共查询到16条相似文献，搜索用时 140 毫秒
1.
节理滑移时其渗透率的演化特性是岩体水力特性重要的科学问题之一。为了深入了解花岗岩节理在高应力条件下剪切滑移时渗透率的变化规律,对花岗岩耦合节理剪切时的渗透率进行了试验研究。为了解决剪切时高压孔隙流体的密封问题及节理渗透率测量问题,设计了一种适用于高压孔隙流体作用下的剪切渗流试验系统。通过剪切渗流试验获得了渗透率随剪切位移的变化规律,以及剪切应力和法向变形与剪切位移的关系。试验结果表明:高应力条件下剪切峰后节理发生明显的剪胀,但其渗透率呈降低趋势;节理剪切过程中节理的剪胀、压缩和凸起的剪断磨损机制共同影响渗透率的变化;高应力一方面限制了节理的剪胀特性,另一方面也增强了凸起的剪断磨损机制,因此,节理剪切时节理渗透性被显著降低。 相似文献
2.
岩石节理的渗流广义立方定理 总被引：29，自引：5，他引：29
首先讨论了岩石节理的渗流立方定理及其适用条件，然后从渗流与变形耦合的角度，论述了节理的开度性质，并提出了适用于一般节理的渗流广义立方定理，最后用有限元数值模拟方法验证了广义立方定理。 相似文献
3.
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
4.
岩石节理剪切变形对岩体工程的安全性和稳定性具有重要影响。为研究常法向应力下岩石节理剪切变形本构关系,采用RDS-200型岩石直剪仪对非规则砂岩节理进行了不同法向应力下的直剪试验。根据岩石节理剪切应力?位移全程曲线形状特征,将其依次划分为峰前压密阶段、线性阶段、屈服阶段和峰后软化阶段;根据剪切应力在峰后软化阶段降低幅度和速率大小,将岩石节理剪切应力?位移曲线划分为3种类型：峰后平台型、峰后缓降型和峰后跌落型。基于岩石节理剪切应力?位移曲线各阶段剪切变形特征,采用分段函数建立了岩石节理剪切变形本构模型。与其他模型相比,新提出的岩石节理剪切变形本构模型对试验数据拟合精度更高,更好地描述了岩石节理剪切应力?位移全程曲线。另外,在通过岩石节理直剪试验由经验公式确定模型参数之后,所提出本构模型可在不同法向应力下实现对不同粗糙度岩石节理剪切应力?位移曲线的预测。研究结果对岩石节理剪切变形的数值模拟和工程估计具有一定的实用价值。 相似文献
5.
渗透水压对节理应力-渗流耦合特性的影响试验研究 总被引：1，自引：0，他引：1
为研究渗透水压对节理应力-渗流耦合特性的影响,通过对6组人造节理试件恒定法向载荷和恒定法向刚度的压剪渗流试验,分析了应力和位移、节理水力开度以及透过率随剪切位移的变化趋势,获得了渗透水压对节理岩石应力-渗流耦合特性的影响规律。结果表明：节理试件的剪切应力和位移、水力开度以及透过率都与渗透水压密切相关。剪切应力随渗透水压的增大而减小,法向变形、水力开度和透过率却随渗透水压的增大而增大。在压剪渗流试验过程中,不同渗透压力的节理试件都发生了剪胀效应。研究可为深部岩体工程围岩遇水作用稳定性及渗流灾害控制技术提供科学的理论依据。 相似文献
6.
循环剪切荷载作用下岩石节理变形特性试验研究 总被引：1，自引：0，他引：1
以水泥砂浆为相似材料,制备3种岩壁强度、5种起伏角度的锯齿型节理试样;利用试验设备,进行了在4种法向应力下的循环剪切试验。根据试验结果,结合循环剪切试验特点,定义剪胀角来表征节理循环剪切的法向变形特性,以及剪切刚度来表征节理循环剪切的切向变形特性。基于不同起伏角、不同强度等级和不同法向应力下的节理试样循环剪切试验结果,分析了循环剪切过程中剪胀角和剪切刚度的变化规律;并利用不同条件下的试验结果,对比分析初始起伏角度、法向应力、岩壁强度对节理循环剪切变形特性的影响规律。研究发现：剪胀角、剪切刚度均随着剪切循环次数的增加而呈现先快、后慢的降低趋势,并且中低起伏角度节理的剪胀角、剪切刚度的降低趋势随着初始起伏角度、法向应力的增加而加快,随着岩壁强度增加而变慢,高起伏角度节理的剪胀角、剪切刚度的降低趋势基本保持不变。 相似文献
7.
节理在固定法向压力刚度（CNS）条件下的剪切过程比较复杂,剪切中由于剪胀的存在使得法向压力增大,而法向压力的增加又限制了剪胀的发生。根据CNS剪切过程中某一瞬时状态下法向压应力大小,以节理在该法向压应力下法向剪胀位移与剪切位移的关系为基础,建立一个楔形物理模型。通过循环迭代求得CNS剪切过程中每一步的法向压应力值,进而得到整个过程的剪切应力值。通过该模型,讨论了节理各参数对CNS剪切过程的影响,结果表明,其剪切应力值受法向压应力刚度与节理法向变形参数共同协调控制（包括单轴压缩变形及剪胀角的磨损）,节理在剪切过程中越不易发生压缩变形,其剪切应力值越大。 相似文献
8.
节理岩体蠕变特性研究 总被引：13，自引：3，他引：10
在已知岩石和节理蠕变规律的前提下,推导了节理岩体蠕变模型的一般表达式。假定岩石体积变形和节理法向压缩变形为弹性变形,忽略节理的剪胀现象,认为只有岩石畸变和节理剪切滑移与时间有关,从而推导了含三组相交节理的岩体蠕变模型及其参数。根据反演出的岩石和节理蠕变模型,计算了含三组相交节理的岩体在单轴应力作用下一些节理参数对岩体单轴蠕变的影响。分析表明,节理间距、剪胀系数以及节理夹角都对岩体的单轴蠕变变形有明显影响。节理间距越大,剪胀系数越大,节理夹角越小,节理岩体的单轴蠕变柔量也就越小,岩体的蠕变变形也越小。 相似文献
9.
《岩土力学》2020,(1)
为研究常刚度(CNS)边界条件下节理的剪切-渗流耦合特性,针对3种不同节理粗糙度的复制节理试样进行了3种不同刚度、3种不同渗透水压力条件下的剪切-渗流试验,全面系统地分析了法向刚度、渗透水压和节理粗糙度等因素对节理剪切过程中力学特性和渗流特性的影响。试验结果表明:节理峰值剪切强度随法向刚度的增加而增加,流量、等效水力开度和透过率随法向刚度的增加而减小;节理峰值剪切强度和法向位移均随渗透水压的增大而减小,流量、等效水力开度和透过率随法向刚度的增加而增加;通过节理面的流量随节理粗糙度的增加而减小。剪切过程中流量、等效水力开度和透过率均呈现类似于节理剪胀的三阶段变化规律:快速增长阶段、增速变缓阶段和稳定阶段;稳定阶段流量随法向刚度和渗透水压的变化近似呈线性关系,随着渗透水压的增加,粗糙程度较高的节理流速较慢。 相似文献
10.
为研究不同边界条件下剪切速率对岩石节理剪切力学特性的影响,采用RDS-200型岩石节理剪切试验系统对人工浇筑的具有相同节理形貌的不规则水泥节理试样进行了常法向应力和常法向刚度2种边界条件下5种剪切速率的直剪试验。结果表明：（1）常法向应力边界条件下,随剪切速率增大,相同法向应力下的类岩石节理峰前剪切刚度减速增大,峰值剪切强度和残余剪切强度呈对数降低;随剪切速率增大,类岩石节理黏聚力减速增大,内摩擦角呈对数降低。（2）常法向刚度边界条件下,随剪切速率增大,相同法向应力的类岩石节理峰前剪切刚度减速增大,峰值剪切强度呈对数降低,较高法向应力下的残余剪切强度先增大后减小;随剪切速率增大,类岩石节理黏聚力呈对数降低,内摩擦角减速增大。（3）与常法向应力边界条件相比,常法向刚度条件下,节理黏聚力平均增加了115.85%,内摩擦角平均降低了8.44%;相同初始法向应力和剪切速率下,峰前剪切刚度、峰值剪切强度和残余剪切强度分别平均增加了11.96%、19.47%和32.32%,峰值法向位移平均降低了40.12%。该研究结论可为不同剪切速率下地表和地下工程岩体节理的剪切失稳评价提供一定参考。 相似文献
11.
在岩土工程中,裂隙岩体经常处于峰后变形状态,研究裂隙岩体的峰后应力-应变关系对预测结构的稳定性有重要意义。基于峰后软化阶段强度参数的逐渐演化行为,首先提出一个求岩石峰后应力-应变关系和裂隙峰后应力-切向位移关系的一般方法。然后采用摩尔-库仑强度准则,以岩石的最大主应变和裂隙的切向位移作为软化参数,假设强度参数为软化参数的分段线性函数,分岩体沿裂隙滑移破坏和沿岩石剪切破坏两种情况,提出多组贯穿裂隙岩体峰后应力-应变关系式的求法。最后,在算例中,分岩体沿裂隙滑移破坏和沿岩石剪切破坏两种情况给出了裂隙岩体的峰后应力-应变曲线,讨论了裂隙的平均间距、法向刚度和剪切刚度对峰后应变的影响。结果表明,裂隙的平均间距、法向刚度和剪切刚度越小,裂隙岩体的轴向应变越大。 相似文献
12.
Rock joint modeling using a visco-plastic multilaminate model at constant normal load condition 总被引：2，自引：0，他引：2
Reza Mahin Roosta Mohammad Hossein Sadaghiani Ali Pak Yaser Saleh 《Geotechnical and Geological Engineering》2006,24(5):1449-1468
Rock joints play an important role in the behavior of rock masses under normal and shear loading conditions. Numerical simulation
of the behavior of jointed rock masses is not an easy task due to complexities involved in the problem such as joint roughness,
joint shear strength, hardening and softening phenomenon and mesh dependency. In this study for modeling purposes, a visco-plastic
multilaminate model considering hardening and softening effects has been employed. For providing the necessary data for numerical
simulation, a series of laboratory experiments have been carried out on regular tooth-shape asperities made by gypsum, under
constant normal load conditions. Shear stress–shear displacement and normal displacement–shear displacement of artificial
joint specimens are simulated using the proposed numerical model at constant normal load condition (CNL). The results indicate
the capability of the model for simulating rock joints behavior in both strength and deformation field. Although the numerical
model has been developed for simulating the behavior of artificial joints, the concept of the method can also be used for
natural rock joints. 相似文献
13.
Microplane damage model for jointed rock masses 总被引：1，自引：0，他引：1
The paper presents a new microplane constitutive model for the inelastic behavior of jointed rock masses that takes into account the mechanical behavior and geometric characteristics of cracks and joints. The basic idea is that the microplane modeling of rock masses under general triaxial loading, including compression, requires the isotropic rock matrix and the joints to be considered as two distinct phases coupled in parallel. A joint continuity factor is defined as a microplane damage variable to represent the stress‐carrying area fraction of the joint phase. Based on the assumption of parallel coupling between the rock joint and the rock matrix, the overall mechanical behavior of the rock is characterized by microplane constitutive laws for the rock matrix and for the rock joints, along with an evolution law for the microplane joint continuity factor. The inelastic response of the rock matrix and the rock joints is controlled on the microplane level by the stress–strain boundaries. Based on the arguments enunciated in developing the new microplane model M7 for concrete, the previously used volumetric–deviatoric splits of the elastic strains and of the tensile boundary are avoided. The boundaries are tensile normal, compressive normal, and shear. The numerical simulations demonstrate satisfactory fits of published triaxial test data on sandstone and on jointed plaster mortar, including quintessential features such as the strain softening and dilatancy under low confining pressure, as well as the brittle–ductile transition under higher confining pressure, and the decrease of jointed rock strength and Young's modulus with an increasing dip angle of the joint. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
14.
节理岩体的剪切贯通机制影响着边坡的稳定性。为揭示锁固段型非贯通节理岩体在不同连通率和法向应力下的破坏特征,在室内直剪试验中结合高速摄影与AE特征参数分析其剪切全过程及剪胀效应。结果表明:节理岩体直剪试验中,法向应力的增大及节理连通率的下降会致使峰值剪切应力及峰值剪切位移增大;节理连通率与法向应力对其破坏特征具显著影响,表现为节理连通率较高且法向应力较小时呈直接剪断的特性,节理连通率降低后呈拉剪复合破坏,出现剪胀现象,而法向应力的增大使得剪胀效应呈波动现象;AE特征与岩桥贯通过程一致,事件数峰值随节理连通率的降低及法向应力的增大而增大且位于峰后。试验得到的岩桥细观破坏特征与剪胀效应对研究锁固段型岩质边坡的贯通破坏机制具指导意义。 相似文献
15.
Study of rock joints under cyclic loading conditions 总被引：11，自引：3，他引：11
Summary A conceptual model for the behaviour of rock joints during cyclic shear and under constant normal stresses was proposed according to results from shear tests with 50 concrete replicas of rock joints. The shear strength and deformability of joint samples were found to be both anisotropic and stress dependent. Based on these experimental results, a two-dimensional constitutive model was developed for rock joints undergoing monotonic or cyclic loading sequences. The joint model was formulated in the framework of non-associated plasticity, coupled with empirical relations representing the surface roughness degradation, appearance of peak and residual shear stresses, different rates of dilatancy and contraction, variable normal stiffness with normal deformation, and dependence of shear strength and deformability on the normal stress. The second law of thermodynamics was represented by an inequality and used to restrict the values of some of the material parameters in the joint model. The new joint model was implemented into a two-dimensional Distinct Element Method Code, UDEC, and its predictions agreed well with some well-known test results. 相似文献
16.
New Peak Shear Strength Criterion of Rock Joints Based on Quantified Surface Description 总被引：8，自引：6，他引：2
Cai-Chu Xia Zhi-Cheng Tang Wei-Min Xiao Ying-Long Song 《Rock Mechanics and Rock Engineering》2014,47(2):387-400
The prime objective of this work is to improve our understanding of the shear behavior of rock joints. Attempts are made to relate the peak shear strength of rock joints with its three-dimensional surface morphology parameters. Three groups of tensile joint replicas with different surface morphology are tested with direct shear tests under constant normal load (CNL) conditions. Firstly, the three-dimensional surface characterization of these joints is evaluated by an improved roughness parameter before being tested. Then, a new empirical criterion is proposed for these joints expressed by three-dimensional quantified surface roughness parameters without any averaging variables in such a way that a rational dilatancy angle function is used instead of ${\text{JRC}} \cdot \log_{10} \left( {{{\text{JCS}} \mathord{\left/ {\vphantom {{\text{JCS}} {\sigma_{\text{n}} }}} \right. \kern-0em} {\sigma_{\text{n}} }}} \right)$ by satisfying the new peak dilatancy angle boundary conditions under zero and critical-state normal stress (not physical infinite normal stress). The proposed criterion has the capability of estimating the peak shear strength at the laboratory scale and the required roughness parameters can be easily measured. Finally, a comparison among the proposed criterion, Grasselli’s criterion, and Barton’s criterion are made from the perspective of both the rationality of the formula and the prediction accuracy for the three groups of joints. The limitations of Grasselli’s criterion are analyzed in detail. Another 37 experimental data points of fresh rock joints by Grasselli are used to further verify the proposed criterion. Although both the proposed criterion and Grasselli’s criterion have almost equal accuracy of predicting the peak shear strength of rock joints, the proposed criterion is easier and more intuitive from an engineering point of view because of its Mohr–Coulomb type of formulation. 相似文献