Landslide phenomena in the area of Pomarico (Basilicata–Italy): methods for modelling and monitoring

This paper takes into consideration landslide phenomena in the clayey slopes facing the built-up area of Pomarico which is situated in the southern part of the “Fossa Bradanica”, in Basilicata (Italy). Based on the great number of geologic, geomorphologic and historic informations a geotechnical model of the slope was built. Particular attention has been paid to define the geotechnical parameters of the soil and which mechanical models are to be used. The studies point out a correlation between the water level in the detritus cover and the stability condition of the slope showing that phenomena at first located at the foot of the slope spread quickly towards its summit as the piezometric height increases.     

Évolution thermique des séries sédimentaires de la Marge ardéchoise : étude pétrographique de la matière organique et des argilesThermal evolution of the sedimentary series of the Ardèche Margin: petrological studies of organic matter and clays

Two wells, Balazuc (BA1) and Morte-Mérie (MM1), located in a confined area (1200 m apart) and separated by the Uzer fault (a Liassic structure with a dip fault of 1300 m) were analysed using conventional methodologies and techniques (PRV, TAI, XRD, STEM) in order to compare the diagenetic evolution of clays and organic matter. The thermal convective process allows the circulation of hot fluids and the oxidation of organic matter. The conductive process allows the maturation of the organic matter, the expulsion of hydrocarbons and the deposit of pyrobitumes in the migration channels. To cite this article: L. Martinez et al., C. R. Geoscience 334 (2002) 1021–1028.     

Influence de la microporosité sur le piégeage du gaz dans un milieu poreux naturel

Trapped-gas content in natural porous media, also called residual gas saturation (Sgr), corresponds to the imbibition end-point. To define the parameters controlling Sgr, two parameters were studied: the influence of rock characteristics (on 400 sandstone samples) and initial gas saturation (Sgi), on the basis of 60 experimental curves between Sgr and Sgi. Based on an extensive experimental database, this study establishes the dominant influence of microporosity on trapped gas saturation, and indirectly that of the contained clays. To cite this article: K. Suzanne, J. Billiotte, C. R. Geoscience 336 (2004).     

Rare earth element studies of surficial sediments from the southwestern Carlsberg Ridge,Indian Ocean

The rare earth element (REE) contents of sixteen surficial calcareous sediments from the southwestern Carlsberg Ridge, Indian Ocean, have been determined. The total REE vary from 35 ppm to 126 ppm and are inversely related to the calcium carbonate content. REEs show a strong positive correlation with Al + Fe + K + Mg + Na (r ²= 0.98) and Mn + Fe + Cu + Ni (r ²= 0.86) suggesting that the REE is associated with a combined phase of clays (mainly illite) and Mn-Fe oxyhydroxides. The aeolian input into these sediments is suggested from the weak positive Eu/Eu* anomaly. Shale-normalized (NASC) pattern along with La_(n)/Yb_(n) ratio suggest enrichment of heavy REE (HREE) relative to the light REE (LREE) with a negative Ce/Ce* anomaly implying retention of a bottom water REE pattern. An erratum to this article is available at .     

Significance of molecular-level behaviour incorporation in the constitutive models of expansive clays – a review

Expansive clays are widely prevalent all over the world as one of the most problematic soils. These soils undergo significant volume change with a change in the moisture regime, thereby posing problems to the stability of the structures founded on such strata. Efforts have been made to model the erratic behaviour of these soils at the macro, micro, and, to a lesser extent, nano levels. Micro and nano level fabrics, believed to have a central role in the overall behaviour of expansive clays, are only partially considered in the modelling concepts; natural clay fabrics with multiple clay minerals, silt and sand inclusions, micro fissures, cementation, overconsolidation, induration and other such features have never been considered. This paper covers a review of deficiencies in the existing constitutive models for the expansive characteristics of the natural clayey soils at macro, micro and nano levels. These shortcomings are discussed in the light of the understanding of the fundamentals including fabric and structure controlling the swelling mechanism of the expansive clayey soils at the molecular level. Finally, a framework based on authors’ work to incorporate molecular level behaviour in the constitutive modelling of expansive clays is presented.     

海洋粘土的组成及性能测试

为了海洋粘土的开发利用,对东太平洋中国大洋调查区的所有采集样品进行了粒度分析。结果发现粘土沉积物的粒度明显细小;通过红外光谱测试可将沉积物分为八个矿物组合类型,其中以粘土沉积物类型为主,且粘土矿物含量较高;吸水率测试结果证明海洋粘土具有较强的吸水性;典型海洋粘土样品的理化性能测试结果表明,与地表粘土相比,海洋粘土的膨胀容、胶质价、阳离子交换量及吸蓝量都相对较低;X射线衍射结果显示,海洋粘土的结晶程度明显偏差。综合分析海洋粘土的结构特征及理化性能,认为其活性比地表同类粘土大,预示着海洋粘土将会有更好更广的用途。     

Microfabric, chemical and mineralogical study of Indian marine clays

Marine clay deposits are encountered in the coastal regions of the world. They are soft in consistency with low shear strength and are highly compressible. The properties of these deposits are complex and diverse, and they mainly depend on the minerals present and microstructural arrangement of constituent particles. In the present investigation, the physico-chemical properties of the sediment samples obtained from marine deposits of east and west metropolitan coastal cities of India are discussed, and the test results obtained are compared with the synthetic samples such as bentonite and kaolinite. Mineralogical and fabric studies were carried out using scanning electron microscopy and x-ray diffraction techniques. Several consolidation and strength tests were carried out to study the engineering behaviour of these deposits. The strength and compressibility (Cc) values of these deposits varies from 27 to 45 kN/m² and 0.37 to 0.81 respectively. XRD studies confirm the presence of highly compressible clay minerals such as smectite, vermiculite, chlorite and traces of the low swelling mineral, kaolinite. The fabric studies indicate that the constituent particles were arranged in an open network, or flocculated structure resulting in a high void ratio.     

Sedimentology and stratigraphy in the cave Hamnsundhelleren,western Norway

The stratigraphy in Hamnsundhelleren is as follows. A basal weathered rock bed of unknown age is followed by laminated clay deposited under stadial conditions and correlated with palaeomagnetism to the Laschamp excursion (43–47 000 yr BP). Angular blocks, bones and clay above this are ¹⁴C dated to the Ålesund Interstadial (28–38 000 yr BP). Another stadial laminated clay following the Ålesund Interstadial includes a palaeomagnetic excursion correlated with Lake Mungo (28 000 yr BP). The newly discovered Hamnsund Interstadial above this consists of frost-weathered clay and scattered angular blocks. It is ¹⁴C dated to 24 500 yr BP on bones mixed into the Ålesund Interstadial. The Hamnsund Interstadial is succeeded by another stadial laminated clay and then a Late-glacial–Holocene mixture of bones and blocks. In Hamnsundhelleren and other similar caves four successive phases of sedimentary environments for each ice-free–ice-covered cycle have been identified: (i) ice-free phase (deposition of bones and frost-weathered blocks); (ii) subaerial ice-dammed lake phase (sand or silt deposited in a lateral glacial lake); (iii) subglacial ice-dammed lake phase (cave closed by ice, deposition of till, debris flows and laminated clay); (d) ice-plugged phase (cave is plugged by frozen lake water and/or glacial ice, no deposition).     

Zn-粘土催化剂对染料废水的O3氧化降解性能的影响

对于生物难降解性有机染料废水,用矿物催化剂进行复合催化氧化获 得了比较理想 的实验处理效果。以粘土为载体加载金属锌氧化物制成的可重复使用的固体催化剂,对人工模拟的染料废水进行复合催化臭氧氧化实验,获得了满意的效果。该法进一步提高了臭氧的降解效果,降低了处理成本。     

含铝多孔粘土材料的合成与研究

本文利用XRD、TEM等方法初步研究2：1型蒙脱石矿物及1：1规则间层的累脱石矿物与聚合羟基铝交联剂的层间交联作用，比较了不同制备条件下对形成含铝多孔粘土材料孔结构性质的影响。结果表明，适当增加Al／土值，采用PVA表面活性剂对粘土进行修饰改性有利于形成具有大孔结构的材料。