考虑指数流的真空预压竖井地基固结解析解

传统固结理论认为渗流速度和水力梯度呈线性关系,但在软塑性土地基中常出现背离线性关系的情况,即为非达西渗流模式。在经典竖井地基固结理论的基础上,假设孔隙水渗透服从指数渗流模式,并结合真空预压的边界条件,建立新的竖井地基固结计算模型,获得超静孔压和径向固结度的严格解答,并通过开展多工况算例对比,分析指数渗流模型参数和真空压力沿竖井衰减系数等对竖井地基固结计算结果的影响效应。研究结果表明:非达西渗流指数m对固结速率影响最为显著,在固结初期,m越大,固结速率越快;在固结后期,m越小,固结速率越快;涂抹区参数s及κh/κs越大,竖井地基固结速率越慢;负压衰减系数k1和k2、真空荷载p0越大,固结速率越快。     

考虑非达西渗流的结构性软土非线性固结分析

在传统太沙基一维固结理论基础上,引入经典的Hansbo非达西渗流模型,考虑天然土体结构性对固结的影响,建立实际变荷载作用下土体的非线性固结模型,并利用有限差分法求取模型的数值解.在保证数值解可靠性的基础上,分析非达西渗流对结构性软土固结性状的影响及非达西渗流下土体结构性对固结性状的影响.结果表明:非达西渗流下结构性软土的固结速率要比达西定律下慢,且随非达西渗流模型参数m和i1的增大,固结速率的减小愈加明显;对考虑非达西渗流的结构性软土而言,结构屈服应力越大,结构屈服应力前土的压缩指数越小,则结构性软土的固结速率越大,地基土的最终沉降值越小.     

基于非达西渗流的砂井地基径向固结解

采用考虑起始水力梯度的非达西渗流模型,修正了砂并地基固结理论.建立了相应的控制方程,并对其求解,给出了便于应用的显式解答,在此基础上研究了考虑起始水力梯度时砂井地基的固结性状.结果表明,由于起始水力梯度的存在,应力固结度最终将稳定在一个小于100％的数值上,最终的固结度随着起始水力梯度增大而减小.初始孔压也会对固结性状产生影响,初始孔压越大,孔压消散越充分,最终达到的应力固结度越大.但是初始孔压增大到一定值之后,最终固结度对其灵敏度降低.     

基于非达西渗流的砂井地基固结解

采用考虑起始水力梯度的非达西渗流模型,修正了砂井地基固结理论.建立了相应的控制方程,并对其求解,给出了便于应用的显式解答,在此基础上研究了考虑起始水力梯度时砂井地基的固结性状.结果表明,由于起始水力梯度的存在,应力固结度最终将稳定在一个小于100%的数值上,最终的固结度随着起始水力梯度增大而减小.初始孔压也会对固结性状产生影响,初始孔压越大,孔压消散越充分,最终达到的应力固结度越大.但是初始孔压增大到一定值之后,最终固结度对其灵敏度降低.     

指数形式渗流定律下软土一维大变形固结分析

在土中渗流遵循指数形式渗流定律下,假定土体压缩系数和渗透系数在固结过程中均保持不变,在拉格朗日坐标系下,以超静孔隙水压力为变量,建立软土一维大变形固结问题的控制方程及求解条件.利用有限差分法,对计算模型进行求解,得到超静孔隙水压力的数值解答.在此基础上,对某时刻不同深度处土体孔隙比以及地基沉降变形进行求解,并据此给出按变形定义的地基平均固结度和按应力定义的地基平均固结度的解答.最后,结合实例分析了渗流指数对大变形固结性状的影响,分析了基于指数形式渗流定律的软土一维大、小变形固结理论的区别,给出了基于指数形式渗流定律的软土一维固结问题中必须要考虑大变形特性的条件.     

基于指数形式渗流下的软土一维非线性固结分析

已有的室内试验资料表明软黏土中的渗流会遵循指数形式渗流定律,并且土体压缩性、渗透性在固结过程中会表现出明显的非线性特性。在土中自重应力沿深度均匀分布的假定下,推导建立基于指数形式渗流的软土一维非线性固结控制微分方程,并利用有限差分法对其进行数值求解。将数值解与达西渗流下Davis解析解进行对比,验证数值计算结果的可靠性。最后,对基于指数形式渗流下的一维非线性固结性状进行分析。研究结果表明:土层的固结速率在固结初期随渗流指数的增大而加快;而当时间因子超过某一值后,在固结后期固结速率随渗流指数的增加而变慢;土的压缩指数与渗透指数的比值越大,则土层的固结速率越慢;此外,土层中最终有效应力与初始有效应力的比值以及外荷载的等效水头与土层厚度的比值均对固结速率有较大影响。     

初始孔压非均布的饱和土一维热固结解析解

基于热弹性力学和饱和土固结理论,通过热固结方程的建立和求解,研究了初始孔压非均布时的饱和土一维热固结问题.利用有限Fourier变换及其逆变换,得到土层内部超静孔压、温度增量的解析解,并依此求出地基沉降、平均固结度的表达式.根据所得解编制计算程序,分析了饱和土的一维热固结性状,并与不考虑温度影响的传统固结解进行比较.结果表明,超静孔压随时间延长最终消散为零,但在热固结过程中可能会产生负孔压;地基沉降受温度升高的影响小于传统固结解;平均固结度按沉降定义和按孔压定义是不同的,其变化规律与传统的固结理论有较大差别.     

基于双对数压缩模型的真空预压非线性固结解

考虑真空荷载实际边界条件,引入对土体压缩曲线线性化的双对数坐标,建立了真空预压砂井地基非线性固结近似解答;利用模型试验结果验证了解答的可靠性,并分析了真空度衰减和土性参数对固结性状的影响.研究结果表明,考虑了真空荷载衰减及双对数坐标的解答计算得到的土体沉降、超静孔压与实测值最为接近.对于超固结土而言,基于变形计算的固结度随着压缩指数与渗透指数比值的增大而减小,随着真空荷载衰减系数的减小而减小;当压缩指数与渗透指数比值大于1时,正常固结状态中基于孔压计算的固结度随真空荷载衰减系数的减小而增大.随着压缩指数与回弹指数比值的增大,地基超静孔压消散速率也随之增加,沉降速率在超固结状态时随之减缓,在正常固结状态时则随之加快,土体由超固结状态进入正常固结状态的时间随之变长.     

欠固结竖井地基的大应变固结分析

基于分段线性法,对真空-堆载联合预压下竖井地基大变形非线性固结(VRCS1)模型进行简单拓展,使其能用于欠固结竖井地基的大应变固结分析.通过工程案例和数值法对比,验证了拓展方法的正确性,并通过竖井地基自重固结与加载固结的对比,表明两种类型荷载产生不同的固结过程,忽略竖井地基的欠固结会导致固结分析误差.使用VRCS1拓展模型对影响欠固结竖井地基固结的土颗粒相对密度、土体初始高度和初始孔隙比进行分析,结果表明:欠固结土的土颗粒相对密度越大,最终沉降越大,但等应力条件使整体固结沉降速率越慢;欠固结土体初始高度越大,最终沉降越大,但整体固结度发展速率越慢;土体初始孔隙比越大,最终沉降越大,固结速率也越快.     

孔隙比变量一维固结方程解析理论

经典Terzaghi固结理论假定固结沉降与超孔压消散间满足线性耦合关系,通过计算土体应力固结度与土体最终沉降量预测沉降发展过程。由于土体固结沉降与超孔压消散间存在不同步耦合效应,沉降发展快于超孔压消散,应用应力固结度预测土体沉降发展误差较大。以孔隙比变量作为固结方程控制变量,根据孔隙比边界条件求解土体固结沉降过程可以有效避开超孔压消散与土体沉降间的滞后耦合效应。以土体连续方程、达西定律、有效应力原理为基础推导孔隙比变量固结方程及边界条件,研究边界条件、土体自重、初始孔隙比分布、非瞬时加载等对土体固结过程与最终效果的影响,比较应力与应变固结度间差异。研究表明初始条件、土体自重等对孔隙比变量解答有较大影响,引起5%左右误差。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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