气煤热力耦合变形与孔隙演化特征的实验研究

采用自主研制的"600℃20 MN伺服控制高温高压岩体三轴试验机",进行直径×高度为200 mm×400 mm的山东兴隆庄气煤试样高温三轴应力下的耦合热变形实验,对实验后的煤样采样,与非实验煤样进行对照压汞实验及孔隙结构分析。研究结果表明:三轴恒定应力下,气煤随温度升高的热变形可分为3个阶段:缓慢变形阶段、快速变形阶段和破坏阶段;试样由缓慢变形阶段进入快速变形阶段、渗透率激变以及脆韧转化三者具有相同的阀值,都是因气煤热解产生孔隙所致;三轴应力下气煤随温度升高的热变形特征和渗透性变化规律均由大孔的发育程度决定,且试样压缩的空间取决于大孔的体积。     

煤岩蠕变声发射特征试验研究

利用MTS815岩石伺服试验系统和AE21C声发射监测系统对煤岩进行了分级加载声发射试验.试验结果分析表明,煤岩分级加载过程存在蠕变应力阈值,在达到该阈值之前,各个应力水平上的煤岩变形很不明显,当加载水平大于该阈值时才发生明显蠕变变形.在瞬态蠕变阶段,煤岩内微孔隙、裂隙逐渐扩展,声发射活动逐渐增强;在稳定蠕变阶段煤岩蠕变变形速率趋于平稳,新生裂隙较少,声发射事件少且能量低;在加速蠕变阶段煤体内产生大量裂隙并逐渐发育至宏观破裂失稳,储存的能量在较短的时间内快速释放,声发射事件数及能量均达到最大值.煤岩的声发射特征较好地反映了其蠕变过程中的损伤演化过程.     

深部花岗岩50℃卸荷蠕变试验研究

为研究深部花岗岩在温度作用下的卸荷蠕变特性,采用岩石全自动三轴流变仪开展了花岗岩在温度50℃、围压10、20、30 MPa条件下的卸荷蠕变试验,分析了花岗岩高温卸荷蠕变特征、宏观破坏模式和微细观损伤破坏机理.试验结果表明:在温度效应条件下,花岗岩高压卸荷蠕变会产生较大变形;50℃卸荷蠕变条件下,花岗岩的蠕变性能随着围压的卸载而呈指数变化,初始卸荷围压越高,花岗岩越早出现蠕变变形;花岗岩高温卸荷蠕变破坏模式主要为共轭剪切破坏,蠕变作用促使岩石内部损伤裂隙扩展并形成裂隙面而失效破坏;岩石高温卸荷蠕变破坏强度约为常温三轴强度的1/3,其黏聚力和内摩擦角也比常规指标减少30%以上.     

“鲁灰”花岗岩热破裂的细观结构及规律

岩石的组分和细观结构决定其宏观力学性质.通过显微光度计对"鲁灰"花岗岩的矿物组分及微结构,及其在不同温度下的热破裂行为进行观测.试验中发现:"鲁灰"花岗岩为多种组分所构成,非均质性明显;温度作用下,花岗岩内部晶体颗粒之间胶结物的变化,晶粒内部产生的位错及微破裂,导致花岗岩产生热损伤破裂行为.通过对花岗岩的微裂纹发展变化进行定量分析得知:温度作用下微裂纹、内部微结构的发展变化具有规律性.花岗岩的微裂纹数量在80℃出现微幅变化;当温度升高到240～260℃时,"鲁灰"花岗岩的裂纹数量出现剧烈增长;确定了花岗岩破裂行为的阈值.     

20g钢高温裂纹扩展控制参量

在20g钢高温裂纹扩展实验基础上,将裂纹扩展速率da/dt分别与断裂参量静截面应力σnet、应力强度因子K和C积分相关联,以寻求非稳态蠕变扩展阶段,高温裂纹扩展速率的恰当控制参量·研究结果表明:断裂参量静截面应力、应力强度因子与裂纹扩展速率之间的关系受到加载速率和温度影响·在400℃和500℃下,C积分与裂纹扩展速率均存在着惟一的关系·用C积分控制20g钢高温裂纹扩展速率da/dt较合适,并建立了20g钢高温裂纹扩展速率da/dt的控制方程     

热损伤花岗岩三轴压缩蠕变破坏声发射及损伤演化特征

为探究深部高温高压环境对工程围岩蠕变性质的影响,开展了不同程度热损伤花岗岩的三轴分级蠕变加载试验,分析其声发射活动及损伤演化特征。研究结果表明：在分级蠕变加载中,当轴向应力达到1.50～1.65倍损伤应力σ_cd后,花岗岩损伤演化加快,达到(1.65～1.80)σ_cd后,发生加速蠕变破坏;在同一级加载中,随热处理温度升高,声发射活动在减速蠕变和稳态蠕变阶段减弱,在加速蠕变阶段增强;围压效应可以减弱热损伤对花岗岩蠕变特性的影响,围压与热损伤的耦合效应可以抑制蠕变过程的裂纹扩展,但当轴向应力增大、岩石失稳后热损伤对蠕变破坏加剧起控制作用;在分级加载过程中,随热处理温度升高,损伤变量的增长趋势先减缓后加快,600℃热处理试样损伤发展最快,常温试样次之,150℃和300℃热处理试样最慢;蠕变过程中剪切裂纹占比在35%～60%,随分级加载应力增大,微裂纹类型向剪切型转化;热损伤花岗岩矿物晶粒内和晶界裂纹有不同程度的发育,导致剪切裂纹占比随热处理温度升高而先减小后增大。     

Ti-55511合金高温蠕变行为TEM分析

文章结合Ti-55511钛合金的高温工作环境进行了4组蠕变实验：400℃200MPa、400℃300MPa、500℃200MPa以及500℃300MPa。蠕变后,使用透射电镜实验观察了蠕变后样品的微观组织。结果表明：高温高应力状态下,位错攀移在蠕变过程中占主导地位;在高温低应力或低温高应力状态下,合金蠕变过程主导机制为位错滑移;当温度较低,应力相对较低时,合金蠕变过程中主导机制为晶界扩散机制。     

真三轴岩爆试验下三类岩石力学特性及声发射特性研究

为研究同一矿山环境下不同岩性岩石的岩爆发生发展规律，利用真三轴试验系统和声发射监测系统对大理岩、花岗岩、矽卡岩进行应变型岩爆模拟，并对三类岩石的力学特性和声发射特征参数进行分析.研究结果表明：三类岩石的三轴抗压强度从高到低依次为矽卡岩、花岗岩、大理岩.三类岩石在岩爆模拟过程中均可划分为孔隙压密阶段、弹性变形阶段、裂隙稳定扩展阶段、裂隙不稳定扩展阶段、岩爆后阶段.三类岩石在孔隙压密阶段的声发射特征参数均表现为累计振铃计数和累计绝对能量小幅增长、b值轻微波动，说明此阶段三类岩石内部产生的裂纹均较少.大理岩与矽卡岩均在裂隙不稳定扩展阶段开始出现累计振铃计数和累计绝对能量的大幅增长以及b值的剧烈波动，花岗岩则从弹性变形阶段就开始出现这些变化，说明花岗岩内部破裂的发生时间更早.在破坏形式上，大理岩与矽卡岩的张拉破坏占比更大，花岗岩则发生张剪混合破坏.     

周期荷载作用下冻融裂隙砂岩变形破坏机理

为研究裂隙岩体在冻融与周期荷载作用下的变形破坏机理,采用宏观周期荷载试验与细观核磁共振试验以及颗粒流数值模拟相结合的方法,对不同冻融循环次数作用下裂隙砂岩的宏细观破坏机理进行研究。结果表明：冻融次数的增加使裂隙砂岩强度降低,破坏时扩容现象加剧,细观尺度上表现出孔隙尺寸及数量增加;冻融及周期荷载耦合作用使裂隙砂岩破坏裂纹发展多且复杂,破坏程度更严重,细观表现为T2谱峰总面积变化率增幅更加显著、大尺度孔隙占比增加;周期荷载作用下裂隙砂岩的变形曲线趋势可作为判断疲劳强度门槛值范围的依据,获取变形预警值;颗粒流模拟结果说明,周期荷载作用下裂隙砂岩的新的裂纹在预制裂隙尖端处集中萌生并以翼裂纹为主要扩展模式,围压作用下裂隙砂岩的破坏模式更趋向于剪切张拉复合型破坏。研究结果可为寒区裂隙岩体边坡稳定性评价及灾害防治提供参考。     

金坛储气库岩盐蠕变特性及其实用本构研究

通过对金坛盐矿储气库岩盐大量的实验发现:在不同应力水平作用下,岩盐的瞬态蠕变变形介于0.1%到2%之间,一般高应力水平作用下的变形量较低应力水平作用下的变形大;试件的稳态蠕变率从0.0023%/h到0.15%/h变化不等,随应力水平的提高,岩盐蠕变率变化十分明显。表明:应力水平越高,瞬态蠕变变形和稳态蠕变率均越大;反之亦然。在分析应力水平与蠕变变形关系实验及理论分析的基础上,结合金坛储气库实际,建立了基于应力水平的岩盐瞬态及稳态蠕变综合本构方程。该本构方程理论计算与实验结果吻合较好,可为金坛储气库运营的稳定性分析提供一定的参考依据。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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