库水位变动条件下柱状危岩体变形破坏机理

三峡水库周期性水位变动造成了部分消落带岩体劣化,其具体表现为强度下降和宏观裂隙增多,这使得一些柱状危岩体被发现或需要重新认识,包括箭穿洞、曲子滩和棺木岭等危岩体。这些柱状危岩体三维边界清晰,由"硬-相对软"的岩性组成,主要受控于相对软的硬岩基座岩体。采用伪时间增量的方式模拟岩石强度的时间相关劣化效应,数值分析了多水位变动周期下棺木岭危岩体裂缝和破坏区的扩展情况。危岩体初始破坏区主要集中在基座趾部岩体。随着水位变动周期增多,裂缝和破坏区由危岩体踵部和趾部相对扩展,破坏区主要集中在危岩体踵部。10次水位周期计算所得破坏区比相同时步、没有劣化效应时增加了近4倍,且以拉张破坏为主。周期性水位变动造成的岩体劣化强烈加快了柱状危岩体演化进程,同时影响了其破坏机理。从数值分析来看,棺木岭危岩体的变形破坏模式从原来的倾倒为主将转为以压溃崩塌为主。水位变动条件下岩石强度的时间相关劣化效应及其对柱状危岩体的影响研究将为三峡水库危岩体防治提供重要技术支撑。     

三峡库区箭穿洞危岩体变形破坏模式与防治效果分析

本文以三峡库区箭穿洞危岩体为例,对涉水厚层危岩体的变形破坏模式和防护措施进行了研究。根据现场调查和长期监测数据可知,干湿循环作用下基座岩体的劣化是加速箭穿洞危岩体变形破坏的主导因素,并判定其破坏模式为基座滑移式崩塌。在此基础上,将危岩体的防护治理定为两部分,分别是基座软弱岩体的补强加固,以及中上部危岩体的锚索加固。通过数值模拟对防护前后危岩体的位移场以及应力场进行了分析,结果表明危岩体上部的锚索加固能够有效控制岩体的变形,基座补强能够有效控制危岩体的最大剪应力,综合防护可以显著提高箭穿洞危岩体的稳定性。该防护措施的理念及方法,可以为库区涉水危岩体的治理提供重要的参考价值。     

三峡库区巫峡箭穿洞危岩体稳定性分析及防治工程设计

箭穿洞危岩体壁立于三峡库区巫峡左岸,区内属神女峰风景旅游区,每天有大量的船舶从危岩体前方航道通过,潜在涌浪威胁到长江航道安全。箭穿洞危岩体的后缘高程为305 m,基座高程为155 m,平均高差为135 m,平均危岩横宽约50 m,平均厚度约55 m,崩塌体体积约3.575×105m3。箭穿洞危岩体基座为泥质条带灰岩,在库水波动下基座岩体劣化强烈;干湿循环试验表明基座岩体强度下降约20%~30%,危岩体可能发生基座压裂滑移或倾倒破坏。箭穿洞危岩体在145 m、175 m静水位工况条件下为稳定,暴雨+162 m洪水位工况下为基本稳定状态,在考虑基座岩体劣化的工况下处于极限平衡状态。箭穿洞危岩体防治工程等级为Ⅰ级,设计方案采用基座软弱岩体补强加固+锚索锚固。基座岩体在持续劣化,建议尽快启动箭穿洞危岩的治理工作。     

三峡库区近水平厚层斜坡滑动稳定性研究——以重庆巫山箭穿洞危岩为例

以重庆巫山箭穿洞近水平巨厚层危岩体为例,通过地质环境条件、基座位移及应力监测数据等分析,总结归纳了危岩体目前的变形和受力状态,发现危岩体的强度仍在持续降低。同时,运用FLAC2D模拟手段,设置了初始天然、初始饱和、临滑、失稳4种模拟工况,研究了危岩基座岩体及泥质条带灰岩层面对危岩体阻滑规律。研究结果表明,基座泥质条带灰岩层强度的持续降低将会使得危岩体处于临滑乃至失稳状态。该稳定性分析也为进一步的防治设计提供了依据。      

三峡库区秭归县棺木岭危岩体发育特征及成因机制探讨

棺木岭危岩体为三峡库区新发现的崩塌隐患点,呈不规则塔柱状,平均高约50 m,宽约50 m,厚约20 m,体积约5×104m3。本文基于野外地质调查,在分析棺木岭危岩体发育特征及形成原因的基础上,对其形成机制及可能破坏模式进行初步研究。调查和分析表明:陡峻地形、上硬下软的岩体介质结构、构造裂隙切割是危岩形成的主要原因,水库蓄水和降雨是危岩体破坏的外在激发因素,尤其是库水位周期性涨落加剧了基座岩体的破坏,加速了危岩体形成演化;其成因机制为下伏软弱基座在上覆硬岩巨大自重荷载作用下压裂破坏,引起山体变形开裂形成,危岩体可能破坏模式为倾倒破坏或座滑破坏;其形成演化过程可以分为以下4个阶段:卸荷裂隙形成阶段、软弱基座差异沉降与裂隙扩展阶段、水库蓄水加剧裂隙贯通与基座岩体碎裂化阶段、崩塌与堆积阶段。     

基于实测的望霞W1危岩体失稳动态过程分析

在地质调查和现场监测的基础上,研究了望霞W1危岩体变形-演化的动力学过程。危岩体位于重庆市巫山县两坪乡,受裂隙切割成柱状。岩性为中厚层硅质、泥质灰岩夹燧石层,危岩体下部基座为粉砂岩、粘土岩及煤线,形成上硬下软的地层结构。研究表明:危岩体局部变形失稳过程与整体失稳过程的位移变形曲线表现出相似性,可划分为前期累积变形、匀速变形、加速变形和临界加速变形等四个阶段。望霞危岩的特殊地质结构、地质环境为危岩的孕育和破坏提供了地质基础。人为活动和降雨对危岩的变形破坏具有显著的影响。     

基于实测的望霞W1危岩体失稳动态过程分析

在地质调查和现场监测的基础上,研究了望霞W1危岩体变形-演化的动力学过程。危岩体位于重庆市巫山县两坪乡,受裂隙切割成柱状。岩性为中厚层硅质、泥质灰岩夹燧石层,危岩体下部基座为粉砂岩、粘土岩及煤线,形成上硬下软的地层结构。研究表明:危岩体局部变形失稳过程与整体失稳过程的位移变形曲线表现出相似性,可划分为前期累积变形、匀速变形、加速变形和临界加速变形等四个阶段。望霞危岩的特殊地质结构、地质环境为危岩的孕育和破坏提供了地质基础。人为活动和降雨对危岩的变形破坏具有显著的影响。     

重庆南川甑子岩山体崩塌机制研究

本文以重庆南川甑子岩崩塌为例,对近水平厚层状高陡灰岩山体座落滑移式崩塌机制进行研究,通过工程地质分析揭示了甑子岩危岩崩塌的成因机制,利用数值模拟开展了初始变形破坏的研究。研究认为,甑子岩崩塌是自然条件下形成发育、受岩溶风化与人类工程活动影响所产生的大型危岩体崩塌。岩体中多组大型陡倾节理发育,卸荷作用下在陡崖边缘形成张拉裂隙,地下水长期溶蚀使裂隙连通率不断增大,地下采空加速软弱基座破坏、危岩体变形。随着裂隙的贯通,软弱基座内部应力累积,应变逐渐增大,当超过岩体强度时发生圆弧形剪切滑移破坏,导致柱状危岩体座落崩塌。     

基于地面三维激光扫描的三峡库区危岩体监测

三峡水库周期性蓄水改变了岸坡内的地下水渗流场和应力场,降低岩土体的剪切强度,对库岸边坡、岩体稳定性影响很大。以往库区岸坡岩体形变监测主要通过设置固定点进行观测,难以发现岩体整体变化情况。地面三维激光扫描方法能获取岩体整体表面厘米精度的点云数据,具有无需接触目标、获取速度快、精度高等特点,非常适合库区高陡危岩体表面三维形变监测。以巫山箭穿洞危岩体为例,采用地面三维激光扫描方法对箭穿洞危岩体进行了为期2年（2017—2018年）共3期监测,以第一期观测目标周围稳定岩体数据为基准,对数据进行重叠点云迭代配准,点云配准精度优于±2.7 cm。针对箭穿洞危岩体在观测时段内的变化情况,构建危岩体区域的基准不规则三角网模型,以点到基准面最近距离法结合危岩体变化区间分析其变形。通过对比分析箭穿洞危岩体3期观测数据,发现相对于2017年,2018年箭穿洞危岩体左侧岩体有变形趋势;在库区蓄水阶段,危岩体局部多处存在明显凹陷变化,局部因蓄水影响发生约?0.03～?0.07 m变形。结果证明三维激光扫描技术在库岸高陡边坡形变监测中的有效性,为三峡库区高陡危岩体形变监测及地质灾害防治工作提供了参考。     

三峡库区黄南背西危岩体变形机理研究及失稳模式预测

自三峡库区2009年蓄水至175 m以来,库水位常年在高程145-175 m间波动,形成了高差30 m的水位变动带(消落带)。由于该变动带上岩体长期在饱和浸泡-风干曝晒的循环作用下,其物理力学强度不断减弱,于是大量的新生危岩和滑坡塌岸相继形成,此类地质灾害不仅点多面广,且破坏频率高,诱发因素甚多。本文以黄南背西危岩体为典型案例,基于影像资料、原位测试数据以及离散元数值模型深入分析了该危岩体未来失稳的破坏模式和变形成因机理,重点对该危岩体的应力场、形变场和基座岩体受水位作用影响展开研究。研究表明黄南背西危岩体发生失稳破坏的三种因素:1)底部岩体出现压溃破坏,2)底部破碎岩体受水影响劣化加剧,3)基座角砾岩岩体遇水水解。危岩体发生破坏将从其底部岩体出现压溃开始,上部岩体随后下错滑移,失稳岩体发生倾倒、滑移和坠落的复合型破坏。     

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.     

Report of the restudy of the defined global stratotype of the base of the Silurian System

The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs.     

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″.     

The Tendencies of the Development of the Mineral-Resources Sector at the Turn of the Century

Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base.     

Causes of the famine among the rural population of the Sahelian zone of the Sudan

Taking the example of W Sudan, an analysis of the climatic incidents leading to the two recent famine disasters is made. On this natural background, the human side is investigated. Focus is directed towards the fragile economic structure of the famine-prone population groups. An early-warning system for famine in the Sahelian Zone is proposed taking grain production and storage, livestock development and the relationship between the prices of livestock and grain as major indicators.     

东濮凹陷北部沙河街组三段中亚段沉积环境分析

东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。     

郯庐断裂南段研究进展与断裂性质讨论

据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。     

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.