Computational homogenization of uncoupled consolidation in micro‐heterogeneous porous media

Variationally consistent homogenization is exploited for the analysis of transient uncoupled consolidation in micro‐heterogeneous porous solids, whereby the classical approach of first‐order homogenization for stationary problems is extended to transient problems. Homogenization is then carried out in the spatial domain on representative volume elements (RVE), which are introduced in quadrature points in standard fashion. Along with the classical averages, a higher‐order conservation quantity is obtained. An iterative FE²‐algorithm is devised for the case of nonlinear permeability and storage coefficients, and it is applied to pore pressure changes in asphalt‐concrete (particle composite). Various parametric studies are carried out, in particular, with respect to the influence of the ‘substructure length scale’ that is represented by the size of the RVE's. Copyright © 2009 John Wiley & Sons, Ltd.     

岩浆包裹体化学成分研究

岩浆包裹体化学成分研究难度较大,为了获得可信的数据,应当注意:1.非演化型岩浆包裹体的化学成分可以代表其初始成分。演化型岩浆包裹体应先均一、淬火后再行测定。2.均一演化型岩浆包裹体应严格遵守加热规则,否则过热作用会使包裹体壁部分熔化,造成淬火后所测包裹体成分与其真正的初始成分并不相当。3.实测资料证明,“边界层效应”对于岩浆包裹体化学成分影响微不足道。4.岩浆包裹体的化学成分只能代表其主矿物结晶时周围岩浆的成分,即仅相当于岩浆液相线上的一个点。5。把显微冷热台测温、激光喇曼探针和电子探针分析技术结合使用,对查明单个包裹体中挥发组分的性状和浓度具有很大的潜力和前途。     

巴黎大都市区商业的发展及其新近的变化

阐述了近二十年来巴黎大都市区商业所经历的巨大增长和迅速变化。     

基于有机包裹体研究追索海拉尔盆地煤成油

有机包裹体在油气成因，运移研究中具有重要的意义，本文通过对海拉尔盆地砂岩样品中的有机包裹体进行显微荧光观察，包裹体均一测温，并对包裹体成分进行轻烃气相色谱及碳同位素分析，索了研究区油气的成因性质及油气运移期次,结果表明，海拉尔地区存在煤成油，并有两期以上的油气运移。     

槽隆与台向斜构造对比的流体包裹体研究

对槽隆与台向斜这两个不同构造单元的早古生代沉积地层进行了系统的流体包裹体对比研究,阐述了其各自的流体包裹体类型,测定了均一温度,进而探讨了流体包裹体特征所显示的两大构造单元的古地理环境。     

流体包裹体在建立四川盆地古地温剖面研究中的应用

根据四川盆地沉积－埋藏史、主要地热事件、井下Ｒ０部面及钻井测温资料的综合分析,应用流体包裹体均一温度资料推算了四川盆地中部各地质时期地层的古地温,并建立了古地温梯度表,用此表可计算四川盆地各地期地层古地温。根据包裹体均一温度确定的古地温表明：四川盆地地层地温梯度由古至今逐渐降低,现今地温状况对古地温状况有明显的继承性。东吴运动（地裂运动）峨嵋山玄武岩大规模喷溢时期是盆地地温梯度最高时期,推算其地温     

Flow Simulations To Evaluate Upscaling of Permeability

We study upscaling of the permeability for porous media flow on a grid with one million blocks. The purpose is to illustrate how flow simulations can be used to evaluate upscaling methods.     

福建两个块状硫化物矿床中磁黄铁矿结构的研究

福建大田前锋梅仙块状硫化物矿床中六方磁黄铁矿中的单斜磁黄铁矿有两种交生态：受结晶方位控制的叶片状交生和受颗粒边界、裂隙控制的不规则状交生。着重由六方磁黄铁矿在冷却过程中出溶形成,而后者则是单斜磁黄铁矿交代六方磁黄铁矿的结果。叶片状交生体经历后期变形、变质后产生粗化和均一化,形成了楔形边、箱形、得杂叶片等结构。单斜磁黄铁矿在变形较弱的矿区保存较好,而在强烈部位消失殆尽,说明应力对磁黄铁矿的均一化效应     

Elasto‐plastic analysis of block structures through a homogenization method

The paper describes the development and numerical implementation of a constitutive relationship for modeling the elasto‐plastic behavior of block structures with periodic texture, regarded at a macroscopic scale as homogenized anisotropic media. The macroscopic model is shown to retain memory of the mechanical characteristics of the joints and of the shape of the blocks. The overall mechanical properties display anisotropy and singularities in the yield surface, arising from the discrete nature of the block structure and the geometrical arrangement of the units. The model is formulated in the framework of multi‐surface plasticity. It is implemented in an finite element (FE) code by means of two different algorithms: an implicit return mapping scheme and a minimization algorithm directly derived from the Haar–Karman principle. The model is validated against analytical and experimental results: the comparison between the homogenized continuum and the original block assembly shows a good agreement in terms of ultimate inelastic behavior, when the size of the block is small as compared with that of the whole assembly. Copyright © 2009 John Wiley & Sons, Ltd.     

Homogenization‐based analysis of anisotropic damage in brittle materials with unilateral effect and interactions between microcracks

This paper is devoted to micromechanical modeling of induced anisotropic damage in brittle geomaterials. The formulation of the model is based on a proper homogenization procedure by taking into account unilateral effects and interactions between microcracks. The homogenization procedure is developed in the framework of Eshelby's inclusion solution and Ponte‐Castaneda and Willis (J. Mech. Phys. Solids 1995; 43 :1919–1951) estimate. The homogenization technique is combined with the thermodynamics framework at microscopic level for the determination of damage evolution law. A rigorous crack opening–closure transition condition is established and an energy‐release‐rate‐based damage criterion is proposed. Computational aspects on the implementation of micromechanical model are also discussed. The proposed model is evaluated by comparing numerical predictions with experimental data for various laboratory tests on concrete. Parametric studies on unilateral effects and influences of microcracks interactions are finally performed and analyzed. Copyright © 2008 John Wiley & Sons, Ltd.