对砌体剪-压破坏准则的研究

对现有国内外剪压砌体破坏准则进行了分析比较,并指出了其中的不足.基于力学原理,采用数理统计分析法建立了剪-压砌体破坏准则.相对而言,该破坏准则不仅能反映剪-压砌体可能出现的各种破坏形式,而且不同破坏形式之间有明确的界限,力学概念明确,适用于各类砌体.由该准则推得的砌体抗剪强度计算值与试验结果、现行规范取值吻合较好,形式简单,便于计算,可供砌体结构理论分析和工程设计时参考.     

承重型横孔连锁混凝土砌块砌体的抗剪性能

为研究承重型横孔连锁混凝土砌块砌体的抗剪性能,采用3种块型的砌块制作了砌体抗剪试件.每种块型的砌块试件均以3种砂浆强度为变量.首先对试件进行了静力剪切加载试验,观察试验现象,记录剪切破坏荷载.然后分析了影响砌体抗剪强度的主要因素,并和其他混凝土砌块砌体抗剪强度的试验结果以及规范计算值进行了对比.最后提出了考虑有效黏结面积计算混凝土砌块砌体抗剪强度的方法.研究结果表明:承重型横孔连锁混凝土砌块砌体的剪切破坏均为砂浆与混凝土砌块接触面的黏结剪切破坏.计算砌体抗剪强度时,应采用砂浆与砌块接触面的有效黏结面积;在此基础上,提出了承重型横孔连锁混凝土砌块砌体抗剪强度的计算方法,该方法不但可以准确计算该砌块砌体的抗剪强度,而且可以计算其他类型混凝土砌块砌体基于黏结剪切破坏的抗剪强度.     

N式砌块砌体受剪性能试验研究

对30个N式砌块砌体抗剪试件(其中未灌孔试件6个,灌孔试件24个)进行了受剪力学性能试验研究,了解了N式砌块砌体的破坏形态及破坏机理.试验结果表明,灌孔N式砌块砌体的受剪开裂荷载与极限荷载的比值随灌孔率的不同分别为:半灌孔试件77%~82%、全灌孔试件54%~59%.随着灌孔混凝土面积的增大,N式砌块砌体表现出越来越好的延性.未灌孔N式砌块砌体的抗剪强度平均值比砌体规范抗剪平均强度公式计算值高出11%,半灌孔N式砌块砌体的抗剪强度平均值比砌体规范平均强度计算值高出5%,全灌孔N式砌块砌体的抗剪强度平均值比砌体规范平均强度计算值高出74%~106%.     

混凝土普通砖砌体受剪性能试验研究

通过对混凝土普通砖砌体抗剪强度的试验研究和对试验结果的分析,得出混凝土普通砖这种新型墙体材料的抗剪强度规律及其抗剪破坏特征.结果表明,砂浆强度相同条件下,混凝土普通砖砌体的抗剪强度高于普通烧结砖砌体强度的规范计算值.提出混凝土普通砖砌体抗剪强度平均值的计算公式.     

开槽砌块灌孔砌体的抗剪性能试验研究

通过对开槽砌块灌孔砌体的抗剪试件的静力试验研究,了解了开槽砌块灌孔砌体的试件开裂荷载、极限承载力、破坏过程和破坏特征.试验结果表明,开槽砌块灌孔砌体和普通灌孔砌块砌体相比,其抗剪强度得到一定程度的提高.分析了影响灌孔砌块砌体抗剪强度的多种因素,并根据Hoffman准则以及现行的规范公式,建立了开槽砌块灌孔砌体的抗剪强度公式,公式的计算结果与实验结果吻合较好.建立了开槽与不开槽砌块灌孔砌体抗剪强度的统一表达式,结果表明,将其运用在不开槽砌块的抗剪强度的计算中是可行的.     

灰砂蒸压加气混凝土砌体剪压复合受力性能试验

为了解砌体结构在实际工程中所处的剪压复合的复杂受力状态,作用在砌体上的正应力对砌体的抗剪性能、砌体的剪切破坏形态及其对砌体抗剪强度的影响,对54个小型灰砂蒸压加气混凝土砌体进行静力抗剪试验,通过施加不同的正应力得到相应的抗剪强度;分析其破坏机理,归纳得出剪摩、剪压、斜压等破坏形态,并与砖砌体的破坏形态进行比较;根据试验结果回归分析得到灰砂蒸压加气混凝土砌体的静力剪压相关性曲线,与砖砌体的剪压相关性曲线进行对比分析,得到两者的异同;在静力剪压相关性曲线的基础上,依据变摩擦系数的剪摩理论,提出灰砂蒸压加气混凝土砌体静力抗剪强度的建议公式,并对摩擦系数进行了简化.     

自嵌固生土砖砌体剪压复合受力试验研究

为了研究自嵌固生土砖砌体嵌固部位在剪压复合作用下的承载能力,在考虑其承受不同上部竖向荷载的情况下对18个自嵌固生土砖砌体试件进行了剪压复合受力试验,探究其受力性能、破坏机理及剪压相关性.试验表明砖体间咬合嵌固可起到销栓作用,表现出较好的抗剪能力.分析总结了砌体剪切、剪压和斜压三类破坏形态产生的主因,提出了自嵌固生土砖砌体剪压复合受力下砌体的抗剪强度计算公式,并与传统主拉应力破坏理论中砌体抗剪强度计算方法进行了对比,发现主拉应力破坏理论计算出的砌体抗剪承载力安全可靠,但较为保守.研究可为自嵌固生土砖砌体力学性能的进一步研究及设计应用提供试验成果及理论依据.     

“工”型有盖空心小砖砌体伪静力试验研究

对7片"工"型有盖空心小砖砌体(黄土素泥1mm厚砌体5片、水泥净浆1mm厚砌体和水泥砂浆5mm厚砌体各1片)进行伪静力试验研究.试验结果表明:砌体的抗剪能力与轴压比有关,当轴压比小于0.7时,试件的抗剪能力随着轴压比的增大而提高,结构延性也随之改善;当轴压比为0.7时,砌体的结构性能达到极值;当轴压比大于0.7时,砌体的结构性能由极值开始下降.砌体齿缝的咬合作用使砌块充分发挥了其抗剪强度,提高了砌体的抗剪能力,齿缝的存在起到了一定的耗能作用,有利于改善砌体的抗震性能.黏结材料的强度和厚度对砌体抗剪能力贡献不显著,即"工"型有盖空心砌块适合使用低强度薄灰缝的黏结材料,由此降低工程成本、增大应用范围.     

粉煤灰烧结保温砖砌体基本力学性能试验研究

为研究粉煤灰烧结保温砖砌体抗压、通缝抗剪、剪-压复合受力3方面性能,采用试验和理论计算的方法,对砌块砌体进行试验研究,得出相应的抗压强度标准值和设计值的建议取值;在对应力—应变实测曲线回归分析的基础上,得出粉煤灰烧结保温砖砌体应力—应变曲线的函数表达式,并给出弹性模量和泊松比的实测值;得出粉煤灰烧结保温砖砌体通缝抗剪强度的平均值和计算式;得出粉煤灰烧结保温砖砌体剪压复合受力抗剪强度平均值的建议计算式;掌握了该型砌体的主要破坏特征,并为后续研究及该类型砌体的推广应用提供基本的力学性能参数。     

约束页岩砖砌体墙抗震性能试验研究

通过9片约束页岩砖砌体墙的低周反复水平荷载试验，研究了约束页岩砖砌体墙的破坏特征、抗震性能和抗震受剪承载力计算公式．试验表明约束页岩砖砌体墙具有良好的变形性能和较高的抗震受剪承载力，其延性系数接近约束粘土砖砌体墙延性系数，其抗震受剪承载力计算式可采用与约束粘土砖砌体墙相同的公式．在抗震性能上页岩砖完全可以取代粘土砖作为约束砌体墙的砌筑材料．     

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