基于近场动力学的岩石不同应力路径损伤演化

加卸载效应普遍存在于各类岩土工程中,为研究岩体在不同应力路径下加卸载的力学响应和损伤演化规律,通过在传统键型近场动力学本构模型中引入键的损伤变量函数,以反映岩石材料应力应变曲线中先应变硬化再应变软化的非线性阶段,采用改进键型近场动力学模型数值模拟与室内细砂岩加卸载试验对照的方法研究了细砂岩在不同加卸载路径下的力学、损伤演化规律。结果表明：改进的键型近场动力学本构模型能够较好地模拟岩石材料先应变硬化再应变软化力学性质和在不同应力路径下的力学响应及损伤发展趋势;在常规三轴路径下,岩石的抗压强度与围压呈较严格的正相关变化;定义的损伤值可直观的对比出不同加卸载路径与常规三轴压缩下岩石的损伤发展情况,相对常规三轴压缩,卸荷路径加快了岩石材料的破坏,且升轴压破坏程度>恒轴压破坏程度>卸轴压破坏程度。     

MTS数字程控伺服岩石刚性试验机功能开发

介绍了以美国 MTS 815 Teststar型程控伺服单轴岩石刚性试验机为基本设备 ,配套开发的常规三轴、真三轴和直剪试验等功能组成的一个多功能数字程控伺服岩石力学试验系统的结构和性能。     

两种典型岩石在围压下的三轴应力实验研究

本文提供了两种标准岩石 和 在围压下的三轴应力试验,它对钻头设计及选型非常重要。通过岩石在围压下的三轴应力试验,获得了钻头使用及设计的一些有用数据。     

三轴SHPB岩石材料动力学特性试验研究的现状和发展趋势

岩石材料的三维动力特性试验研究是岩石冲击动力学中很重要的一个领域,也是目前研究的一个热点.本文论述了三轴SHPB岩石力学试验机的研制情况,对各类试验机的特点进行了比较.综合分析了三轴SHPB试验相关研究文献,总结了一些共有规律:①在围压一定的情况下,岩石的动态抗压强度会随着应变率的增加而增加,呈现出线性函数或者指数函数增加形式,并且脆性减弱,塑性显著增加;②在应变率一定的情况下,岩石抗压强度会随着围压的增大而增大,线性关系比较显著:③岩石动静组合加载时,在轴压一定时,岩石的动静组合抗压强度会随着围压的增大而增大,呈现出近似线性增加趋势;在围压固定时,抗压强度随着轴向静压的增大呈现出先增大后减小的趋势.由于SHPB试验装置和岩石材料本身的特点.目前在一些基本问题上.如加载应力波形、试样尺寸要求等方面.还没有统一的试验规范要求,很多试验结果只能进行定性比较.无法在统一尺度上进行定量分析.最后,针对该领域的发展趋势进行了论述,指出尽快建立一套国际性的建议试验方法是将来的一个关键问题.     

用点荷载强度指数确定岩石三轴抗压强度及岩石C、φ值的探讨

本论文在完成试验的基础上,引用有关资料,在探讨用I_(s)确定三轴抗压强度方面取得一定的效果。主要根据试验,通过计算,用岩石点荷载强度,运用别尼亚夫斯基公式,近似地确定岩石的三轴抗压强度表达式,强度曲线及岩石的C、φ值。并经对比实验和A、M值确定规则,获得了八种岩石的A、M值及其近似的强度曲线。     

考虑水-力耦合和不同应力路径的砂岩卸荷力学特性试验

为研究不同渗透压力条件下的岩石卸荷力学特性,选取砂岩为研究对象,开展了不同渗透压力和不同应力路径下的三轴卸荷试验,并与常规三轴试验进行对比,比较了不同应力路径下的岩石强度特性,分析了渗透压力对岩石变形和强度参数的影响。试验结果表明：渗透压力的增大会弱化岩石强度,岩石的峰值强度随渗透压力的增大而降低,而轴向变形随渗透压力增大而增加,渗透压力越大,岩石的压密段特征越明显;针对两种不同的卸荷应力路径,恒轴压卸围压路径条件下,岩石的黏聚力不断降低,内摩擦角不断增加,而加轴压卸围压路径条件下,岩石的黏聚力不断增加,内摩擦角逐渐降低。     

岩石连续损伤统计本构模型

基于岩石微元强度概率分布理论 ,以Drucker Prager破坏准则为统计分布变量 ,建立了理论的岩石损伤变量演化方程和三轴条件下岩石损伤弹性统计本构模型。利用任意条件下的三轴试验数据 ,用曲线拟合法和极值法求解了所建模型的参数 ,并用试验结果对所建模型进行了验证。模型计算结果与试验结果吻合较好 ,这说明用Drucker Prager准则为统计分布变量建立的损伤模型能够较好地反映岩石内部缺陷分布和变形特征 ,表征岩石材料在弹性阶段的本构关系。     

基于Mohr-Coulomb准则的岩石损伤统计分析方法研究

从探讨基于Mohr-Coulomb准则的新的岩石微元强度表示方法及其服从Weibull随机分布的特点出发,基于岩石三轴应力应变试验曲线,建立了反映岩石破裂全过程的损伤软化统计本构模型．在此基础上,重点研究了Weibull分布参数对岩石损伤软化统计本构模型的影响,并结合岩石三轴应力应变试验曲线的特征,对岩石损伤软化统计本构模型进行了合理修正．与试验结果及前人研究结果比较,该模型形式简单,能更好地反映工程实际,具有广阔的应用前景。     

三峡工程花岗岩卸荷全过程特性的试验研究

在常规三轴室中进行了花岗岩试件在恒定轴压下的围压却荷试验份析了岩石在卸荷条件下的变形和强度特性,回归得到由卸荷导致岩石破坏的强度经验准则．     

基于MSV方法削弱端部摩擦效应的三轴力学试验研究

为了研究三轴力学试验中MSV方法对于削弱端部摩擦效应的作用,选取粉砂岩作为研究对象,利用岩石全自动多场耦合三轴试验系统,开展不同围压等级下基于MSV方法的三轴力学试验研究,同时对照开展不同围压等级下不同高径比(2.0,2.5)的三轴力学试验研究.对比分析了三轴力学试验中不同围压等级下MSV方法对于岩石强度特性、变形特性以及破坏形式的影响.研究结果表明:MSV方法通过减小压头与试样端面的摩擦系数一定程度上削弱了端部摩擦效应对强度的影响;与对照组相比,采用MSV方法进行试验得到的强度较低,弹性模量偏小、泊松比偏大,且两者随围压的变化幅度均小于对照组的测量值,说明试样变形对端部效应的敏感度降低;MSV方法在各围压等级下均可得到较理想的剪切破坏裂纹.研究结果可为室内岩石力学试验端部摩擦效应研究以及三轴力学试验的改进提供参考意见.     

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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