Application of Acoustic Wave Propagation Analysis Methods for Monitoring a Miscible Mixing Zone in Porous Media

The Biot's acoustics theory, which describes acoustic wave propagation in a porous medium, and computer simulation techniques were utilized to model the behavior of acoustic waves entering and leaving a mixing zone in a miscible displacement in porous media. The results indicate that the angles of waves produced by a mixing zone are equal to angles of waves produced by an abrupt fluid-fluid interface. Therefore, acoustic methods and a relationship between the incident, reflection, and transmission angles can be used to determine the location and thickness of the mixing zone during a miscible displacement process in porous media.     

An elliptical disc anchor in a damage‐susceptible poroelastic medium

A flat rigid elliptical anchorage located in a damage‐susceptible fluid‐saturated poroelastic medium is subjected to an in‐plane load, which induces a pure translation in the plane of the anchor. This paper develops computational estimates for the time‐dependent displacement of the disc anchor for the classical problem that involves Biot consolidation and compares the results with situations where the porous skeleton can experience micro‐mechanical damage that leads to an alteration in both its elasticity and fluid transport characteristics. Copyright © 2005 John Wiley & Sons, Ltd.     

土壤的固结效应及精细积分数值求解

基于广义Biot固结理论，利用有限元离散方法，得到土层固结效应的u-p形式的基本方程，进而通过引入基本方程中原变量的对偶变量，在Hamilton体系下建立了土层固结效应的微分方程。在具体计算过程中，利用时程精细积分方法，对固结问题进行了计算，并通过数值算例说明了中方法的有效性。     

Approximate solutions for the ignition of a solid as a function of the Biot number

The ignition of a finite planar 1‐dimensional solid is addressed for constant applied radiant heat flux. An ignition temperature criterion is used, with constant properties, and linearized reradiation. An approximate integral analysis leads to analytic formulas to predict the ignition time in terms of Biot (Bi) number and heat flux. The accuracy of the integral solution is found to be good compared to the exact infinite series solution for the conduction equation. The integral model is then used to assess the accuracy of common ideal thick and thin formulas for ignition. There is a domain of heat flux and Bi where the ideal formulas are not accurate. An example is given where the integral model is accurately applied to ignition data to illustrate the range where the ideal formula is not accurate.     

比奥模型在井点降水引起地面变形中的应用

井点降水引起的地面变形是工程施工中经常遇到的问题,80年代之后这一问题开始受到重视,由于沉降的机理复杂,目前这一问题仍然没有很好的解决。作者在分析了降水引起地面变形的机理的基础之上,即把地面变形归结于有效应力的增加,动水压力的作用,以及井点的真空作用,提出采用比奥模型进行预测,并结合南京地铁某基坑降水工程,从而为其合理的降水方案提供了依据。     

条形荷载下饱和均质地基曼德尔效应研究

本文通过研究biot固结理论,探讨了曼德尔效应产生的原因,并利用大型非线性有限元软件adina进行数值分析,得出条形荷载下饱和均质地基固结的数值解。并通过计算分析,得出了影响曼德尔效应的因素。     

Biot固结平面有限元程序网格局部加密方法研究

为了解决软土地基上的构筑物沉降过大、承载力不满足等问题 ,很多学者依据Biot固结理论编制了大量的有限元程序。要在基本相同的计算量的前题下获得足够的精度 ,需要对有限元网格进行局部加密处理。作者提出的加密方法合理解决了接触单元和多级加载问题 ,并使用C ++Builder开发工具编制了加密程序 ,最后给出一个工程实例验证了方法的可行性。     

Influences of soil hydraulic and mechanical parameters on land subsidence and ground fissures caused bygroundwater exploitation简

In order to study the influences of hydraulic and mechanical parameters on land subsidence and ground fissure caused by groundwater exploitation,based on the Biot’s consolidation theory and combined with the nonlinear rheological theory of soil,the constitutive relation in Biot’s consolidation theory is extended to include the viscoelastic plasticity,and the dynamic relationship among the porosity,the hydraulic conductivity,the parameters of soil deformation and effective stress is also considered,a threedimensional full coupling mathematical model is established and applied to the study of land subsidence and ground fissures of Cangzhou in Hebei Province,through the analysis of parameter sensitivity,the influences of soil hydraulic and mechanical parameters on land subsidence and ground fissure are revealed.It is shown that the elastic modulus E,the Poisson ratio v,the specific yield u and the soil cohesion c have a great influence on the land subsidence and the ground fissures.In addition,the vertical hydraulic conductivity z k and the horizontal hydraulic conductivity s k also have a great influence on the land subsidence and the ground fissures.     

勘察地下管线的一种新方法——同点比值法

在同一测点观测两个相互正交的磁场分量之振幅比值T。测线上T曲线某些特征值点的坐标与地下管线的水平位置和埋深有简单函数关系,且T值不受管线中电源强度不稳定的影响,从而简便、快速、准确地确定地下管线的水平位置和埋深。     

多孔介质的流体机制模型及其频散机理

当声波或弹性波在流体饱和多孔介质中传播时，孔隙或裂缝受其影响发生闭合或张开，流体产生相对运动，致使多孔隙岩石的宏观物理性质发生变化，从而引起弹性波传播速度的改变、能量的耗散和振幅的衰减。基于双相介质理论提出的Gassmann方程、Biot理论、喷流机制、BISQ模型和斑块饱和模型等岩石物理机制模型，以不同的流体流动机制描述了多孔介质中弹性波传播的动态耦合机理、耦合程度和耦合结果。许多岩石物理机制模型都试图模拟和解释岩石中速度频散和衰减的起因。根据现有各种机制模型的高限、低限频率和特征（弛豫）频率，可以粗略地计算出衰减和频散的影响。随着地震岩石物理学研究的深入与发展，人们对弹性波速度频散和衰减与岩石物理性质及本征条件之间关系的认识必将不断深化。