stress strain curve in the presence of a debonding process although overestimating the size of the debonding cavity which is obtained by comparison between experiments and FEM simulations. The extension of the model to a chain of spheres allows to well explain the Mullins effect on MRE. Furthermore it is shown that the quality of the bonds between the particles and the elastomer does not influence the change of stiffness brought by the application of a magnetic field.  相似文献   

18.
INTERACTIONOFTURBULENTCOHERENTSTRUCTURESANDSMALLSCALESTRUCTURESLiuShihe刘士和,LiangZaichao梁在潮(ReceivedSept.8.1991:Communicatedby...  相似文献   

19.
With the help of plant roots, slope vegetation makes the slope soil mass become a composite material of soil and roots, and thus enhances shear strength of the slope soil mass and stability of the slope. However, the related studies at present are still qualitative. In this paper, quantitative analysis of the interaction between roots and soil mass are made. By the analysis of the interaction between herbaceous plant roots including lateral roots of woody plants and rock and soil mass, a mechanical model of the interaction between frictional roots and soil is established, and its correctness is shown. A mechanical model of the interaction between anchorage root, namely, woody plant taproot, and soil is also established. The establishment of the models provides a useful means in quantitative analysis of the interaction between plant roots and soil, and has practical values.  相似文献   

20.
Stress magnification in thin ligaments between small and large cylindrical voids is obtained by matching the inner field approximation by beam theory to the outer rigid-body field in the bulk of the material. A void between two larger voids is modeled as a large hole within a strip of straight edges (boundaries of the holes with infinite radii of curvature). Both stretching and bending types of loading are applied to the strip. Comparison of different orders of stress magnification for different geometries and loading conditions is made. It is shown that the order of stress magnification in thin ligaments is (R/δ) n , where n=1/2 in the ligament between one small and one large void, n=1 in the ligament between one small void and two large voids, or between two small and two large voids, and n=2 in the ligament between a large void and a small void coalescing with another large void. The relevance of these results for the study of material failure by void growth and coalescence is discussed.  相似文献   

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