共查询到19条相似文献，搜索用时 281 毫秒
1.
三峡库区广泛分布侏罗系红砂岩, 在水库运行期间红砂岩的渗流-应力耦合特性关乎库区内多数滑坡和岩质边坡的稳定性。借助岩石多场耦合三轴试验系统, 对三峡库区侏罗系红砂岩开展了不同围压、不同渗透压下的三轴压缩试验, 系统研究了红砂岩的三轴压缩力学特性和渗透率演化特征。研究结果表明: ①红砂岩的峰前应力-应变曲线可分为孔隙压密阶段、弹性变形阶段、微裂隙稳定发展阶段和非稳定发展阶段。红砂岩的力学参数与渗透压的关系呈负相关, 与围压呈正相关。②随着围压升高, 红砂岩的破坏模式由张拉破坏过渡到剪切破坏。③不同渗透压下, 渗透率曲线呈平稳发展→缓慢上升→快速上升3阶段演化规律; 不同围压下, 渗透率曲线先降低后升高。④从能量角度分析了渗透压和围压对岩石的作用, 验证了渗流对岩石的劣化效应以及围压对裂纹发展的抑制作用。本试验对鲜有报道的侏罗系红砂岩的强度、变形和渗透特性做了系统的研究, 对渗流-应力耦合课题有补充意义。其工况根据三峡库区边坡岩体的应力水平来确定, 试验结果对分析库区边坡稳定性具有指导意义。 相似文献
2.
为对后续套管损坏力学研究提供新的研究方向,提出一种运用孔隙变化作为细观损伤变量描述泥岩蠕变变形特征,确立宏观损伤变量与细观损伤变量本质关系,并建立基于细观损伤变量的泥岩蠕变损伤本构模型.选取长庆油田石盒子组泥岩岩样作为工程实例,得出泥岩蠕变损伤岩体理论应力与应变本构关系,理论计算应力和实验测定应力相比,最大误差为9.2... 相似文献
3.
层状反倾岩质边坡是一种常见边坡类型，其变形破坏模式多样、力学机制复杂、影响因素众多。为揭示层状反倾岩质边坡不同临空条件几何特征参数对反倾边坡倾倒变形影响规律，通过3DEC并结合数理统计系统深入研究几何特征参数对倾倒变形影响。研究表明:①反倾边坡具有3个临空面时边坡变形最大，1个临空面时边坡变形最小；②变形随边坡高度、切坡角度增大而增大，随节理面与临空面夹角的增大而减小，随岩层厚度增大先增大后减小；③2个临空面夹角90°时边坡变形最大；④1个、2个临空面时节理倾角60°时位移最大，3个临空面时随节理倾角增大而增大。 相似文献
4.
为研究反倾岩质边坡的变形破坏规律性与形成机制,以黄河上游茨哈峡水电站库区反倾岩质边坡变形破坏为例,基于系统的工程地质方法并结合离散元模拟边坡的变形演化进程,对其倾倒变形的时效性进行了分析并研究了其形成演化机制。结果表明:①该倾倒边坡的时效变形规律表现为倾倒变形在不同方向上具有差异性,其时空演化特征表现为斜坡顶部的拉裂和中部的弯曲变形,目前倾倒体内未形成贯通性失稳界面,倾倒拉裂和弯曲变形同时存在,表现为倾倒机制的长期性、积累性和阶段性;②该类斜坡的变形破坏是岩层在自重应力作用下做悬臂梁弯曲,岩层发生弯曲变形,导致坡体后缘开裂、根部折断、前缘剪切蠕变,当坡体折断带内的剪应力超过其抗剪强度时,坡体逐渐错动下滑形成倾倒塌滑体;③该倾倒变形体的破坏模式为弯曲—拉裂变形、弯曲—折断破裂、蠕滑—拉裂变形、表层滑塌和深部滑坡形成。 相似文献
5.
边坡条分法物理意义是以强度折减表征材料峰值强度的下降程度。以不平衡推力部分强度折减法为例,推广传统假设,应用理想弹塑性模型和全过程剪应力-应变模型,在峰值剪应力和峰值应变相等条件下,模拟边坡的渐进破坏过程;提出了临界状态决定法,随着临界状态逐步移动,边坡不平衡力和驱动力越来越大,抗滑力越来越小,直至整体处于破坏状态。以湖北省恩施州稻池村边坡为例,以3种数值(部分强度折减、理想弹塑性和全过程剪应力-应变本构)模型揭示边坡渐进破坏过程中各参量变化特征。结果表明:3种数值条块法均能描述稻池村边坡渐进破坏过程,基于条分法和理想弹塑性模型部分强度折减系数大于全过程剪应力-应变本构模型稳定系数。 相似文献
6.
寒区岩石的力学特征往往受到冻融循环和荷载的共同影响,冻融岩石单轴压缩破坏断口蕴含着与冻融循环和荷载有关的损伤演化信息,冻融岩石单轴压缩破坏断口研究对冻融岩石断裂破坏机理分析有重要价值。为研究冻融岩石单轴压缩破坏断口形貌特征及其与宏观力学参数之间的关联性,通过摄影观测经历不同次数冻融循环的砂岩单轴压缩破坏断口形貌,采用像素点覆盖法计算断口分维值,探究了断口分维值与宏观力学参数之间的关系。结果表明:随着冻融次数的增加,冻融砂岩的力学性能劣化,单轴抗压强度、弹性模量、断口分维值、耗散能密度逐渐减小,峰值应变增大;单轴抗压强度、弹性模量、耗散能密度均与断口分维值之间存在指数关系,断口分维值越大,对应的单轴抗压强度、弹性模量、耗散能密度越大。冻融岩石单轴压缩破坏断口分维值可作为寒区岩体断裂破坏机理分析的有效参数。 相似文献
7.
根据高应力区砂岩三轴压缩试验和峰前卸围压试验的结果,分析了砂岩在不同应力路径下的能量变化规律。试验结果表明,相同围压下,峰前卸围压试验的各能量指标(总吸收能、弹性应变能、耗散能)均小于三轴压缩试验,能量变化特征与其初始应力路径密切相关,且随围压的增大而增大。峰前储存的弹性应变能比耗散能多,耗散能只在临近峰值点处才迅速增加。能量的耗散会导致岩石产生损伤,并且使岩性劣化、丧失强度,从能量角度定义的损伤变量,可以得出结论:开始卸荷低围压下的损伤变量大于高围压下,临近破坏时高围压下的损伤变量大于低围压下;卸围压使岩样束缚减小,加速了损伤的发展,岩样所受的应力状态愈趋不平衡。因此,基于能量的角度来表征岩石的损伤演化更符合实际。 相似文献
8.
岩石蠕变特性对岩体工程的长期稳定有着重要影响, 尤其是在酸雨等水化学作用下, 岩石的细观结构遭到破坏, 蠕变特性及变形更为显著。以重庆二佛寺红层砂岩为研究对象, 通过开展室内三轴压缩分级蠕变试验, 研究了酸腐蚀状态下砂岩的蠕变特性。结果表明: 酸的腐蚀和浸泡会使砂岩内部孔隙增加, 导致砂岩在第一级荷载下会产生较大的瞬时应变和蠕变量, 之后瞬时应变量和蠕变量随着应力增加而增大; 岩样受到腐蚀软化, 蠕变破坏强度为抗压强度的76%, 长期强度仅为抗压强度的54%。为了描述蠕变全过程, 建立了一个损伤蠕变模型来拟合试验数据, 验证了其适用性, 可以为岩土工程建设的稳定性提供参考。 相似文献
9.
三向应力及湿度状态改变对非饱和黄土力学特征的影响 总被引：6，自引：0，他引：6
通过对黄土常规三轴试验结果分析,给出了非饱和黄土的强度参数随含水量的指数型变化关系式,并验证了D-P屈服准则对不同湿度状态下黄土发生塑性屈服的适用性。不同三向应力条件和温度状态下的压缩试验表明,Q3黄土的应力应变关系随着三向应力和含水量而变化,这种本构关系可以用一个简单的指数函数来描述。与已有的模型相比,基于室内试验提出的半经验型黄土本构关系具有模型简单、参数少、易确定的优点。 相似文献
10.
在理论分析的基础上,利用试验结果模拟分析单轴压力作用下含裂隙恐龙化石断裂损伤过程。在FLAC3D中采用FISH语言编写了基于体元分析的计算程序,采用弹脆性本构模型,分析了试验过程中恐龙化石的裂纹萌生→扩展→贯通规律和裂隙化石的断裂损伤机制。在单轴压缩作用下,含有裂隙的恐龙化石试件的破坏过程主要分三个阶段:即线性变形阶段、非线性变形阶段和软化阶段,当载荷超过应变峰值强度后,化石内部将生成大量新的诱导裂隙,导致化石内部结构发生剧烈变化。值得注意的是,恐龙化石峰后的强度软化过程非常不稳定,峰值附近的材料力学行为对化石试件内部缺陷的分布十分敏感。试验表明,有裂隙恐龙化石的抗压强度值比无裂隙恐龙化石的抗压强度值小30%,最终的残余抗压强度也略小,在加载应力作用下,相比不含内部裂隙的恐龙化石,内含裂隙的恐龙化石其内部裂隙会迅速大量扩展,加重了恐龙化石的风化程度和破坏速度。 相似文献
11.
Effect of the inclined weak interlayers on the rainfall response of a bedded rock slope 总被引：1，自引：1，他引：0
Engineering experience shows that outward dipping bedded rock slopes, especially including weak interlayers, are prone to slide under rainfall conditions. To investigate the effect of inclined weak interlayers at various levels of depth below the surface on the variation of displacements and stresses in bedded rock slopes, four geo-mechanical model tests with artificial rainfall have been conducted. Displacements, water content as well as earth pressure in the model were monitored by means of various FBG (Fiber Bragg Grating) sensors. The results showed that the amount of displacement of a slope with a weak interlayer is 2.8 to 6.2 times larger than that of a slope without a weak interlayer during one rainfall event. Furthermore, the position of the weak interlayer in terms of depth below the surface has a significant effect on the zone of deformation in the model. In the slope with a high position weak interlayer, the recorded deformation was larger in the superficial layer of the model and smaller in the frontal portion than in the slope with a low position weak interlayer. The slope with two weak interlayers has the largest deformation at all locations of all test slopes. The slope without a weak interlayer was only saturated in its superficial layer, while the displacement decreased with depth. That was different from all slopes with a weak interlayer in which the largest displacement shifted from the superficial layer to the weak interlayer when rainfall persisted. Plastic deformation of the weak interlayer promoted the formation of cracks which caused more water to flow into the slope, thus causing larger deformation in the slope with weak interlayers. In addition, the slide thrust pressure showed a vibration phenomenon 0.5 to 1 hour ahead of an abrupt increase of the deformation, which was interpreted as a predictor for rainfall-induced failure of bedded rock slopes. 相似文献
12.
The dynamic failure mode and energy-based identification method for a counter-bedding rock slope with weak intercalated layers are discussed in this paper using large scale shaking table test and the Hilbert-Huang Transform (HHT) marginal spectrum. The results show that variations in the peak values of marginal spectra can clearly indicate the process of dynamic damage development inside the model slope. The identification results of marginal spectra closely coincide with the monitoring results of slope face displacement in the test. When subjected to the earthquake excitation with 0.1 g and 0.2 g amplitudes, no seismic damage is observed in the model slope, while the peak values of marginal spectra increase linearly with increasing slope height. In the case of 0.3 g seismic excitation, dynamic damage occurs near the slope crest and some rock blocks fall off the slope crest. When the seismic excitation reaches 0.4 g, the dynamic damage inside the model slope extends to the part with relative height of 0.295-0.6, and minor horizontal cracks occur in the middle part of the model slope. When the seismic excitation reaches 0.6 g, the damage further extends to the slope toe, and the damage inside the model slope extends to the part with relative height below 0.295, and the upper part (near the relative height of 0.8) slides outwards. Longitudinal fissures appear in the slope face, which connect with horizontal cracks, the weak intercalated layers at middle slope height are extruded out and the slope crest breaks up. The marginal spectrum identification results demonstrate that the dynamic damage near the slope face is minor as compared with that inside the model slope. The dynamic failure mode of counter-bedding rock slope with weak intercalated layers is extrusion and sliding at the middle rock strata. The research results of this paper are meaningful for the further understanding of the dynamic failure mode of counter-bedding rock slope with weak intercalated layers. 相似文献
13.
采用有限元软件ABAQUS建立含不同裂缝工况的压电-混凝土梁机电耦合模型,通过安装在混凝土梁设定位置的压电激励器输入激励信号并实时采集反馈信号,计算应力波信号值与小波包能量值,分析信号值和能量与损伤工况间的内在关系。结果表明,在混凝土梁跨中垂直裂缝和支座处斜裂缝工况下,压电应力波的信号值随裂缝深度的增加而减小;裂缝宽度增至2~3 mm时信号值会有所减小,随后裂缝宽度增加对其影响不再明显。当在裂缝演化方向上的深度达到梁体纵向中心轴高度时,应力波接收信号衰减明显。将信号相对能量值作为损伤程度因子,有利于分析应力波在病损混凝土内部的传播与衰减机理,能有效检测混凝土裂缝损伤程度。 相似文献
14.
岩体变形和破坏可以看作能量耗散和释放的过程.由于节理岩体结构复杂且难以开展室内试验,因此无法通过试验直接求取其能量学参数.基于Hoek-Brown准则和岩石能量理论,提出了节理岩体在临界状态能量学参数的估算方法.针对含贯通节理(或层面)岩体,通过修正岩块单轴抗压强度以体现贯通节理的方向效应.采用PFC3D分别模拟小尺寸岩样(Φ50mm×100mm)和大尺寸岩体(Φ2m×2m)的三轴压缩试验,通过岩石三轴试验结果拟合岩石数值模拟的细观参数并应用于节理岩体的模拟.根据节理岩体模拟得到应力应变曲线和能量流,验证了Hoek-Brown准则对节理岩体能量参数估算的合理性. 相似文献
15.
Effect of Freeze-Thaw Cycles on Mechanical Properties and Permeability of Red Sandstone under Triaxial Compression 总被引：1，自引：1，他引：0
Geological disasters will happen in cold regions because of the effects of freeze-thaw cycles on rocks or soils, so studying the effects of these cycles on the mechanical characteristics and permeability properties of rocks is very important. In this study,red sandstone samples were frozen and thawed with 0,4, 8 and 12 cycles, each cycle including 12 h of freezing and 12 h of thawing. The P-wave velocities of these samples were measured, and the mechanical properties and evolution of the steady-state permeabilities were investigated in a series of uniaxial and triaxial compression tests. Experimental results show that, with the increasing of cyclic freeze-thaw times, the P-wave velocity of the red sandstone decreases. The number of freeze-thaw cycles has a significant influence on the uniaxial compressive strength, elastic modulus, cohesion, and angle of internal friction. The evolution of permeability of the rock samples after cycles of freeze-thaw in a complete stress-strain process under triaxial compression is closely related to the variation of the microstructure in the rock. There is a highly corresponding relationship between volumetric strain and permeability with axial strain in all stages of the stress-strain behaviour. 相似文献
16.
《山地科学学报》2021,(8)
Tibetan Plateau is known as the roof of the world. Due to the continuous uplift of the Tibetan Plateau, many active fault zones are present. These active fault zones such as the Anninghe fault zone have a significant influence on the formation of special geomorphology and the distribution of geological hazards at the eastern edge of the Tibetan Plateau. The Anninghe fault zone is a key part of the Y-shaped fault pattern in the Sichuan-Yunnan block of China. In this paper, high-resolution topographic data, multitemporal remote sensing images, numerical calculations, seismic records, and comprehensive field investigations were employed to study the landslide distribution along the active part of the Anninghe. The influence of active faults on the lithology, rock mass structures and slope stress fields were also studied. The results show that the faults within the Anninghe fault zone have damaged the structure and integrity of the slope rock mass, reduced the mechanical strength of the rock mass and controlled the slope failure modes. The faults have also controlled the stress field, the distribution of the plastic strain zone and the maximum shear strain zone of the slope, thus have promoted the formation and evolution of landslides. We find that the studied landslides are linearly distributed along the Anninghe fault zone, and more than 80% of these landslides are within 2-3 km of the fault rupture zone. Moreover, the Anninghe fault zone provides abundant substance for landslides or debris flows. This paper presents four types of sliding mode control of the Anninghe fault zone, e.g., constituting the whole landslide body, controlling the lateral boundary of the landslide, controlling the crown of the landslide, and constituting the toe of the landslide. The results presented merit close attention as a valuable reference source for local infrastructure planning and engineering projects. 相似文献
17.
缅甸安达曼海弧后坳陷天然气成藏要素及成藏模式 总被引：1，自引：0，他引：1
缅甸安达曼海已成为中国石油企业的重要海外探区之一。受印度板块向欧亚板块和西缅甸微地块多期斜向俯冲的影响,该区先后经历了被动陆缘、过渡型陆缘及主动陆缘的演化阶段,盆地属性与油气成藏特征极为复杂。通过系统梳理安达曼海弧后坳陷的烃源岩、储盖层、圈闭、输导体系与油气生-运-聚匹配史等成藏要素,总结出该区油气成藏主控因素。结果表明:本区发育渐新统—下中新统、中中新统与上新统3套泥质烃源岩,前二者为成熟烃源岩,后者为生物气源岩;岛弧带上碳酸盐岩礁体与斜坡带上砂体的储集条件良好;斜坡带继承性古隆起之上的断背斜圈闭容积大;高角度张性断裂与连通性砂体分别构成以垂向、侧向为主的输导体系。结合油气成因、运移方式与圈闭类型的主要特征,建立了2种成藏模式:①中央凹陷带浅层生物气或混源气垂向运移断块圈闭成藏模式;②东部斜坡带、西部斜坡和岛弧带热解气侧向运移断背斜-岩性圈闭成藏模式。西部斜坡及岛弧带上的碳酸盐岩礁体和东部斜坡带继承性古隆起之上的大型断背斜是有利勘探目标。 相似文献
18.
Gently dipping fractures subjected to river incision are widely distributed on rock slopes. In this paper, a rock slope on the Nujiang River (China) is investigated to study the role of gently dipping fractures in the rock slopes evolution. Detailed field surveys indicate that gentle fractures are concentrated in four main zones. Moreover, the kinematics of the fracture system suggest that the genesis of these fractures can be synthesized into a progressive evolution model. This model indicates that the joints begin with the formation of an array of en echelon cracks that are subjected to continued crack elongation and shearing before ultimately approaching one another and interacting to form a complex joint system. Geomechanical analysis is performed to reveal the mechanisms of this genesis, and three main fracture patterns are identified based on the slope stress and are classified with respect to the slope evolution. Based on the detail field investigations and the evolutionary history of the river valley, we propose that intermittent incision by the river was the main factor contributing to the concentrated distribution of gently dipping joints. 相似文献
19.
《山地科学学报》2021,(5)
Large squeezing deformation of layered soft rock tunnel under high geo-stress has a significant time-dependent deformation behavior. In this paper, we studied the deformation mechanism during the construction period of deep-buried softrock tunnel by means of a combination of field observations and a numerical method. First, a new classification criterion for large deformations based on the power exponent variation law between the deformation and the strength-stress ratio is proposed. Then, the initial damage tensor reflecting the bedding plane(joint) distribution and an equivalent damage evolution equation derived from the viscoplastic strain are introduced based on the geometric research method, i.e., a new rheological damage model(RDL model) of layered soft rock is established consisting of elastic, viscous, viscoelastic, viscoplastic and plastic elements. A field test was conducted on the Maoxian tunnel in Sichuan province, southwestern China, which is in broken phyllite(layered soft rock) under high geo-stress. The tunnel has experienced large deformation due to serious squeezing pressure, thus we adopted double primary support method to overcome the supporting structure failure problems. The rheological parameters of phyllite in the Maoxian tunnel were recognized by using SA-PSO optimization, and the RDL model does a good job in describing the time-dependent deformation behavior of a layered soft-rock tunnel under high geo-stress. Thus, the RDL model was used to investigate the supporting effect and bearing mechanism of the double primary support method. Compared with the single primary support method, the surrounding rock pressure, secondary lining force, surrounding rock deformation, and the depth of the damage to the rock mass was reduced by 40%-60% after the double primary support method was used. 相似文献