三峡库区藕塘滑坡变形失稳机制研究

三峡库区藕塘滑坡是巨型顺层基岩古滑坡,滑坡面积1.78km2,体积约9.0107m3,威胁3900余人的生命财产安全,涉及场镇整体搬迁,同时对长江航道形成潜在堵塞隐患,是近年来三峡库区重大滑坡灾害之一。基于大量的现场地质调查及工程地质勘探,详细介绍了滑坡地质地貌及地质结构特征; 充分利用现场监测数据,深入分析了滑坡变形特征; 在此基础上,从地质成因和环境成因两方面对滑坡变形失稳机制展开系统研究,并结合滑坡稳定性计算对其变形发展的趋势进行了预测。相关的结论主要包括:(1)该滑坡具有多级多期次滑动特征,主要表现为三级滑动,且空间形态具有视向倾斜滑动的特征; (2)特殊的地形地貌、地层岩性及地质构造等因素是滑坡长期孕育形成的地质内因; (3)库水位周期性波动及集中降雨是诱发滑坡复活变形的环境外因,研究表明该滑坡变形与库水位下降及集中降雨的相关性显著; 库水位下降导致坡体内外地下水落差形成指向坡外的渗透压力,促进滑坡体变形; 集中降雨则增加滑坡体自重和下滑力,并使得大量的水富集于易滑软层,软化滑带土,促使滑坡蠕动变形加速; (4)三级滑坡体与西侧变形区在极端工况下存在欠稳定状态可能性,推断现阶段滑坡以局部失稳破坏形式为主。鉴于此,建议进一步加强监测,采取相应的工程防治措施。     

中等倾角岩层顺向坡滑坡发育特征及形成机制分析——以拖担水库左岸坝肩滑坡为例

中等倾角岩层顺向坡,受坡体结构和岩体物理力学性质控制,多存在变形、崩塌、滑坡等工程地质问题,常常会诱发大规模的地质灾害。该类斜坡潜在滑动面不直接出露地表,一般具有变形机制复杂、隐蔽性强和危害大的特点,是滑坡领域关注与研究的重点。拖担水库大坝左岸为一古滑坡,在水库扩建开挖过程中,诱发古滑坡体复活。在分析古滑坡工程地质条件的基础上,结合地质勘察和变形监测结果,研究了其变形特征及形成机制。研究结果表明:(1)左岸古滑坡具有岩层倾角"上陡下缓"、滑体底部存在反倾坡内的剪切破碎带、滑床岩体产生弧状弯曲的特点;(2)古滑坡体为一基岩顺层滑坡,滑动模式为"滑移(弯曲)—剪断"型,其变形破坏过程包括三个阶段:弯曲隆起阶段、滑移剪出阶段和扰动变形阶段;(3)该类斜坡变形破坏后,坡体易沿"上陡下缓"的椅型软弱层面发生二次滑动,滑坡控制关键是对下部变形区的保护。     

降雨诱发缓倾顺层滑坡机制离散元模拟

降雨在节理岩体的离散元模拟中有一定的局限性。文章提出一种等效渗流法模拟降雨条件下地下水向坡脚的渗流过程。以西南地区某顺层岩质滑坡为例,采用施加固定水头的方法,实现地下水在滑体内部的渗流过程,从而诱发滑坡形成。研究结果表明:(1)雨水入渗从坡顶向坡脚渗流,导致滑体内部空隙水压力升高;(2)斜坡受地下水渗流影响,坡脚首先发生变形并逐渐向上部呈阶梯状扩展。随渗流时间的延长,坡脚产生滑移,斜坡中上部和后缘出现拉裂,沿软弱夹层发生整体向河流方向滑动堆积形成堰塞湖;(3)滑坡形成的地质力学模式为"滑移-拉裂",滑体前缘运动至河流对岸形成前缘鼓丘,模拟结果与现场实际特征吻合。该方法可实现降雨条件下节理岩质斜坡中地下水渗流对滑坡形成的影响模拟。     

关键影响因子作用下三峡库区堆积层滑坡分布规律及变形破坏响应特征

三峡库区崩滑地质灾害频发,堆积层滑坡是最常见的滑坡类型。在分析三峡库区145处库岸堆积层滑坡资料基础上,选取地形地貌、地质岩性和斜坡构造作为控制因素、降水和库水波动作为主要诱发因素,探究堆积层滑坡在上述关键影响因子下的分布发育规律及变形破坏响应特征,阐明内在机理,结果表明:(1)受区域地质构造和基岩地层岩性显著控制,滑坡发育频次和规模沿长江存在显著空间差异性;(2)砂页岩夹煤层岩组(SC)和泥灰岩与砂泥岩互层岩组(MSM)对库区堆积层滑坡危害最大,软岩、“软-硬”互层二元结构和水-岩(土)相互作用是主导滑坡发育的主要影响因素;(3)大多数滑坡涉水,主要发育在10°~30°斜坡上,前缘高程集中在100~175 m,受库水波动影响严重,岸别和斜坡结构对堆积层滑坡发育没有明显控制作用;(4)库区滑坡主要由降雨-库水下降联合诱发滑体前缘滑移-拉裂,引发牵引式滑坡,降雨与库水波动各自对滑体的影响格局和程度存在明显差异。以期研究成果为有针对性的库区滑坡总体防治提供一定的科学指导。     

三峡库区大型斜倾顺层滑坡失稳机理分析——以石柱县龙井滑坡为例

长江三峡库区位于我国地形第二、三级阶梯过渡地带,地质环境复杂,斜倾顺层基岩滑坡较为发育。本文以重庆石柱龙井滑坡为例,详细分析了大型斜倾顺层基岩滑坡的变形特征、成因机理和破坏模式、并采用极限平衡法计算了滑坡在四种工况条件下的稳定性。结果表明:(1)龙井滑坡位于扬子准地台石柱向斜北西翼,体积约1.42×106 m3,主滑方向162°,前缘发育两个次级滑坡;(2)受地形地貌、地层构造、地下水和降雨等因素影响,滑坡目前处于蠕滑变形阶段,变形方式主要为拉张裂缝、剪切裂缝和局部鼓胀变形;(3)滑坡同时处于暴雨和前缘次级滑坡滑动条件下,稳定性为1.03,处于欠稳定状态,滑坡易沿软弱夹层发生整体滑动破坏。     

三峡大树场镇堆积层滑坡暴雨失稳机理研究

2014年9月1日,奉节大树场镇发生了大型崩塌堆积层滑坡,体积约37.8×104m3。基于大量的现场地质调查和室内分析,文章阐述了滑坡特殊的地质地貌及地质结构特征,分别从地质和环境因素两个方面进行了滑坡成因分析,采用非稳态非饱和渗流方法研究滑动失稳变形过程,并基于地貌学与工程地质力学理论推断滑坡形成演化过程。得出如下结论:(1)大树场镇滑坡为极端降雨诱发的近水平地层区崩塌堆积层滑坡,具有多次滑动特征;(2)特殊的地形地貌条件是滑坡形成的内因;极端强降雨是滑坡发生的直接诱发因素;(3)降雨前期,降雨主要通过入渗滑体增加其自重,入渗量大而渗流量小,对滑体稳定性影响较小;之后持续强降雨致使基岩顶面处的孔隙水压力不断增大,为滑体提供动态浮托力,加之滑体内部形成的渗流场导致稳定性大幅度降低;堆积体结构分布受控于基岩接触面形态,滑体不同区域达到饱和状态时间存在明显差异性是多次滑动变形破坏的理论依据;(4)短时极端降雨触发堆积层局部饱和岩土体由蠕滑逐步形成小规模滑坡碎屑流;持续极端降雨导致基岩顶面富集大量地下水,使堆积层岩土体呈饱和-过饱和状态,形成大规模滑坡碎屑流。     

甘肃永靖黑方台地区灌溉诱发型滑坡发育特征 及力学机制

水是诱发黄土滑坡最为积极的因素,以灌溉诱发型滑坡尤为典型.基于野外水工环地质综合调查,对黑方台地区灌溉渗透诱发滑坡的发育特征进行总结.通过分析特定孕灾地质条件下滑坡发育特征的差异,认为黄土滑坡形成的力学机制以滑移-压致拉裂-剪断型和蠕滑-拉裂-滑移型为主,而黄土-基岩滑坡以滑移-压致-拉裂型为主.滑移-压致拉裂-剪断型黄土滑坡为原位溯源后退扩展式,系灌溉水入渗后造成黄土饱和带厚度增大,不仅造成台缘周边地下水溢出带部位渗透压力增大,且抗剪强度显著弱化,从而在坡体自重作用下发生蠕滑剪切.锁固段突然破坏使滑坡快速启动,滑体冲击致早期饱水滑床产生液化,产生高位抛射,借助原始地形滑体加速运移形成高速远程运动.蠕滑-拉裂-滑移型黄土滑坡是黄土底部饱和带厚度较薄或灌溉入渗影响较小的地段,以后缘拉裂为主激发形成.渗灌溉水长期入渗造成下伏基岩顺倾泥岩层面软化泥化,从而在顺向坡段产生黄土-基岩顺层滑坡,该类滑坡以低速短程滑坡为主.     

三峡库区千将坪滑坡失稳探讨

千将坪滑坡是三峡水库二期蓄水到139m高程水位期间发生的特大型滑坡,也是三峡库区近年来发生的规模较大的滑坡,受到了多方面的关注。滑体物质组成包括上部为残坡积粘土夹碎石和老滑坡堆积体、下部为沙镇溪组泥质粉砂岩两部分,沿基岩软层顺层下滑。根据滑动特征,可划分为顺层滑动、切层剪出以及滑覆堵江和过江反冲区三个区。本文重点研究了降雨、水库蓄水以及组合因素下滑坡稳定性变化特征。在蓄水前自然状态下,整体稳定系数K=1.18。未蓄水时暴雨状态下,稳定系数K=0.97,与蓄水前自然状态下比较,稳定系数降低20.9%;仅考虑蓄水而未降雨时,滑坡的稳定系数K=0.99,与蓄水前自然状态下比较,稳定系数降低18.3%;在蓄水到134m 强暴雨状态下,稳定系数K=0.93,与蓄水前自然状态下比较,稳定系数降低24.8%。反映了蓄水和降雨二者的组合对滑坡失稳影响是非常明显的。     

三峡库区千将坪滑坡地质力学模型研究

三峡水库初次蓄水不久,千将坪即发生了特大型滑坡。通过对千将坪滑坡滑动区与影响区的勘察试验及对比研究,查明了千将坪滑坡的物质组成、结构及滑坡边界条件,分析了滑坡影响因素及其机制,建立了千将坪滑坡的地质力学模型。分析表明,千将坪滑坡为三峡水库水位上升与降雨联合诱发的水库新生型深层岩质滑坡,水库蓄水起主要和关键作用。     

云南彝良两河镇坪子滑坡成因及特征分析

2017年8月25日云南彝良县两河镇坪子村发生突发性滑坡,堆积体堵塞河道并形成两个堰塞湖。通过对滑坡现场进行详细的地质调查,结合无人机航拍手段,分析了滑坡成因及运动特征。结果表明:彝良坪子滑坡是在降雨不断渗流、孔隙水压力不断增大的作用下,岩土水理性质发生根本性变化,使得滑坡右侧顺层滑移,左侧沿断层带发生侧向剪切滑移,整体发生“楔形体”滑动,属典型的顺层平推式滑坡;“滑坡埂”的剪断是造成滑体骤然剧滑的根本,也是滑体中下部没有完全解体且保持一定结构特征的原因之一;滑坡经历了三次滑动,整个运动过程可概括为右侧顺层滑移—左侧“剪切滑移”—“滑坡埂”剪断、滑坡整体下滑—滑体“紧急刹车”以及堆积体“多次叠加堆积”。     

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.     

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″.     

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.     

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.     

On the consistency of proposed models for the Pyrenees with the structure of the eastern parts of the belt

The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time.