共查询到20条相似文献，搜索用时 31 毫秒
1.
The role of hydromechanical coupling in fractured rock engineering 总被引：19，自引：2，他引：17
This paper provides a review of hydromechanical (HM) couplings in fractured rock, with special emphasis on HM interactions
as a result of, or directly connected with human activities. In the early 1960s, the coupling between hydraulic and mechanical
processes in fractured rock started to receive wide attention. A series of events including dam failures, landslides, and
injection-induced earthquakes were believed to result from HM interaction. Moreover, the advent of the computer technology
in the 1970s made possible the integration of nonlinear processes such as stress–permeability coupling and rock mass failure
into coupled HM analysis. Coupled HM analysis is currently being applied to many geological engineering practices. One key
parameter in such analyses is a good estimate of the relationship between stress and permeability. Based on available laboratory
and field data, it was found that the permeability of fractured rock masses tends to be most sensitive to stress changes at
shallow depth (low stress) and in areas of low in-situ permeability. In highly permeable, fractured rock sections, fluid flow
may take place in clusters of connected fractures which are locked open as a result of previous shear dislocation or partial
cementation of hard mineral filling. Such locked-open fractures tend to be relatively insensitive to stress and may therefore
be conductive at great depths. Because of the great variability of HM properties in fractured rock, and the difficulties in
using laboratory data for deriving in-situ material properties, the HM properties of fractured rock masses are best characterized
in situ.
Electronic Publication 相似文献
2.
裂隙岩体流固耦合问题是目前国内外研究热点之一,采用离散元软件UDEC对裂隙岩体发生节理剪胀的渗透性变化规律进行了模拟分析。基于现场调查的裂隙信息统计生成裂隙网络岩体模型。 通过固定垂直应力、不断增加应力比RS(RS=水平应力/垂直应力)使岩体出现剪胀,采用库伦滑移节理模式对岩体在剪胀过程中的渗透性变化情况进行模拟。结果发现:当应力比较小(RS3.1)时,节理水力隙宽、流速、渗透系数等参数都随着应力比的增加表现出明显的降低; 而当岩体出现剪胀现象之后(应力比大于3.1),发生剪切滑移和剪胀现象的节理控制着裂隙岩体的总体渗流行为,与不考虑节理剪胀的计算结果相比,岩体渗透能力出现了显著增长。这一结果表明,剪胀对裂隙岩体渗透性的影响是显著而不可忽视的。 相似文献
3.
岩石裂隙的非饱和渗透特性是岩土、能源和环境等领域科学研究中的热点问题。采用三维激光扫描获取花岗岩裂隙的表面形貌特征,分析裂隙微观形貌特征对非饱和渗透特性的影响。研究在张拉、压缩、剪切等复杂荷载作用下裂隙开度分布的演化规律,建立复杂荷载作用下岩石裂隙非饱和毛细压力曲线演化模型。基于裂隙的微观形貌特征推导了岩石裂隙非饱和相对渗透系数模型,通过与试验数据对比,验证了模型的准确性和有效性,并在此基础上建立了复杂荷载作用下岩石裂隙非饱和相对渗透系数演化模型。研究成果对非饱和条件下裂隙岩体的水-力耦合机制研究具有一定指导意义。 相似文献
4.
开展贯通裂隙岩样在法向卸荷下的压剪破坏研究,有助于更好地理解岩体裂隙在卸荷条件下的失稳特征。对单裂隙贯通岩样开展剪切应力峰前一系列法向卸荷破坏试验,分析了法向卸荷下试样裂隙的变形及能量演化规律。结果表明,法向卸荷下裂隙压剪失稳时的法向应力大于常规直剪试验的对应值,裂隙的抗剪能力减弱;剪切位移随法向应力减小而增大;卸荷变形比K随裂隙轮廓面积比Rs的增加而增大;卸荷过程中总变形能U0由减小转变为增加的现象可用于预测岩石裂隙卸荷失稳。研究结果对理解贯通裂隙岩体压剪卸荷失稳破坏具有一定参考意义。 相似文献
5.
6.
裂隙的剪胀特性及扩展演化规律对岩体的渗流特性具有重要影响。为揭示裂隙剪胀及扩展演化对岩体渗流的影响,基于残余强度提出了一种能较好描述岩石硬化-软化特性的全剪切本构关系;结合剪切变形与裂隙开度的关系,利用最小势能原理和立方定律,建立了压剪作用下考虑裂隙剪胀特性的渗流应力耦合模型;假定压剪作用下裂隙发生Ⅰ型扩展,提出了伴有翼型裂纹的渗流模型,该模型不仅考虑了岩石的剪胀特性,更反映了裂隙扩展过程渗流的演化规律。对不同裂隙粗糙度的剪切应力-位移曲线进行分析,全剪切本构模型表现出较高的拟合精度。在剪切应力-位移关系基础上,通过剪切渗流试验数据对压剪作用下渗流模型进行验证,结果表明,该模型能较好地描述岩体剪胀阶段渗透性演化规律。利用等效裂隙简化裂隙网络,并通过试验数据进行验证,证实了裂隙扩展过程渗流-应力耦合模型的准确性与适用性。 相似文献
7.
8.
Qinghua Lei Xiaoguang Wang Jiansheng Xiang John-Paul Latham 《Hydrogeology Journal》2017,25(8):2251-2262
A study about the influence of polyaxial (true-triaxial) stresses on the permeability of a three-dimensional (3D) fractured rock layer is presented. The 3D fracture system is constructed by extruding a two-dimensional (2D) outcrop pattern of a limestone bed that exhibits a ladder structure consisting of a “through-going” joint set abutted by later-stage short fractures. Geomechanical behaviour of the 3D fractured rock in response to in-situ stresses is modelled by the finite-discrete element method, which can capture the deformation of matrix blocks, variation of stress fields, reactivation of pre-existing rough fractures and propagation of new cracks. A series of numerical simulations is designed to load the fractured rock using various polyaxial in-situ stresses and the stress-dependent flow properties are further calculated. The fractured layer tends to exhibit stronger flow localisation and higher equivalent permeability as the far-field stress ratio is increased and the stress field is rotated such that fractures are preferentially oriented for shearing. The shear dilation of pre-existing fractures has dominant effects on flow localisation in the system, while the propagation of new fractures has minor impacts. The role of the overburden stress suggests that the conventional 2D analysis that neglects the effect of the out-of-plane stress (perpendicular to the bedding interface) may provide indicative approximations but not fully capture the polyaxial stress-dependent fracture network behaviour. The results of this study have important implications for understanding the heterogeneous flow of geological fluids (e.g. groundwater, petroleum) in subsurface and upscaling permeability for large-scale assessments. 相似文献
9.
Coupled hydro-mechanical (HM) processes are significant in geological engineering such as oil and gas extraction, geothermal energy, nuclear waste disposal and for the safety assessment of dam foundations and rock slopes, where the geological media usually consist of fractured rock masses. In this study, we developed a model for the analysis of coupled hydro-mechanical processes in porous rock containing dominant fractures, by using the numerical manifold method (NMM). In the current model, the fractures are regarded as different material domains from surrounding rock, i.e., finite-thickness fracture zones as porous media. Compared with the rock matrix, these fractured porous media are characterized with nonlinear behavior of hydraulic and mechanical properties, involving not only direct (poroelastic) coupling but also indirect (property change) coupling. By combining the potential energy associated with mechanical responses, fluid flow and solid–fluid interactions, a new formulation for direct HM coupling in porous media is established. For indirect coupling associated with fracture opening/closure, we developed a new approach implicitly considering the nonlinear properties by directly assembling the corresponding strain energy. Compared with traditional methods with approximation of the nonlinear constitutive equations, this new formulation achieves a more accurate representation of the nonlinear behavior. We implemented the new model for coupled HM analysis in NMM, which has fixed mathematical grid and accurate integration, and developed a new computer code. We tested the code for direct coupling on two classical poroelastic problems with coarse mesh and compared the results with the analytical solutions, achieving excellent agreement, respectively. Finally, we tested for indirect coupling on models with a single dominant fracture and obtained reasonable results. The current poroelastic NNM model with a continuous finite-thickness fracture zone will be further developed considering thin fractures in a discontinuous approach for a comprehensive model for HM analysis in fractured porous rock masses. 相似文献
10.
裂隙岩体渗流-应力耦合等效渗流阻模型 总被引：2，自引：0，他引：2
针对含区域主干裂隙岩体在应力作用下的渗透特性进行了研究。运用单裂隙平行板渗流理论、弹性力学方法,结合模拟电路知识,提出等效渗流阻的概念。在分析裂隙岩体区域中主干裂隙系统几何构造的基础上,建立了基于等效渗流阻的- 渗流-应力耦合模型,得到了裂隙岩体等效渗流阻、渗透率与应力之间的关系,从而为研究含区域主干裂隙岩体的应力-渗流耦合规律提供了方便。结合一个基于等效渗流阻模型的算例,考察了含“人”字形组合裂隙试样的渗透特性。经进一步细化后,该模型可用于分析地应力作用下的含区域主干裂隙岩体渗流演化规律。 相似文献
11.
Capturing the two‐way hydromechanical coupling effect on fluid‐driven fracture in a dual‐graph lattice beam model 
下载免费PDF全文
下载免费PDF全文 Fluid‐driven fractures of brittle rock is simulated via a dual‐graph lattice model. The new discrete hydromechanical model incorporates a two‐way coupling mechanism between the discrete element model and the flow network. By adopting an operator‐split algorithm, the coupling model is able to replicate the transient poroelasticity coupling mechanism and the resultant Mandel‐Cryer hydromechanical coupling effect in a discrete mechanics framework. As crack propagation, coalescence and branching are all path‐dependent and irreversible processes, capturing this transient coupling effect is important for capturing the essence of the fluid‐driven fracture in simulations. Injection simulations indicate that the onset and propagation of fractures is highly sensitive to the ratio between the injection rate and the effective permeability. Furthermore, we show that in a permeable rock, the borehole breakdown pressure, the pressure at which fractures start to grow from the borehole, depends on both the given ratio between injection rate and permeability and the Biot coefficient. 相似文献
12.
岩溶化裂隙岩体是普遍发育于自然界中具有初始损伤的岩体。为了研究岩溶化裂隙岩体损伤破坏特征,本文以贵州某地赋存的溶蚀岩体为研究对象,运用损伤力学理论构建岩溶化裂隙岩体在单轴压缩条件下的损伤演化模型,并建立岩溶化裂隙岩体损伤演化方程。采用颗粒流数值软件进行单轴压缩数值试验,进一步研究岩溶化裂隙岩体试件在单轴压缩条件下的损伤演化特征,分析岩溶化裂隙岩体的微观损伤特征。结果表明:岩溶化裂隙岩体的初始损伤主要包括溶蚀损伤和裂隙损伤。岩溶化裂隙岩体的初始损伤随着溶蚀率的增加而增加,最终增加速率趋于平缓;岩溶化裂隙岩体的损伤演化曲线均呈“S”型变化,先缓慢增加,再迅速增加,最后缓慢增加至损伤值1;岩溶化裂隙岩体存在异构特征,导致破坏裂隙起源于具有初始损伤的溶蚀孔洞和裂隙处,随后裂隙经历萌发、扩张和剪切作用、数量和长度增加以及裂隙贯通4个阶段后发生宏观破坏。 相似文献
13.
为了解高压水渗流作用对裂隙岩体应力和变形的影响,结合黑麋峰抽水蓄能电站岩体高压压水试验的渗压及变形测试成果,采用多孔连续介质全耦合理论,研究了试验区岩体测点在压水孔加压和卸压过程中的孔隙压力和位移变化过程。通过对测点位移和渗压随时间变化过程的计算值和实测值对比研究,验证了所采用的水-岩耦合数值模型的合理性。研究表明：在压水孔内的水压力和岩体孔隙压力的共同作用下,岩体内的应力大幅度增加;压水过程中,岩体因渗流作用产生了较大的位移,停止压水后的一段时间内,由于岩体中还存在一定的孔隙水压力和水压力梯度,从而导致岩体内仍存在部分变形值,且该部分变形值并非是压水孔卸载后岩体内的塑性残余变形;高压水渗流作用下的岩体耦合效应对工程应力和围岩变形有重大影响,考虑水-岩耦合效应的岩体稳定性评价结果对工程设计更具指导意义 相似文献
14.
注浆堵水是地下工程和矿山水害防控的常用技术措施,但是,目前浆液扩散机理与采动效应的研究滞后于工程实践的要求,制约了注浆工程科学有效地实施。本文跟踪裂隙岩体中注浆浆液扩散研究,受裂隙地下水“偏流效应”启发,提出了深部矿山裂隙岩体动水注浆浆液扩散偏流效应的命题,包括2个关键科学问题: 裂隙岩体动水注浆浆液扩散偏流机理、偏流形成的“浆-岩”组合体采动变形破坏和渗透性变化机理。结合研究趋势,提出了跨学科综合研究方法。以典型矿山注浆防治水工程为背景,研究深部矿山水文地质结构及其采动时空演化,揭示裂隙岩体动水条件下注浆浆液扩散偏流机理及其影响因素,获得裂隙岩体内帷幕注浆形成的三维异形“浆-岩”组合体形态和力学特性,建立浆液偏流扩散数学模型,构建“浆-岩”组合体渗透性采动效应评价方法,为深部矿山水害防治和安全生产提供科学基础。 相似文献
15.
Based on a simulation of three-dimensional fracture networks and a superposition principle of liquid dissipation energy for fractured rock masses, a model of the fracture permeability tensor is proposed. An elastic constitutive model of rock fractures, considering fracture closure and dilation during shearing, is also proposed, based on the dilation angle of the fracture. Algorithms of flow-path searching and calculation of the effective flow coefficients for fracture networks are presented, together with a discussion on the influence of geometric parameters of the fractures (trace length, spacing, aperture, orientation and the number of fracture sets) on magnitude, anisotropy of hydraulic permeability and the size of a representative elementary volume (REV). The anisotropy of hydraulic permeability of fractured rock masses is mainly affected by orientation and the number of fracture sets, and the REV size is mainly influenced by trace length, spacing and the number of fracture sets. The results of studies on REV size and the influence of in-situ stress on hydraulic conductivity of the rock mass on the slope of Jinping-I hydropower station, China, are presented using the developed models and methods. The simulation results agreed well with the results obtained from field water-pressure measurements, with an error of less than 10 %. 相似文献
16.
A numerical model is described for coupled flow and mechanical deformation in fractured rock. The mechanical response of rock joints to changes in hydraulic pressure is strongly influenced by the geometric characteristics of the joint surfaces. The concept of this work is to combine straightforward finite element solutions with complex and realistic fracture surface geometry in order to reproduce the non-linear stress-deformation-permeability coupling that is commonly observed in fractures. Building on the numerous studies that have expanded the understanding of the key parameters needed to describe natural rough-walled fractures, new methods have been developed to generate a finite element mesh representing discrete fractures with realistic rough surface geometries embedded in a rock matrix. The finite element code GeoSys/Rockflow was then used to simulate the coupled effects of hydraulic stress, mechanical stress, and surface geometry on the evolving permeability of a single discrete fracture. The modeling concept was experimentally verified against examples from the literature. Modeling results were also compared to a simple interpenetration model. 相似文献
17.
A model for the stress‐dependent elastic wave velocity response of fractured rock mass is proposed based on experimental evidence of stress‐dependent fracture normal and shear stiffness. Previously proposed models and previous experimental studies on stress‐dependent fracture stiffness have been reviewed to provide a basis for the new model. Most of the existing stress‐dependent elastic wave velocity models are empirical, with model parameters that do not have clear physical meanings. To propose the new model, the rock mass is assumed to have randomly oriented microscopic fractures. In addition, the characteristic length of microfractures is assumed to be sufficiently short compared to the rock mass dimensions. The macroscopic stress‐dependent elastic wave velocity response is assumed to be attributed to the stress dependency of fracture stiffness. The stress‐dependent fracture normal stiffness is defined as a generalized power law function of effective normal stress, which is a modification of the Goodman's model. On the other hand, the stress dependency of fracture shear stiffness is modeled as a linear function of normal stress based on experimental data. Ultrasonic wave velocity responses of a dry core sample of Berea sandstone were tested at effective stresses ranging from 2 to 55 MPa. Visual observation of thin sections obtained from the Berea sandstone confirms that the assumptions made for microstructure of rock mass model are appropriate. It is shown that the model can describe the stress‐dependent ultrasonic wave velocity responses of dry Berea sandstone with a set of reasonable material parameter values. Published 2013. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
18.
《Geomechanics and Geoengineering》2013,8(1):39-56
Recently one of the most challenging problems for civil engineers is how to construct new structures/infrastructures adjacent pre-existing ones and how to evaluate the effect of the new construction on the pre-existing structures (so-called neighbouring construction). The Manifold Method (MM) is one of the discontinuum based numerical approaches to simulate the mechanical behaviour of fractured rock masses including large deformation/displacement along fractures as well as stress/strain conditions of the rock blocks/masses. In this study, the MM was used to investigate the stability of the cut slope in the highly fractured rock masses along one of the national roads in Japan, focusing on the effects of new construction on the pre-existing structures/infrastructures. The effect of reinforcement during the construction such as rock bolts, anchors, etc. was also investigated and evaluated quantitatively by numerical simulations using MM. 相似文献
19.
The role of shear dilation as a mechanism of enhancing fluid flow permeability in naturally fractured reservoirs was mainly recognized in the context of hot dry rock (HDR) geothermal reservoir stimulation. Simplified models based on shear slippage only were developed and their applications to evaluate HDR geothermal reservoir stimulation were reported. Research attention is recently focused to adjust this stimulation mechanism for naturally fractured oil and gas reservoirs which reserve vast resources worldwide. This paper develops the overall framework and basic formulations of this stimulation model for oil and gas reservoirs. Major computational modules include: natural fracture simulation, response analysis of stimulated fractures, average permeability estimation for the stimulated reservoir and prediction of an average flow direction. Natural fractures are simulated stochastically by implementing ‘fractal dimension’ concept. Natural fracture propagation and shear displacements are formulated by following computationally efficient approximate approaches interrelating in situ stresses, natural fracture parameters and stimulation pressure developed by fluid injection inside fractures. The average permeability of the stimulated reservoir is formulated as a function of discretized gridblock permeabilities by applying cubic law of fluid flow. The average reservoir elongation, or the flow direction, is expressed as a function of reservoir aspect ratio induced by directional permeability contributions. The natural fracture simulation module is verified by comparing its results with observed microseismic clouds in actual naturally fractured reservoirs. Permeability enhancement and reservoir growth are characterized with respect to stimulation pressure, in situ stresses and natural fracture density applying the model to two example reservoirs. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
20.
岩石流变力学的研究现状及其发展方向 总被引：2，自引：0，他引：2
从岩石单轴压缩流变试验、多轴压缩流变试验、拉伸断裂流变试验、岩体及结构面的剪切流变试验、以及流变试验中的各种影响因素等来评述岩石流变试验的研究进展。同时从经验模型、元件模型、损伤断裂模型、基于内时理论的流变模型以及弹粘塑性模型等来对岩石流变本构模型的发展进行了回顾。最后, 指出复杂应力路径下岩石的非线性流变、水力-应力耦合情况下的岩石流变、考虑各向异性的岩石流变等方面是今后需要进一步深入研究的问题。 相似文献