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1.
查明浅表部地层地质条件,对多层及高层建筑均至关重要。针对目前上海地区,在运用小螺纹钻孔进行浅表部工程勘察中存在的一些问题,就其如何合理使用,作了若干方面的探讨。 相似文献
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舟山大陆连岛工程西堠门大桥为一主跨跨度1 650 m的悬索桥,其北塔位于海中的老虎山上。老虎山四周临空,山体单薄,缓倾坡外裂隙构成边坡稳定的潜在底滑面,尽管塔基所在工程边坡整体稳定,但浅表部存在不稳定块体。本文对浅表部边坡进行了在最不利工况下的定量计算和分析,并提出对边坡所在最低海水位以上浅表部岩体进行框架梁锚索和锚杆加固方案,加固后工程边坡稳定性系数都在1.5以上,满足工程安全要求。 相似文献
3.
某跨海大桥主塔位工程边坡稳定性研究 总被引：5，自引：0，他引：5
某跨海大桥为一悬索桥 ,其主塔位于海中的岛礁上。因岛礁山体略显单薄 ,受数条断层及其他构造裂隙的影响 ,整体完整性较差。本文在大量现场地质资料调查基础上 ,系统结合上部结构荷载、风荷载 ,对工程边坡稳定性进行了分析研究 ,结果表明工程边坡整体稳定 ,但浅表部存在不稳定块体 ,并提出浅表部边坡相应的加固建议措施 相似文献
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基于西南地区10个大型水电工程95点空间应力测试数据与50点硐壁应力恢复法测试数据,统计分析了边坡地应力场随垂向、水平向深度变化规律,根据主应力量级、倾角变化规律分析边坡浅表部地应力场特征,探讨了西南深切峡谷地区边坡地应力场分布规律。研究表明,（1）边坡应力场在宏观上可划分为浅表部区(0～300 m)与深部区(>300 m);（2）浅表部区主应力量级、倾角波动较为剧烈,而深部区主应力量级、倾角较为稳定,其最大主应力介于15～30 MPa,中间主应力介于10～20 MPa,最小主应力介于5～12 MPa,最大、最小主应力倾角介于0°～30°,最大主应力约为最小主应力的1.5～3.5倍;（3）浅表部区地应力场具有由主应力较小、最大主应力倾角与坡角近平行转变为主应力急剧增高、最大主应力倾角变化不明显,继而转变为主应力量级、最大主应力倾角剧烈波动,最后逐渐转变与深部应力场近于一致的特征。 相似文献
5.
文章以四川省石棉县鸡公山斜坡为例,首先基于现场调查和物探方法确定裂隙网络模拟有效尺寸,然后采用MonteCarlo法对岩体裂隙连通率和强度参数进行裂隙网络模拟,研究结果表明:裂隙连通率与裂隙发育特征以及裂隙优势方向与斜坡夹角之间有着密切关系。斜坡浅表部强风化带岩体在不同的方向,其裂隙连通率在0~98%之间,对应的岩体内聚力在0.16~2 MPa之间,内摩擦系数在0.62~1.5之间。最后得到鸡公山斜坡浅表部强风化带岩体强度参数:C=0.2 MPa,f=0.7。研究成果证实了裂隙的发育特征对岩体的力学性能以及可能的失稳破坏方向有重要的影响。 相似文献
6.
元谋变质核杂岩及其控矿作用 总被引：3，自引：0，他引：3
元谋变质核杂岩构造系统由核部杂岩、拆离断层下盘韧性剪切带、拆离断层以及上盘拆离滑脱系四大部分构成。研究表明：核部杂岩控制了本区与基性－超基岩、花岗岩有关的Cu，Pt，Pb，W，Mo及稀土等矿床；韧性剪切带与后期浅表部的脆性断层控制了本区Au，Cu等矿产的产出；主折离断层、次级折离断层与后期浅表部的脆性断层构成一个集导矿、储矿为一体的构造系统，共同控制了折离滑脱系中Pb，Cu，铂铜镍、赤（磁）铁矿及部分非金属矿的产出。本文结合Lister的混合流体模式，元谋变质核杂岩的成矿机理，指出本区矿产勘查远景及方向。 相似文献
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挽近期以来,伴随青藏高原的强烈隆升,中国西南地区河谷经历强烈、快速下切,形成西南地区所特有的高山峡谷地貌,在此过程中,河谷岸坡分别遭受垂向剥蚀与侧向卸荷作用,出现一系列浅表生结构面,将岸坡浅表部岩体切割成大小不等块体,在后期时效变形过程中以崩塌、滑坡形式失稳破坏。本文以崩塌体发育部位,堆积物岩性、块度大小、风化特征等研究为基础,结合岸坡河谷演化、构造演化历史分析,追溯形成崩塌的地形地貌、地层岩性、风化卸荷、岩体结构等河谷岸坡特征。通过上述分析,总结归纳产生崩塌的主控因素是地形地貌、岩性与岩体结构,在地形地貌适合、浅表生作用强烈的区域,岸坡岩体变形破坏也较强烈,崩塌堆积物也较发育。 相似文献
10.
泥质海岸带浅表地层沉积序列区域地质调查方法 总被引：4，自引：1，他引：4
天津市淮淀乡幅(1∶50000)浅表地层沉积序列地质调查提供了深覆盖区区调的新方法。即用浅表钻孔代替地质点,对近现代沉积物组合进行分类,判释沉积环境变化,结合年代地层学,建立浅表地层沉积序列。采用浅表地层沉积序列地质图的形式,展示测区浅表地层与近现代地质环境演化及人类活动的影响,为经济建设和决策提供直观、内涵丰富的地质资料。 相似文献
11.
Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414. 相似文献
12.
New biostratigraphical data based on foraminifers, algae and pseudo-algae indicate that the limestone pebbles of the channelized polygenic conglomerates of the Migoumess formation contain Late Visean (V3bγ–V3c) assemblages. That confirms the Westphalian age attributed to this formation by Hollard [Zdt. Geol. Ges. 129 (1978) 495–512]. The Tournaisian age assigned to it by palynology [C. R. Acad. Sci. Paris, série II 310 (1990) 1573–1576] cannot be retained. The Tirhela formation, Late Visean and Serpukhovian (E1) in age, is coeval with the Akerchi formation [Berkhli, thèse d'État, 1999; Berkhli et al., J. Afr. Earth Sci. (accepté)]. The Idmarrach formation, mapped as a thrust sheet [C. R. Acad. Sci. Paris, série II 310 (1990) 1573–1576], is dated as Serpukhovian (E1) and its thrusting is consequently post-Serpukhovian. Palaeogeographic and geodynamic consequences are listed. To cite this article: M. Berkhli, D. Vachard, C. R. Geoscience 334 (2002) 67–72 相似文献
13.
Laurent J. Michot Frédéric Villiéras Michèle François Isabelle Bihannic Manuel Pelletier Jean-Maurice Cases 《Comptes Rendus Geoscience》2002,334(9):611-631
The aim of this review is to examine the present knowledge about water structure close to an interface or confined in porous spaces. First, the structure of liquid water is briefly described. Though its understanding remains incomplete, it appears that it is largely dominated by the hydrogen bond network and its dynamical evolution. The presence of any ‘foreign’ substance in water perturbs such a structure by changing at least locally the hydrogen bond network. For this reason, the presence of a solid interface significantly modifies the structure of the first adsorbed layers. Whatever the support, it is now clearly evidenced that structural perturbations are limited to distances lower than 10–15 Å from the interface. The nature, energetic heterogeneity and hydrophilicility/hydrophobicity of the solid surface influence the arrangement of water molecules. This surface organisation must definitely be considered when studying adsorption phenomena at the solid–aqueous solution interface. The relevance of such problems to geosciences is illustrated by a few situations in which water structure plays a prominent role. To cite this article: L.J. Michot et al., C. R. Geoscience 334 (2002) 611–631. 相似文献
14.
本文描述了产于吉林中部的皱纹珊瑚1新属2新种。这些珊瑚化石除具皱纹珊瑚的一般特征之外,还具有六射珊瑚的特点。它对研究六射珊瑚与皱纹珊瑚之间演化关系具有重要意义。 相似文献
15.
Sedimentologic study of carbonated sediments of the Rmah-I member (Coniacian–Santonian) of Jabal Abtar, central southern Palmyrides (Central Syria), uncovers phosphatic levels, associated with marine vertebrate remains, that give evidence of an early episode of the Senonian phosphatogenesis in the Palmyrides. Sedimentary sequence analysis reveals a gradual marine transgression during the Senonian. Phosphatic sedimentation occurred in a shallow neritic marine environment almost connected with the open sea. Condensed sedimentation could have contributed to the phosphatogenesis. To cite this article: A.K. Al Maleh, N. Bardet, C. R. Geoscience 335 (2003). 相似文献
16.
El Hassane El Arabi José Bienvenido Diez Jean Broutin Rachid Essamoud 《Comptes Rendus Geoscience》2006,338(9):641-649
The Middle Anisian has been palynologically characterized for the first time, at the whole Moroccan scale, in the High Atlas of Marrakech. The stratigraphic, tectonic and paleogeographic implications of this discovery are analysed. To cite this article: E.H. El Arabi et al., C. R. Geoscience 338 (2006). 相似文献
17.
Inter-regional correlation of transgressions and regressions in the Cretaceous period 总被引：1，自引：0，他引：1
T. Matsumoto 《Cretaceous Research》1980,1(4):359-373
Well investigated platforms have been selected in each continent, and the history of Cretaceous transgressions and regressions there is concisely reviewed from the available evidence. The factual records have been summarized into a diagram and the timing of the events correlated between distant as well as adjoining areas.On a global scale, major transgressions were stepwise enlarged in space and time from the Neocomian, via Aptian-Albian, to the Late Cretaceous, and the post-Cretaceous regression was very remarkable. Minor cycles of transgression-regression were not always synchronous between different areas. Some of them were, however, nearly synchronous between the areas facing the same ocean.Tectono-eustasy may have been the main cause of the phenomena of transgression-regression, but certain kinds of other tectonic movements which affected even the so-called stable platforms were also responsible for the phenomena. The combined effects of various causes may have been unusual in the Cretaceous, since it was a period of global tectonic activity. The slowing down of this activity followed by readjustments may have been the cause of the global regression at the end of the Cretaceous. 相似文献
18.
The litho- and biostratigraphy of the Craie de Villedieu Formation (Coniacian-Santonian)of western France are described in detail. The formation is subdivided into three members each containing a number of lithologically distinct named hardgrounds and marker beds. These constitute an onlapping sequence that thins from > 15 m in the NE around Cangey and Villedieu-le-Château, to < 2 m in the SW around St Michel-sur-Loire, a distance of 70 km. Thickness variation is related to the interaction of differential subsidence with eustatic transgression. Comparison with the Chalk Rock Formation of southern England indicates that transgressive and regressive hardground suites may be differentiated on bed geometry and hardground surface characteristics. The Craie de Villedieu rests everywhere on a regional hardground that coincides with the Turonian/Coniacian boundary in expanded successions, but probably marks a significant hiatus. South-west of Tours, onlap results in Santonian strata resting disconformably on strata of Turonian age. The basal Craie de Villedieu contains a succession of three Coniacian ammonite faunas characterized by Peroniceras and Forresteria (Harleites) (oldest), Gauthiericeras margae (Schlüter), and Protexanites (youngest). Volviceramus ex gr. involutus (J. de C. Sowerby) occurs with the two uppermost ammonite assemblages. A Santonian ammonite fauna dominated by Placenticeras polyopsis (Dujardin) occurs with Texanites gallicus Collignon and common Cladoceramus in the middle of the formation. Cordiceramus ex gr. cordiformis (J. de C. Sowerby) is recorded with Santonian ammonites in the upper part of the formation. A correlation with the Micraster zones of chalk facies is suggested, based on the inoceramid stratigraphy. The record of T. gallicus in association with Cladoceramus affords the first direct evidence for the position of the base of the Santonian in the Anglo-Paris Basin. 相似文献
19.
R. A. Reyment 《Cretaceous Research》1980,1(4):299-327
The first trans-Saharan epicontinental transgression began in the Late Cenomanian and peaked in the Early Turonian. The sea entered through rifts (Nigeria) and subsiding areas (north Africa) and, at maximum extent, spilled out onto stable craton. The central Sahara was land in late Early Turonian time; the sea seems to have remained in the central part of the Benue rift, to sally forth again during the minor Coniacian transgressive pulse. The Coniacian transgression went no further than eastern and central Niger Republic. For a short time during the Cenomanian-Turonian link-up between the Tethys and the South Atlantic, some organisms (mainly ammonites and pelecypods) passed across the Sahara. The Coniacian marine deposits of eastern Niger contain several elements typical of the Mungo River Formation of Cameroun, and coastal Nigeria. These faunistic indications imply that the topographical obstacle formed by the Zambuk ridge of northeastern Nigeria was swamped at maximum transgression. A third, very extensive epicontinental transgression began in latest Campanian time and reached its acme in the Early Maastrichtian. In the central Sahara, at least, there was a retreat of the sea in later Maastrichtian times. A final transgression peaked during the Paleocene, after which the sea withdrew permanently from the northwest African hinterland. The same marine ostracod associations occur in the Paleocene of coastal Nigeria, the Sokoto embayment, Mali and Libya, thus providing strong evidence of a marine connexion, albeit brief, between the South Atlantic and the Tethys, despite the lack of outcrop evidence in the crucial Niger valley region. 相似文献
20.
Summary The Lower Lias Clay at Blockley, 20 km due south of Stratford-upon-Avon, UK, is thought to be representative of this clay formation over much of the Severn Basin. As far as the mineralogy of the clay is concerned, illite is the dominant clay mineral, kaolinite being subsidiary, with quartz, calcite, pyrite and chlorite/vermiculite present in subsidiary or accessory amounts. Weathering changes the mineralogy, with illite being degraded and calcite and pyrite being removed. Furthermore free iron oxide coatings become important as a result of weathering, with the maximum concentrations being present in the highly weathered material.The unweathered clay possesses a preferred orientation associated with turbostratic structures. At certain horizons microfolding and remoulding occurs in the unweathered clay and silty layers are displaced. Weathering has progressively destroyed the micro-structures present in the weathered clay horizons.The fissures in the Lower Lias Clay occur in five uniplanar sets. In the unweathered clay the intensity is fairly constant but it increases in a narrow zone just below the weathered horizons. The number of curved fissures also increases at this depth. This intense fissuring continues into the lowest zone of weathered clay where weathering is confined to the fissure surfaces. Fissures become less apparent in the more weathered horizons as more and more degradation has taken place. However, new smaller fissure systems are developed in the weathered clay, as are desiccation cracks.Engineering index properties and values of shear strength are given. Relationships between moisture content and strength, liquid limit and iron (Fe) content were observed, and a relationship between weathering zones and the shear strength-depth curve was established. 相似文献