可液化土中地铁结构的地震响应

在饱和土耦合作用与土和结构相互作用理论基础上,以地铁车站为例,用有限元法研究地下结构在地震液化作用下的响应。所采用的软件为动力两相体非线性有限元软件Dyna-Swandyne-II,该软件可以应用先进的Pastor-Zienkiewicz III广义塑性模型模拟可液化土的动力特性,应用u-p形式的Biot方程,在有限元分析中充分考虑孔隙水与土之间的耦合,同时考虑地下结构与饱和土在动力作用下的非线性相互作用。分析了地铁车站的动力响应,包括地铁内力、加速度以及地铁位移。研究结果表明,地铁结构在地震液化作用下会产生较大的上浮,从而对结构造成比较严重的破坏;地铁结构在地震作用下的最大内力位于结构的交接处。因此,结构交接处的配筋应该格外小心。     

局部加载条件下二维土质边坡稳定性的数值分析

借助Hill的材料应变局部化原理和土的弹塑性本构模型,应用声学张量示踪边坡失稳滑移线发生和发展,提出了局部加载条件下的确定边坡失稳滑移线的方法。在弹塑性有限元分析过程中,应用边坡材料的塑性一致性条件或滑移线两侧的应力连续条件,即应变局部化条件,检测每一个高斯点的声学张量行列式的值,当其等于或接近0时,标出滑移萌生的位置、方向,模拟边坡滑移线萌生和发展过程。     

土与结构间接触面的非线性弹性-理想塑性模型及其应用

将非线性弹性理论与弹塑性理论相结合,对于土与结构间接触面提出了一种非线性弹性-理想塑性模型,用于模拟土与结构相互作用体系的变形与破坏机理。推导建立了这种接触面单元的应力-应变关系和弹塑性系数矩阵,并且讨论了这种模型在基坑开挖与支护分析应用中所面临的数值计算问题。最后针对某一基坑工程实例,应用这种接触面模型进行了数值计算与分析,结果表明,该模型能够较合理地模拟接触面上的变形机理与受力状态。     

土-地铁隧道动力相互作用模型试验分析

本文对土的动力特性本构模型以及土-结构的接触面模型进行了较详细的探讨,最后分别选用非线性等价粘弹性模型和Ramberg-Osgood模型。分析表明,在进行模型试验设计时,不仅材料要满足相似性原理,而且在设计边界条件和地震波输入时也应以上述模型为参照。通过对一圆形隧道的地震反应分析,表明拱顶处的最大动应力是圆形隧道出现裂痕的主要原因,进而分析了孔隙率对结构横向变形的影响,分析结果与实际工程情况较为吻合。本文的研究成果可为地铁隧道的抗震设计提供一定的参考意见。     

近远场地震动作用下地铁车站结构地基液化效应的振动台试验

开展了近场和远场地震动作用下3跨3层地铁车站结构地基液化效应的振动台模型试验,测试了地铁车站结构的加速度、应变、水平位移反应和地基土孔隙水压力、加速度、震陷及其作用于模型结构侧墙的动土压力反应。分析和总结了地铁车站结构地基液化效应特征,结果表明：模型结构对其周围地基土孔隙水压力场的分布有明显影响,结构两侧和底部地基土中的孔压峰值小于相同深度离结构较远地基土中的孔压峰值;地基土中孔压的消散速度自下而上呈逐渐减慢的趋势;地震动作用过程中,模型结构产生向上的相对运动,强地震动作用时模型结构上浮现象明显;模型结构侧墙受到的动土压力随深度增大而减小,输入地震动特性对动土压力的大小有显著影响。     

基于Weibull分布的黄土状土的单轴损伤模型

通过扫描电镜和偏光显微镜对不同方向切面试样的观察,分析了损伤前后黄土状土微观结构的变化。分析结果表明:受力前黄土状土呈粒状架空接触结构,石英、长石、伊利石及高岭石等矿物在试样中分布杂乱无定向性。黄土状土的单轴压缩过程分为3个阶段:第一阶段为压密阶段,此阶段土体中微裂隙闭合,大孔隙变成为微孔隙; 第二阶段为峰值应力前开始损伤阶段,此阶段土体微结构转为镶嵌微孔微胶结结构,颗粒之间产生滑移,原有和新生的小裂隙变宽、变长; 第三阶段峰值应力后损伤快速发展,孔洞、裂隙连通,矿物发生明显定向。在此基础上,利用黄土状土微元强度服从Weibull随机分布的特点,运用统计损伤理论,并考虑到黄土状土的含水率、损伤门槛的影响,建立了考虑损伤门槛的损伤本构方程。以黄土状土的单轴压缩试验结果作为实例,进行了验证。理论计算结果与试验结果对比表明,该模型能够较好地描述黄土状土的变形破坏全应力-应变试验曲线。     

桩-土-承台结构在波浪力作用下的力学效应分析

在港口桥梁工程和海洋工程中,一般将桩从桩-土-承台结构中分离出来,单独计算波浪力对桩的作用。在提出波浪力作用下桩-土-承台结构相互作用模型的基础上,结合工程算例,进行了桩-土-承台结构在波浪力作用下桩的荷载和弯矩计算分析,结果表明：在不考虑波浪力的情况下,计算结果跟规范方法较为接近,验证了桩-土相互作用模型的适用性。在此基础上迭加波浪力,将波浪力和桩-土-承台作为一个完整的系统研究,随着承台所受外力、波浪力、桩侧地基土的变化,分析了桩-土-承台结构在波浪力作用下的受力效应。     

粗粒料接触面模型及其在土石坝工程中的应用

在土石坝工程中越来越重视岸坡与坝料之间的接触特性,将土体本构模型中使用较多的双曲线型硬化规律运用至接触面模型,提出了一个简洁的接触面本构模型,推导了接触面模型刚度矩阵表达式。通过对4组试验的预测结果与试验结果的对比,表明该模型可以较好地预测粗粒料的界面剪切试验。将提出的接触面模型嵌入有限元程序,应用于如美心墙坝河谷与坝料的接触分析。三维有限元计算结果表明：坝体两侧岸坡的剪切位移变化规律都是中间部分剪切滑移量较大,岸坡边缘部分相对较小,陡坡一侧最大滑移量大于较缓一侧。这些均符合粗粒料滑移的基本规律,可为岸坡?坝料接触特性研究以及土石坝工程计算提供参考。     

水泥土桩加固边坡变形破坏特性及模型试验分析

水泥土桩是软土边坡常用的一种较经济的加固结构,但目前对水泥土桩加固边坡的变形破坏特性和抗滑机制认识不清,相应的稳定性评价理论研究较少。建立了一边坡模型,运用有限元分析了离散水泥土桩加固边坡的变形破坏特性,结果发现边坡失稳时,桩-土之间由于变形不协调而产生塑性滑移,强度和刚度都较大的水泥土桩呈S型挠曲变形而发生弯折破坏,未能有效发挥设计要求的抗滑能力,加固边坡最后形成贯通的剪切滑动带而非滑动面。提出了水泥土剪力墙的概念,通过有限元模拟发现,采用水泥土剪力墙加固边坡,因墙-土界面摩擦力的作用,下滑力在剪力墙和边坡滑体之间得到调整,最终促使加固边坡产生整体剪切破坏,有效发挥了剪力墙的抗滑能力。通过桩土复合结构的水平推剪模型试验,验证了数值模拟结果的合理性。     

土-地下结构体系地震反应的简化分析方法

基于Penzien提出的土-结构动力相互作用分析的集中质量模型,考虑等价土体的层间剪切刚度与阻尼效应,提出了土-地下结构动力相互作用体系地震反应分析的简化分析方法,选取具有不同地震动特性的Taft波、汶川地震什邡八角波和松潘波作为基岩水平向输入地震动,采用该简化方法和二维有限元法对土-地铁地下车站结构体系的地震加速度反应特性进行了对比分析,结果表明：简化方法计算的地铁地下车站结构峰值加速度反应大于二维有限元法计算的地铁地下车站结构峰值加速度反应,两者的差异与输入地震动特性有关,但其随地铁地下车站结构高度变化的总体趋势较为一致;随着输入地震动强度的增大,其差异程度也有所加大。该简化方法可合理反映土-地下结构体系的动力相互作用效应,可作为地下结构抗震设计分析的一种辅助方法。     

Unity of the national and the international in the socio-cultural development of the peoples of the USSR

International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen.     

Global repeating events in the history of the Earth and the motion of the Sun in the Galaxy

Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated.     

Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth

It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T ₃ = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″.     

从榴辉岩与围岩的关系论苏鲁榴辉岩的形成与折返

位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压，而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩，榴辉岩及其他直接围岩皆呈包体存在于其中，并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体，表明新元古代花岗岩的组成物质也经受过超高压变质作用，且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次（或阶段）却少于榴辉岩。椐上述可得如下推断：超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部（俯冲板块前部）形成的；榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的，其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升，遭受剥蚀。     

某高速公路下伏煤矿采空区稳定性分析

在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。      

摩擦桩基桩土间极限摩阻力取值问题探讨

通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。     

The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads

In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.     

Paleomagnetic implications on the evolution of the tethys belt from the atlantic ocean to the pamirs since the triassic

We first re-examined the apparent polar wander curves for stable Eurasia and Africa since the Triassic. These curves were then combined together with curves of North and South America according to the kinematics of the Atlantic ocean and a synthetic polar wander curve was given. Then, most of the paleomagnetic results from the Tethys mobile belt, from the Atlantic to the Pamirs, were analysed.Several groups of plates, microplates and blocks can be seen. First, relatively stable regions like Maghreb and Sicily, which have not moved much. Then we have a group formed by Iberia, Sardinia, Italy and, to a lesser extent, Corsica and the Western and Central Alps. For these blocks, movements are anticlockwise rotations chiefly driven by the anticlockwise rotation of Africa, but they are sometimes stronger.To the east, a major change takes place. The north of the Aegean Sea and the Ionian zone are clockwise rotated and these rotations are recent: Oligocene-Miocene for the first part, Pliocene to the present for the second part.A major problem arises in Turkey, Caucasus and Iran. Paleomagnetic results indicate a position far to the south of Eurasia, and, at the same time, geological evidence is in favour of a position close to Eurasia. We discuss these discrepancies.