三向应力作用下节理岩体渗流-应力耦合特性

节理岩体渗流-应力耦合特性研究是岩石力学领域的重点和难点。水利水电工程与地下工程中天然节理岩体往往处于三向不等压应力状态,针对三向应力状态下节理岩体渗流-应力耦合特性研究较少。其中,单节理岩体渗流-应力耦合特性研究是基础。首先分析与探究了单节理岩体侧向应力作用效果及渗流作用机制,在单节理岩体渗透性-应力耦合分析模型基础上推导了单节理岩体渗流-应力耦合的理论公式。通过室内真三轴渗流-应力耦合试验,基于全局优化算法的非线性拟合及块体离散元数值仿真,验证了所提出理论公式的合理性。基于电路原理,给出了模拟电路与渗流问题的相似物理量,通过引入等效渗流阻方法,探究了典型的含正六边形主干节理网络的渗流-应力耦合特性。该研究结果对实际工程岩体的渗流分析有一定的参考价值。     

葛洲坝红色岩体地质构造特征与岩体强度特性

本文利用岩体力学与地质力学相结合的理论和方法,对葛洲坝红色岩体的地质构造特征与岩体力学特性之间的关系进行了研究,获得了该岩体强度特性及其形成机理。提出了地质构造形迹是构成工程岩体力学问题和形成岩体特性的一个重要因素。本文所采取的研究途径和研究结果,对于岩体工程实践和岩体力学理论研究具有重要意义。     

大理岩卸载力学特性的研究

本文针对洞室,矿山边坡等一些工程的岩体应力变化状况,研究三轴卸载试验的应力路径,并提出以储备强度的概念进行资料整理,从而得出了轴、侧应力同时卸载下的岩石变形特性的特殊性.结果表明,用符合于岩体工程应力变化的加载路径来求取岩体的力学特性是十分必要的.     

金川露天矿边坡岩体移动和变形的光弹性软材料模拟实验研究

通过对边坡岩体破坏机理的光弹性力学模拟实验研究, 岩体在地应力作用和自重体积力作用下, 对露天矿边坡的力学状态具有明显地影响。实验采用了明胶软材料, 模型比例1:1100。实验模拟了在自重应力和构造应力作用下, 边坡岩体的位移和变形。     

裂隙岩体宏观力学参数的二维数值模拟

岩体通常含许多不同尺度的裂隙,因而力学性质非常复杂。由于现场测试及常规实验室试验常受各种条件的限制,因而其不能准确反映岩体的宏观物理力学性质。本文基于有限元分析软件对二维情况下的完整岩体和含不同倾角的软弱夹层的岩体在单轴和双轴压缩下进行了数值模拟,得到岩体变形的应力-应变曲线。该类曲线能反映裂隙对岩体力学参数的影响,对于指导工程实践有一定的意义,并且为获取岩体力学参数提供了新的途径。     

Cosserat介质理论针对节理岩体的应用

由于考虑了内在尺度的影响,Cosserat介质理论较传统连续介质力学更精确和一般化,在考虑具有微结构介质的力学行为时拥有优势.节理岩体的力学性质明显受结构面影响控制,传统连续介质理论对于认识结构应力、应变的真实状况是有限度的.Cosserat理论应用于岩土介质模拟时,根据具体情况有三种方式一种是将岩土介质视为粒状材料,第二种则是将节理岩体看作是层状材料,此种模型应用最为常见;另一种则是将高度节理化岩体看作是块体结构.与试验或其它数值计算的对比表明,采用层状和块状模型对节理岩体进行数值模拟得到的分析成果是合理可信的.空间模型的应用也作了讨论.     

岩石的记忆功能及对岩体变形的影响

岩石的记忆功能包括残余应力对材料力学性质的影响, 应力的冻结特性和对固结应力的记忆。本文叙述这三类应力的理论基础、力学特性和计算方法, 通过一些工程算例指明其对岩体变形及岩体稳定性分析的重要性。     

单轴压应力下砂岩岩块的变形和破坏研究

一、研究的目的和内容重视宏观的和微观的地质因素的岩体力学试验研究,有助于较真实地解释和确定岩块和岩体的变形、破坏的机理和力学的宏观现象,可以为选择和建立它们的破坏准则和强度理论,进行地壳岩体和工程岩体的稳定性分析评价等提供有用资料. 岩体是由宏观的结构面和结构体所构成,是地质体的一部分.岩体中包含着岩块.岩块和岩体的建造和改造决定了它们的物质组成和结构构造.     

σ-τ平面上莫尔理论的修正

在莫尔理论中如何引进中间主应力σ2的影响一直是长期困扰力学界的一个问题,由此产生了在σ-τ平面上难以界定某些状态下应力圆的破损界线。以静水应力σm对结合力和滑移的影响观点,将二参数的莫尔定理修正为三参数形式后,分析了它在σ-τ平面上的应用,为引进中间主应力σ2的影响提供了新途径。     

在层状岩体中柱面波的传播

近些年来,随着复合材料生产的发展,复合材料力学性质的理论和实验研究也相应地发展起来了.由于许多岩体是复合体,因此运用复合材料力学理论的基本原理和方法来处理岩石力学问题是很有意义的,它更能比较真实地反映岩体的力学特性.最近,有些人已开始做了这方面的研究工作.     

In Situ Study on Stress in Rock Mass

The Significance of the rock stress measurements for studying state of stress in the crust is elucidated in this paper .A brief introduction on the principles and methods of calculating the rock stress by measuring the deformations of the bore-holes by means of the overcoring technique is given .Generally the error is estimated to be about 10% by the laboratory checking methods .Form the practical examples it is summed up for some laws of the stress distribution within 200 meters of the shallow crust: from the viewpoint of the rock-mass strength and energy accumulation, the relationship between the major principal stress and the elastic modules of the rock is shown in diagrams, and its direction is closed related to the topographical conditions .The practical examples reveal the measurement of rock stress is significant to the ground surface and underground engineering projects .     

声发射预报地震的岩体力学分析

岩体受压破坏是由于岩体内裂纹扩展及新的宏观裂纹产生不断积累的结果,大规模岩体受压破坏前会发生局部岩体的先前断裂破坏。裂纹起裂、快速扩展和止裂会产生声发射现象,局部岩体断裂破坏会产生强烈的声发射现象,通过对岩体声发射的监测分析可以预报受压岩体破坏的时间。因此,通过对地壳岩体声发射的监测分析,可以进行地震的短期和临震预报。通过对岩体受压应力分布规律的分析,得出通过监测地壳浅部地应力和地形变预报地震是没有实际意义的结论。     

Computational simulation of seepage instability problems in fluid-saturated porous rocks: Potential dynamic mechanisms for controlling mineralisation patterns

Pore-fluid flow associated with seepage instabilities can play an important role in controlling large mineralisation patterns within the upper crust of the Earth. To demonstrate this process, two kinds of seepage instability problems in fluid-saturated porous rocks are considered in this paper. The first kind of seepage instability problem is caused by the temperature-induced buoyancy of pore fluid, so that it can be called the buoyancy-driven seepage instability problem, while the second kind of seepage instability problem is caused by chemical dissolution reactions that are commonly encountered in the upper crust of the Earth, so that it can be called the chemical-dissolution-driven seepage instability problem. After the mathematical governing equations of and computational methods for these two kinds of seepage instability problems are introduced, two numerical examples are used to elucidate how and why these two kinds of seepage instabilities can provide favorable places for the formation of large mineralisation patterns within the upper crust of the Earth. The related computational simulation results have demonstrated that: (1) the convective pore-fluid flow caused by the buoyancy-driven seepage instability not only can dissolve minerals at the lower part of the upper crust, but also can transport the dissolved minerals from the lower part to the upper part of the upper crust, resulting in large mineralisation patterns near the surface of the Earth's upper crust. (2) The chemical-dissolution-driven seepage instability in fluid-saturated porous rock can provide some favorable places, such as finger-like channels created by porosity enhancement in the porous rock, for the formation of large mineralisation patterns within the upper crust of the Earth.     

二十年岩体应力现场实测研究

本文介绍了几个现场应力量测实例,并将其划分为三种类型:低强度岩体中应力;高强度岩体中应力;高应力地区岩体中应力。被测岩体包括各种各样的沉积岩、火成岩和变质岩,它们的杨氏模量介于1—105 GPa。用于应力解除的最深钻孔为90.7m。根据上述实测结果及简单分析计算,归纳出初始应力在地壳浅部分布的一般规律,论述了初始应力与岩石杨氏模量的关系及其对岩体工程的影响。     

Study of Stress Measurement In-situ in the Last Two Decades

Various typical results are introduced of in-situ stress measurements by overcoming tests during last two decades. The stress cases could be divided into three types: in-situ stress in lower strength rock; in-situ stress in higher strength rocks; in-situ stress in high stress region. The involved rock masses were variety of Sedimentary rock, Igneous rock, and Metamorphic rock with yang’s modulus from 1 to 105GPa. The deepest borehole used for stress release was 90.7 m. Some general laws of initial stress in the shallow earth crust were drawn from the above results. The relationship between initial stress and yang’s modulus of rocks and the influence of initial stresses on rock engineering are discussed.     

Evaluation of equivalent medium methods for stress wave propagation in jointed rock mass

This paper evaluates the existing equivalent medium methods for jointed rock mass and further develops the equivalent viscoelastic medium method proposed by the authors. The advantages and limitations of different equivalences to the discontinuous rock mass are discussed. Theoretical derivation of stress wave propagation through the equivalent viscoelastic medium is carried out by adopting the Fourier transformation method, and the parameters of the equivalent viscoelastic medium method are determined analytically. The frequency dependence and the wave attenuation phenomenon can be properly described when the imaginary terms of the complex moduli of the rock mass are included. The results show that the equivalent viscoelastic medium method is able to predict the effective velocity and the stress wave transmission coefficient in a rock mass more accurately than the conventional effective elastic moduli methods. An example of the stress wave propagation through rock mass with parallel joints shows that the equivalent viscoelastic medium method is promising and worthy to be further explored for application in practical rock engineering problems. Copyright © 2011 John Wiley & Sons, Ltd.     

应变软化在甘肃红柳河辉长质糜棱岩形成中的作用

本文论述的辉长质糜棱岩发现于甘肃北山红柳河蛇绿岩套中。在简单说明了糜棱岩的地质背景及特征、描述了变形岩石的显微构造特征之后，重点对糜棱岩形成过程中的应变软化机制作了论述。探讨了软化岩的存在、组构调整、粒度缩小，长石的动态重结晶，水以及主导变形机制的不断调整与转化等应变软化机制，在应力作用下使岩石逐步软化过程中所起的作用，得出这种糜棱岩是在拆离剪切作用下，应力在蛇绿岩中的软化岩石辉长岩中集中，从而形     

层状地壳的等效力学模量和分层应力

针对地球动力学研究中的板壳力学模型的分层问题,根据等效原则, 给出了用各分层弹性参数和厚度表示的中性面位置、折合抗弯刚度和等效弹性参数。结合实际地壳受横向和侧向力作用时产生的弯曲形变和应力,具体介绍了用这种折算模量的方法去求解地壳中的应力、应变状态, 并通过比较等效应力与各分层应力的差异, 阐明了岩石力学性质的不同对各圈层应力的影响作用。研究进一步表明,来自地壳深部的垂直向上的力是造成上部地壳伸展类构造的重要因素之一。     

Open Fissure Folds record coseismic loading and postseismic stress relaxation

Open Fissure Folds hosted by high pressure/low temperature metamorphic rocks of south Evia (Greece) are introduced, their structural and microstructural record is analysed, and a mechanical model is proposed. Open Fissure Folds are preserved as at least two parallel folded quartz–feldspar veins separated by narrow buckled rock columns. The veins originated as tensile cracks that propagated in the middle crust driven by high differential stress. Features diagnostic for Open Fissure Folds indicate that the rock columns represented the layers of high viscosity, and not the veins as consistently reported in many previous studies on folded veins. This record is taken to indicate that buckling of the rock columns initiated after arrest of the fractures and terminated prior to complete vein sealing. Accordingly, mechanical decoupling by open fissures allowed for buckling of the rock columns in response to episodic creep of the host rocks according to stress relaxation, as expected for postseismic deformation in the earthquake cycle. I propose that the parental fractures propagated in response to quasi-instantaneous coseismic loading of the middle crust. Buckling was attributed to transient postseismic creep and stress relaxation. Complete sealing of the veins occurred when stresses were largely relaxed. Each Open Fissure Fold records the stress and strain history of a single earthquake.