用渗透性随深度变化规律确定大尺度岩体变形模量

采用渗流场-应力场耦合的观点,用表征渗透性的单位吸水量数据,反求了岩体宏观力学参数——岩体变形模量。裂隙岩体的渗透性大小是裂隙宽度的函数,而岩体不同深度的裂隙宽度由应力大小和变形模量决定,因此可以通过裂隙宽度把渗透性参数和岩体力学参数结合起来。以小浪底水库左岸砂泥岩裂隙岩体T41地层为实例研究表明,该方法求得的岩体变形模量符合随着应力增大而增加这一规律,也符合风化岩体变形模量相对较小这一规律,并且数量级与收集到的相近岩体的变形模量一致,因此所求结果是可靠的。     

脆性岩石侧向变形特征及损伤机理研究

进行了三峡花岗岩常规三轴压缩、保持轴向应变和保持轴向应力的卸围压试验,研究了脆性岩石在不同应力路径和不同加载控制方式下的侧向变形特征,可见临界侧向应变均稳定在（?0.004 ? 0.000 5）范围内。进一步进行三峡花岗岩的全过程应力-应变曲线和损伤力学分析,发现脆性岩石在不同应力路径和不同加载控制方式下均以侧向损伤为主,且侧向损伤曲线的形态近似,达到临界破坏状态时损伤值稳定在0.7?0.8左右。最后以侧向损伤变量表征花岗岩脆性破坏过程,建立了基于应变空间的、可以考虑卸荷应力路径的损伤模型和应变型破坏准则。     

Coupling between anisotropic damage and permeability variation in brittle rocks

In this paper, a coupled constitutive model is proposed for anisotropic damage and permeability variation in brittle rocks under deviatoric compressive stresses. The formulation of the model is based on experimental evidences and main physical mechanisms involved in the scale of microcracks are taken into account. The proposed model is expressed in the macroscopic framework and can be easily implemented for engineering application. The macroscopic free enthalpy of cracked solid is first determined by approximating crack distribution by a second‐order damage tensor. The effective elastic properties of damaged material are then derived from the free enthalpy function. The damage evolution is related to the crack growth in multiple orientations. A pragmatic approach inspired from fracture mechanics is used for the formulation of the crack propagation criterion. Compressive stress induced crack opening is taken into account and leads to macroscopic volumetric dilatancy and permeability variation. The overall permeability tensor of cracked material is determined using a micro–macro averaging procedure. Darcy's law is used for fluid flow at the macroscopic scale whereas laminar flow is assumed at the microcrack scale. Hydraulic connectivity of cracks increases with crack growth. The proposed model is applied to the Lac du Bonnet granite. Generally, good agreement is observed between numerical simulations and experimental data. Copyright © 2005 John Wiley & Sons, Ltd.     

深埋脆性岩石力学参数评估与变形特性探讨

隧道工程开挖深度有逐渐增加的趋势,深部岩石具高强度及高应力环境。虽然脆性岩石在高围压应力下,将转而呈现延性特性,但隧道开挖所产生的径向解压,使隧道周边一定范围内的岩体处在低围压状态,故这部分围岩的变形仍由脆性性质所掌控。对于脆性岩石呈现峰后强度弱化特性,文中汇整各种岩石峰后强度弱化参数评估方法后,提出结合Hoek-Brown准则与岩心试验的强度损失试验评估法。以实际工程案例分析结果显示,600 m埋深时岩石峰后强度弱化与否,对隧道围岩变形量影响不大,但隧道埋深超过2 000 m后,变形量的差异将达到3～4倍左右,显示脆性岩石峰后强度弱化特性,对深埋隧道施工变形影响不可忽视。     

The mechanism of the deformation memory effect and the deformation rate analysis in layered rock in the low stress region

We propose a new mechanism to explain the deformation memory effect based on sliding over pre-existing sliding planes. Sliding resistance can comprise an element of cohesion and an element of frictional resistance. In this model only the cohesion is considered. The mechanism is modelled for a particular case of parallel sliding planes typical for layered rocks. The model consists of a number of identical basic elements comprising two springs, a St. Venant body and a dashpot. The basic elements only differ in their cohesion. The loading regime incorporating the influence of the delay time was modelled with one, two and 500 basic elements. The results showed that the recoverable stress magnitudes were in the range between the minimum and twice the maximum of cohesion. The model demonstrates the experimentally observed memory fading whereby the fidelity of stress reconstruction reduces with the increase in the time delay between the previous load the rock was subjected to and the measuring cycles.     

岩石破坏非连续变形分析弹脆性本构模型的二次开发

岩石非连续变形分析方法DDARF成功实现了模拟岩体裂纹萌生、扩展、贯通、破碎的全过程,但算法只考虑了岩体的线弹性本构模型,没有分析岩体的非线性应力-应变关系。为更符合真实岩体工程,同时扩展岩石非线性本构模型的应用范围,分别采用摩尔-库仑强度准则和最大拉应力强度准则对岩体进行剪切和拉伸破坏判断;对理想弹脆性本构模型进行算法分析,并在VC++平台下程序实现;对“自定义”的岩体非连续变形分析方法弹脆性本构模型与室内单轴压缩试验进行比较分析;将岩体非连续变形分析方法弹脆性本构模型应用于大型地下洞室开挖,并与线弹性本构模型进行对比。结果表明,非连续变形分析方法中自定义岩体弹脆性本构模型是可行的,它能够反映岩体变形的非线性特征,与室内试验吻合度较好;非连续变形分析方法弹脆性本构模型应用于大型地下工程,能更安全且真实地分析洞室围岩的稳定性,进而更好地指导地下洞室的防护措施。     

岩石变形破坏过程中渗透率演化规律的试验研究

利用伺服试验机对灰岩和砂岩进行了应力应变全过程渗透性试验,研究了岩样变形和破坏过程中的轴向应变与渗透率之间的关系,分析了岩样环向应变对渗透率的影响规律,探讨了岩样变形破坏前后渗透压差随时间的变化关系。结果表明,岩样渗透率与应力状态密切相关,渗透率的峰值滞后或超前于应力应变峰值,这与岩石介质本身的特性有关;渗透率-环向应变曲线与渗透率-轴向应变曲线有相同的变化趋势,但岩石环向变形比轴向变形更能灵敏地反映渗透率的演化规律;岩样变形破坏峰值前后的渗透压差与时间均遵循负指数关系。最后对岩石变形破坏过程中的渗透机理作了讨论。     

The initiation of brittle faults in crystalline rock

Faults in the upper crust initiate from pre-existing (inherited) or precursory (early-formed) structures and typically grow by the mechanical interaction and linkage of these structures. In crystalline rock, rock architecture, composition, cooling, and exhumation influence the initiation of faults, with contrasting styles observed in plutonic rocks, extrusive igneous rocks, and foliated metamorphic rocks. Brittle fault growth in granitic rock is commonly controlled by the architecture of inherited joints or preexisting dikes. In basalt, abundant joints control the surface expression of faulting, and enhanced compliance due to abundant joints leads to folding and deformation asymmetry in the fault zone. Highly reactive mafic minerals likely become rapidly evolving fault rocks. In foliated metamorphic rocks, fault initiation style is strongly influenced by strength anisotropy relative to the principal stress directions, with fracturing favored when the foliation is aligned with the directions of principal stress. The continuity of micas within the foliation also influences the micromechanics of fault initiation. Brittle kink bands are an example of a strain-hardening precursory structure unique to foliated rock. Each of these fault initiation processes produces different initial fault geometry and spatial heterogeneity that influence such properties as fault permeability and seismogenesis.     

反倾岩体边坡变形机制与稳定性评价研究综述

随着人类工程活动的日益频繁及范围的扩大,在国内外的水利水电、矿山、铁路、城市环境灾害等方面都出现了大量反倾向边坡失稳破坏的灾难性事故,然而这种广泛存在的反倾向岩体边坡的工程地质问题在二十世纪六十年代初才逐步被人们认识到和加以研究。本文就国内外反倾岩体边坡变形机制与规律认识,以及解析解、数值模拟和物理模拟等稳定性评价方法的研究进展进行了系统总结,对有待深入思考的问题和可能的研究途径进行了探讨     

饱水岩石加载变形过程中视电阻率–渗透率的关联性

根据岩石受载变形破坏过程中视电阻率和渗透率的演化规律,分析了岩体破坏过程中视电阻率和渗透率变化的关联性,指出饱水条件下岩石变形破坏过程中视电阻率与渗透率关系密切.基于Archie公式和Carman-Kozeny公式,推导出了饱水岩石渗透率和视电阻率之间的关系式.同时,从岩石加载过程变形破坏的细观分析角度,探讨了渗透率-视电阻率关系式的合理性,进而指出了其成立的基础条件和应用意义.     

Constraining absolute deformation ages: the relationship between deformation mechanisms and isotope systematics

Isotope diffusion in a mineral is strongly temperature dependent but is also a function of grain size. Deformation must, therefore, be an important consideration in the interpretation of isotopic data because it provides a means of modifying grain size and shape. We illustrate the range of different deformation mechanisms common in micas and use simple models to investigate the relationship between these and isotope diffusion. We consider three different thermal scenarios with deformation taking place during: (a) the prograde heating path, (b) at the closure temperature of the deforming mineral, and (c) at temperatures significantly below the closure temperature. We have modelled these simple systems using a finite difference algorithm that simulates argon diffusion profiles and bulk ages. This modelling illustrates that obtaining deformation ages is critically dependent on an understanding and recognition of the different deformation mechanisms that have affected the sample. In the cases where deformation causes a change in grain size, it is important to characterise both the temperature at which deformation takes place and the closure temperature of grains formed during the deformation. The development of grains with T_c greater than the deformation temperature may record a deformation age. Examples of this condition include: (i) neocrystallisation; (ii) grain size reduction occurring at temperatures below T_c (of the reduced grain size) where the deformation mechanism has reset the grains; and (iii) deformation-induced grain coarsening.     

采矿巷道围岩变形机制数值模拟研究

研究了大冶铁矿龙洞-62 m、-74 m水平采矿巷道开挖后的二次应力分布及巷道变形机制。首先根据现场工程地质勘查和室内岩石力学试验对巷道围岩进行了工程地质分组和岩石力学参数确定;在此基础上运用FLAC3D数值模拟软件研究了巷道开挖后的应力应变状态,分析了围岩变形机制;并根据-74 m水平采矿巷道的收敛监测数据对比验证了数值模拟结果。研究结果表明,围岩条件不同的采矿巷道其二次应力分布影响范围有所差异,但围岩主应力总体上表现为由巷道边墙中下部位的压应力集中带逐步过渡到拱顶、底板一定范围内的拉应力集中带。     

不同连通率断续节理岩体直剪破坏特征

采用水刀切割加工灰岩原样,开展含Z型相交裂隙试样的室内直剪试验,系统地研究了剪应力-剪位移曲线,分析了预制裂隙倾角和法向应力对含Z型相交裂隙试样强度、变形及裂纹扩展的影响,并阐明了含Z型相交裂隙试样破坏演化机制。研究表明：①剪应力-剪位移曲线可分为预制裂隙(孔隙)压实阶段(初期下凹)、准线性变形阶段(中期线性波动)、峰前不稳定断裂发展阶段(后期上凸)及峰后强度残余阶段(陡降)4个变形破坏阶段;②相同裂隙倾角下裂隙岩体的峰值剪应力随法向应力增大而增大(近线性),且相同法向压力下裂隙岩体的峰值剪应力随裂隙倾角增大而减小(趋势渐缓);③裂隙宏观损伤裂纹演化过程可分为初始压密弹性阶段、裂纹扩展增长阶段及贯通断裂破坏阶段,且其破坏模式包括拉伸破坏、剪切破坏及拉剪混合破坏(拉伸-剪切贯通和剪切-拉伸-剪切贯通)。     

多层软弱夹层边坡岩体破坏机制与稳定性研究

以大量的实际工程为基础,基于Sarma极限平衡法和有限元强度折减法探讨层状岩质边坡在不同岩层倾角θ、边坡坡角β、结构面间距h条件下的安全系数与破坏面位置的变化规律,揭示复杂多层软弱夹层边坡岩体的破坏机制及稳定性特征。结果表明：不同θ条件下边坡岩体失稳机制和破坏面位置不同,随着θ的增大,破坏机制表现为滑移破坏→滑劈破坏→崩塌破坏→倾倒破坏→滑移破坏;当β、h一定时,直立层状边坡的稳定性略大于水平层状边坡,反倾向边坡的稳定性明显大于顺层边坡;β直接影响边坡岩体破坏特征,当β由30°增大至60°时,顺层边坡的安全系数约降低53%;反倾向层状边坡的安全系数约降低40%;h对边坡岩体破坏机制的影响较小,但对稳定性的影响较大,建议工程实践中加强密集结构面岩质边坡的监测和加固工作。     

地震活动与矿井顶板事故影响关系统计分析

针对地震活动与顶板事故进行时空序列统计分析,得出两点新认识:(1)顶板事故与宏观地震序列有较强的频率对应,似乎是"遥相呼应";(2)相当多的顶板事故伴随有周边小震发生。推测部分原因是这些矿井位于地震带附近,部分原因是采矿卸压引发矿震,一些地震可能是宏观地震序列中的一部分。如果能够掌握,并加以利用,对于安全生产具有一定意义:对既定煤田,查找周边对矿区地应力影响强烈的地震带或断裂带,这些矿井顶板事故有可能成为周边地震带或断裂带的"应力窗",而地震带或断裂带的活动又成为煤矿地质灾害的"晴雨表"。在煤田大区,可以把顶板事故群发当作构造应力扰动的一种反映,作为大区构造应力扰动传入矿区,再与开采卸压作用叠加,引起地质灾害的证据。     

偏高岭土与水泥砂土渗透性关系分析

以探究偏高岭土与水泥砂土渗透性(渗透系数值)的关系为主要内容,选择合适的外掺比例用于工程实践。通过设计对比试验,选择偏高岭土的外掺比例分别为0.0%、1.0%、2.0%、3.0%、4.0%、5.0%等6组试验组,分析试验数据并作图对比。最后得到如下2个结论:外掺偏高岭土后提升了水泥土的抗渗性能,尤其可大幅度提升水泥土前期抗渗性能,且外掺比例3.0%时效果最佳。外掺偏高岭土后并不影响水泥渗透系数值与养护龄期呈负相关的关系,外掺偏高岭土的水泥砂土的渗透系数值在35 d后基本维持不变。     

岩体波速与坝基岩体变形模量关系

岩体变形模量是岩体工程设计最重要的参数之一,尽管其可以通过各种现场试验来获得,但因其耗时、费力、投资大,使得许多中小型工程及大型工程的初步设计阶段无法通过试验来得到这一参数。因此,许多研究者建立了诸多岩体变形模量与岩体物理力学参数或岩体质量分级之间的相关关系,如岩体变形模量与RQD、RMR分级、Q分级、岩体纵波速度等之间的关系,从而利用这些关系估算岩体变形模量。总结了已有估算岩体变形模量的各种方法,讨论了其应用条件及预测结果,重点分析了利用岩体纵波速度估算岩体变形模量的方法及存在的问题,并以玛尔挡坝址为实例,建立了相关预测公式。通过与已有估算方法的对比研究,阐明了各种方法预测结果的异同,表明其建立的估算公式与Barton等公式具有较好的一致性,可以用来估算岩体的变形模量     

含软弱夹层层状隧道围岩变形机理研究

堡镇隧道地质条件复杂,局部地段处于高应力区,围岩变形具有变形速度快、变形量大且破坏严重、持续时间长的特征。通过对堡镇隧道左线出口段围岩变形量测资料和掌子面地质素描的比较分析后发现,不论强度高、节理裂隙发育的砂质页岩,还是处于高地应力、强度低、围岩破碎的炭质页岩,掌子面有软弱夹层分布时,其变形破坏程度较相邻段同类围岩严重的多。因此,依据软弱夹层与掌子面围岩的典型组合情况,结合堡镇隧道所揭示的不同围岩室内三轴试验结果,建立了含软弱夹层围岩的力学模型,探讨了含软弱夹层围岩变形破坏的形成演化过程,揭示了高地应力条件下软弱夹层引起围岩变形失稳的机理。     

Coupling between fluids and rock deformation in the continental crust:Preface

正1.Introduction Fluids are essential and widespread components of the Earth crust.They regulate the main process of mass and energy transport,conditioning the geochemical and geophysical evolution of the crust (Bredehoeft and Norton.1990) and,consequently,its properties and mechanical behavior.The coupling between fluids,rock deformation,and heat are crucial engines for plate tectonics,playing a leading role in the rheology and evolution of the lithosphere(e.g.Jamtveit et al.,2000;Kennedy and van Soest,2007;Thompson,2010;Miller.2013;Yardley and Bodnar,2014:Hirauchi et al.,2016: