非饱和全空间埋置隧道动力响应半解析模型

将非饱和地基土视为由固、液、气组成的三相介质,圆形隧道衬砌简化为无限长的Flügge薄壁圆柱壳,分别采用Helmholtz矢量分解定理以及分离变量法求解非饱和地基土的波动方程和Flügge薄壁圆柱壳的振动控制方程。结合位移和应力连续性等边界条件,建立移动简谐荷载下非饱和地基土中埋置隧道动力响应的半解析模型。基于该模型,探讨了非饱和地基土-隧道系统的动力响应特征及饱和度对系统动力响应的影响。结果表明,饱和度对土体的动位移、动应力、超孔隙水压力及土体临界速度等影响较大,计算时应考虑饱和度的影响。     

饱和分层地基上列车运行引起的地面振动分析

基于薄层法原理,将圆柱坐标系下饱和土的Biot轴对称波动方程在竖向进行离散,沿切向坐标及轴向分别进行Fourier级数分解和Hankel变换,得到饱和层状介质中频域～波数域中的位移基本解表达式,再利用Hankel逆变换和Fourier综合,求得频域柱坐标系下的位移表达式。结合运行列车～轨道～地基的振动模型,对饱和分层地基上列车运行引起的地面振动进行分析。详细讨论了渗透系数、孔隙率、流体粘滞系数和剪切波速等饱和土层参数对振动传播与衰减的影响规律。研究表明：地基的第一层土体参数对列车运行引起的地面振动的影响比第二层土体参数的影响显著,饱和土体的渗透系数、孔隙流体动力粘滞系数、孔隙率和剪切波速是影响地面振动的主要参数。     

成层地基中静压单桩挤土效应试验

采用室内模型试验研究了成层地基中静压桩沉桩过程,对模型桩整个沉桩过程中的挤土效应进行了分析研究。通过模型试验对在均质不同软硬地基中静力压入单桩过程产生的位移场进行了比较分析,获得了浅层土体、桩身周围、桩端处土体不同的位移变化模式,并揭示了桩周不同位置特别是软硬土层交界处土体位移随水平和深度方向的变化规律。试验结果表明,均质地基挤土位移的最大值与压桩深度存在滞后效应;对于成层地基,最大径向、竖向位移均出现在软硬土层交界面处,由于软硬土层力学性质的差异,土体位移主要表现为,软层处位移变大,硬层处位移变小。试验获得的结果便于进一步明确静压桩沉桩过程中挤土效应的内在机理,对预估沉桩的施工影响和指导沉桩设计都具有现实意义。     

非饱和土半空间表面在垂直集中力作用下的Lamb问题

以多孔介质混合物理论为基础,同时引入土体双变量本构关系,得到了非饱和土中的一组动力控制方程。利用Hankel积分变换方法,直接对频域内的波动方程进行求解,得到了轴对称情况下土体骨架位移及应力分量在变换域内的解。在此基础上研究了非饱和土半空间体在垂直集中力作用下的动力响应,给出了Lamb问题积分形式解。当不计土中水、气的存在时,上述结果退化到单相弹性半空间中的经典Lamb解。通过数值计算分析,进一步研究了各物理参数对地基动力响应的影响规律。     

2.5维有限元分析高铁荷载诱发非饱和土地面振动

开发一种非饱和地基2.5维有限单元方法研究高速列车荷载引起的地面振动.对时间进行Fourier变换并沿轨道方向进行波数变换将三维空间问题降为二维平面问题,结合边界条件和Galerkin法推导控制方程2.5维有限元格式.轨道结构视为非饱和地基上的Euler梁,所得频域-波数域内解答通过快速Fourier逆变换得到三维时域-空间域内结果.分析了车速和路基液体饱和度对地面振动及超静孔隙水压力的影响.结果表明,路基从完全饱和转为近饱和状态轨道中心处地面振动位移幅值变化显著;非饱和路基地面振动位移随时间衰减更快.距轨道中心8 m远处,同一速度下饱和路基路面振动持时大于非饱和路基;车速提高非饱和土振动持续时间变短,而饱和土地面振动持时变长.近轨道处200 km·h~(-1)下地面振动位移幅值大于其他速度且均以相当速率快速衰减;地面振动加速度级在某些车速下的衰减会出现反弹增大现象,其位置与车速密切相关.轨道中心处超静孔隙水压力主要分布在地表下4.5 m内,最大幅值出现在1.5～2.0 m深,且随路基饱和度降低显著减小.     

非稳定承压水降水引起土层沉降分布规律分析

承压含水层减压降水实质上是一个卸荷过程,其上覆土层沉降可用基于弹性半无限空间Mindlin位移解的推导公式进行计算.分析表明:无限承压含水层非稳定渗流降水时间对土层沉降影响显著;由承压水减压降水引起的土层分层沉降随距地表距离的增加而增大,最大值位于承压含水层顶板处;影响上覆土层沉降的7个参数中,泊松比和承压含水层渗透系数的变化对土层沉降影响很小;上覆土层厚度、承压含水层厚度越大地表沉降值越小;上覆土层弹性模量较小时对地表沉降影响较大,随着弹性模量的增加,其对地表沉降的影响逐渐减弱;地表沉降随单井出水量、承压水水头降深的增大而增加且近似成线性关系;单井出水量、承压含水层厚度、承压水水头降深、上覆土层弹性模量不仅影响地表沉降值的大小,还会影响地表沉降的空间分布.     

垂直集中表面荷载作用下非饱和土半空间中的Lamb问题

以多孔介质混合物理论为基础,同时引入土体双变量本构关系,得到了非饱和土中的一组动力控制方程.利用Hankel积分变换方法,对频域内的轴对称问题进行了求解.在此基础上研究了非饱和土半空间体在垂直集中力作用下的动力响应,给出了Lamb问题的积分形式解.当不计土中水、气的存在时,上述结果退化到单相弹性半空间中的经典Lamb解.数值计算结果表明:激振频率、渗透系数对地表位移影响显著,随激振频率的升高或渗透系数的降低,近场地表位移幅值减小,但当渗透系数低于一定值时,地表位移基本不再随其变化;饱和度对地表位移的直接影响是饱和度升高时,地表位移幅值略有减小.     

青藏铁路冻土路基活动层形成特性研究

在环境温度季节性变化的条件下进行室内模拟试验,探索了模拟冻土路基活动层形成的试验方法,研究了青藏高原多年冻土区路基活动层的形成活动规律。试验表明：活动层从初始形成到基本稳定过程中,近地表土层对外界温度场的变化响应灵敏,随外界温度的改变出现规律的波动;深层土层对外界温度的变化表现出滞后性,温度曲线波动幅度较小;活动层在趋于稳定的过程中土层的温度特征呈现出较为明显的区域相似性,在一定外温影响范围内土层温度场变化规律接近;在环境负温的初期表层土层迅速降温,活动层厚度开始逐渐减小,受外界气温及深层冻土冷源作用的共同影响,活动层冻结过程中会出现从上下边界同时冻结的现象,加快了活动层的冻结速度。     

饱和地基三维非轴对称动力响应

通过Laplace变换，建立了各向同性弹性饱和土在圆柱坐标系下，基于Laplace变换域内的Biot非轴对称波动方程；利用方位角的Fourier变换和径向Hankel变换，将波动方程转入为一组二阶常微分方程组；求解波动方程后，得到有限层厚的饱和地基的位移和应力通解;进而结合饱和地基的边界条件和排水条件，求解了任意竖向力作用下，饱和半空间地基的动力响应问题。     

黄土地区地上两层地铁车站抗震性能振动台试验

为研究黄土地区地下一层地上两层地铁车站结构的抗震性能,进行包括地上、地下结构及周围土层的振动台试验研究.在简要介绍模型设计和试验工况的基础上,重点根据试验中各传感器所记录的数据,对模型土箱的边界效应、模型地基与模型结构的动力反应、土与结构的相互作用等进行分析探讨.试验结果表明:地下一层地上两层地铁车站模型结构地上部分受输入地震动峰值加速度影响较大,地上部分的最终破坏模式是整体侧向倒塌;车站模型结构地下部分受地下结构周围土层影响较大,土层位移不大时地下结构无明显破坏;地上地下结构交接处的破坏最为严重.模型车站结构的存在对土体动力反应的影响较小,并随输入地震动峰值的增大而减弱.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

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     

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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