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采用随机四参数法对非均质砂质砾岩孔隙结构进行重构, 基于改进的SC-LBM(Shan-Chen格子玻尔兹曼)模型研究润湿流体在多孔介质中的渗吸行为。结果表明: 初始阶段的界面动力学与孔隙骨架的排列有很大关系, 会形成以基质为主的渗吸界面; 流体流经孔喉部分时, 流动断面瞬间缩小, 导致压力梯度和流动阻力迅速增加, 孔吼压力的存在导致流动断面瞬间缩小, 提高了流动阻力, 说明孔隙半径变化对渗吸速率影响较大; 后期阶段, 润湿流体会形成优势渗吸通道, 降低了波及面积, 大幅度降低了渗吸驱油速率。研究结果有助于理解流体在非均质孔隙中的自发渗吸规律, 对发挥裂缝性致密油藏渗吸驱油作用具有重要意义。 相似文献
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循环载荷下砂质土的本构模型 总被引:6,自引:0,他引:6
提出了一个描述砂质土循环载荷条件下主要特性的本构模型,并且采用不同围压下多种加载途径的土力学实验确定了模型中的待定材料常数,由本构模型的增量工数值积分计算所得到的理论曲线与不同应力路径下实验曲线十分接近,经实验验证这种本构模型能广泛地应用土工问题的弹-塑性有限元分析中。 相似文献
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M. E. Böttcher A. Rusch T. Höpner H.-J. Brumsack 《Isotopes in environmental and health studies》2013,49(1-2):109-129
Abstract Anoxic sediment surfaces coloured black by iron monosulfides (“black spots”) evolve in tidal sandflats of the Wadden Sea (southern North Sea) as a result of the degradation of buried organic matter. To follow the short- and long-term effects of organic matter burial on pore water and sediment isotopic biogeochemistry, formation of artificial black spots was initiated on the Groninger Plate (site RP63) in the backbarrier tidal flats of Spiekeroog island. Changes in concentrations (DOC, TA, TOC, sulfate, sulfide, TRS, Fe) and isotopic compositions (sulfate, sulfide, TRS, pyrite, TOC) were followed for up to 12 months and compared to reference areas. 13°C ratios of TOC clearly mirror the early diagenetic degradation of organic matter. At least temporarily closed system sulfate reduction is inferred for the artificial black spot from the variation of sulfate concentrations and stable sulfur isotope partitioning, In the interstitial waters of the black spot, 34S/32S values of coexisting dissolved sulfate and sulfide yield fractionation degrees between ?5 and ?25%. On the reference area, 34S/32S are fractionated by ?32 to ?42% as calculated from the isotope composition of solid phase reduced sulfur and pore water sulfate. Sulfur isotope fractionation seems to increase with decreasing sulfate reduction rate. Limiting factor seems to be the availability of DOC. Between the pyrite pool and the dissolved sulfide in the black spot, no significant isotope exchange is observed within 12 months. 相似文献
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Ⅰ型断裂韧度是岩石的主要特征力学参数,且影响因素很多。目前,国内可查的细观层理对岩石Ⅰ型断裂韧度影响的相关研究较少。试验利用隧道开挖中的变质砂板岩,测试了横向、纵向和无细观层理砂板岩纵波波速,并采用三点弯曲圆梁方法研究了相应砂板岩试件的Ⅰ型断裂力学性质。试验表明KIC、断裂破坏挠度、细观层理和纵波波速间存在相关关系,根据试验成果提出各向异性系数Y的概念,利用各向异性系数Y计算的K’IC值与实测的相应试件KIC符合较好。 相似文献
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A series of triaxial compression tests was carried out on a frozen sandy soil under confining pressures of 0–18 MPa at −6 °C. The experimental results indicate that, the strength of frozen sandy soil increases versus the increase in the confining pressures when σ3 ? 3 MPa, but decreases when σ3 > 3 MPa. This phenomenon is called the strengthening and weakening effects of confining pressures. A yield function, considering both effects, is proposed using the experimental method according to Drucker’s postulate, and the mathematical expression of the hardening parameter, which can describe the softening and hardening phenomenon, is provided. An elasto-plastic constitutive model for frozen sandy soil is developed. Based on the continuum damage theory, the cross anisotropic damage variables are deduced and their change regularities are investigated. Then the elasto-plastic damage constitutive model is proposed by introducing damage variables into elasto-plastic constitutive model. The validity of the model is verified by comparing its modeling results with experimental results obtained from triaxial tests. It is found that, this model can predict the deformation regularity of frozen soil exactly. It can simulate the stress–strain process under high confining pressures when pressure melting phenomena appear especially well. 相似文献
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重庆涪陵五中滑坡(130×104m3)发生于2008年1月3日,该滑坡位于涪陵五中西南的迎宾大道内侧,属单斜顺层岩质滑坡。通过详细的现场调查和室内资料分析后认为:中倾坡外的顺层结构、碎裂结构的岩体为滑坡的孕育和发生提供了物质基础和结构条件,是滑坡发生的结构性因素;泥质砂岩和泥岩属中等膨胀性岩石,遇水极易软化,加之历史上构造应力的作用,形成层间泥化夹层,泥化夹层含膨胀性粘土矿物蒙脱石和伊利石,是造成滑坡发生的控制性因素。诱发因素主要有两个:一是由于水的作用,坡体岩层间泥化夹层发生软化,降低了力学强度;二是修建公路开挖坡脚进行人工切坡形成有效临空面,坡体具备了临空剪出的条件。随着坡体的蠕动变形,在各种因素的综合作用下,层间剪切带逐渐贯通,最终导致滑坡发生。 相似文献