Abstract: In this article, a laboratory-built experimental system laser-induced breakdown spectroscopy (LIBS), is used to measure soil samples. It explores landslides band soil of five typical landslides in Xiangxi (sic) River Section of the Three Gorges Reservoir area, which include Bazimen (sic) landslide, Baijiabao (sic) landslide, Jiajiadian (sic) landslide, Sixiangxi (sic) landslide and an unnamed landslide...
Abstract: Abundant burrows of Skolithos linearis, Palaeophycus tubularis, and Taenidium barretti are preserved in the Upper Devonian Donghe sandstone of Tarim basin, China. They are commonly highlighted in core by the color of the burrow fill in contrast to the surrounding matrix and have different textures and fabrics from the matrix. There are three kinds of calcite cements in burrows, microcrystalline-crystalline calcite cement, mosaic calcite cement, and ferroan calcite cement. Microcrystalline-crystalline calcite cement is widely distributed in the lower part of the Donghe sandstone, but it is rare in burrows filling. It displays a globule structure under burial cementation and seldom replaces the quartz grains in shallow burial depth stage. Mosaiccalcite cement is widespread in the Donghe sansdtone reservoir of North Tarim basin. It shows chrysoidine, orange and bright orange luminescence, and intensely replaces the quartz grains, forming in early diagenetic and shallow burial depth stage. Ferroan calcite is asymmetrically distributed in the Donghe sandstone reservoir of Central Tarim basin. It fills the remanent pores in the shape of mosaic and replaces the quartz grains, matrix, and early calcite cement, forming in late diagenetic and deep burial depth stage. The burrows filled with white calcite cements have low oil saturation or may be oil-stained. In contrast, there is high oil saturation in the sandstone reservoir where the bioturbation is sparse or not present. With increased bioturbation, the porosity, permeability, and oil saturation decrease; thus, bioturbation intensity and reservoir property appear to be negatively correlated.
Abstract: This study focuses on the determination of the age and provenance of a Precambrian unit on the southwestern margin of the Tarim craton, collectively known as the Ailiankate (埃连卡特) Group and Sailajiazitage (塞拉加兹塔格) Group, which were previously referred to as Paleoproterozoic-Mesoproterozoic. Zircon U-Pb LA-ICP-MS dating of chlorite quartz schist and tuff that form the Ailiankate Group and Sailajiazitage Group have yielded age peaks at 780 and 787 Ma, respectively. These data indicate that the Ailiankate and Sailajiazitage groups are Neoproterozoic succession deposited at ca. 740–790 Ma. Those strata are temporally equivalent and are likely parts of a single wide spread succession and reflect a rifting process related to the break-up of the Rodinia supercontinent. In situ zircon Hf isotopic data from Sailajiazitage Group show that older zircons (~1 994 Ma) have crustal model ages of 2 272–2 784 Ma, suggesting an ancient crustal growth and reworking. The ~787 Ma zircons have ~2 000 Ma crustal model ages, suggesting derivations from recycled Paleoproterozoic material.
Abstract: Holocene palaeoweathering conditions and environmental changes of Loulan (楼兰) Stupa Section were reconstructed by major elements analysis results and optical stimulated luminescence dating results. Major element results show source rock change little, with the composition equivalent to granodiorite. The low R value and high CIA (chemical index of alteration) value indicating the section at primary weathering phases. The muddy silt and silty clay have low R value and high CIA value and total iron content. In contrast, the sandy clay silt and sandy silt have high R value and low CIA and total iron value. Deglaciation time climate was relatively humid. In comparison to previous and posterior hiatus, the Middle-Holocene climate was relatively wet but still displayed high-frequency and high-amplitude fluctuations.
Abstract: Diatom stable isotope analysis offers considerable potential in palaeoceanography, particularly where carbonate material is scarce or absent. However, extracting pure diatom frustules free of external labile organic matter from marine sediments is an essential requirement for their applications as paleoenvironmental proxies. Here, based largely on previous work, we developed a method including physical separation and chemical oxidation steps to concentrate and clean pure large diatoms from laminated diatom mat and diatomaceous clay sediment samples for their stable isotope analysis. Using the physical separation techniques consisting of the removal of carbonate and excess organic matter, sieving, differential settling, and heavy liquid floatation, pure diatoms can be successfully isolated from the sediment samples with opal concentration more than 10%. Subsequent time oxidation experiment shows that labile organic matter coating pure diatom valves can be effectively removed with 30% H2O2 at 65 ℃ for 2 h. Measurements of δ13C after every step of physical separation demonstrate that contaminants and lost diatoms can influence the original diatom stable isotope signal, highlighting the importance of a visual check for dominant diatom size in the initial sample and purity in the final sample. Although the protocol described here was only applied to diatom mats or diatom oozes containing large diatoms (Ethmodiscus rex), we believe that this method can be adapted to common diatoms of general marine sediment samples.
Abstract: This article gives a description of our first study on ground rotational motion and its preliminary results. The ground rotational motions around vertical axis were obtained using near-field translational records of a temporal seismic array with observational distances of 1.8 to 2.7 km. The sources used are explosions with explosive of 500 kg for each. Ground rotational velocities were calculated using the space derivatives of the horizontal components of translational velocities from the array. The peak ground rotational velocities (PGRV) are approximately 30 to 57 μrad/s. Our results are very close to those from Wassermann et al. (2009), who used both a seismic array and a rotational sensor to record an explosion in Germany and obtained PGRV values of about 50 μrad/s. Their explosives are 150 kg, only one third of ours, but their observational distance is 250 m, much less than ours.
Abstract: The analysis of educts has become an important aspect for the security evaluation of hydraulic construction. Brown, white-based colloidal educts appeared in the left drainage corridors of the dam over the Yangtze River after its 5-year operation, which did not happen in the initial investigation. In this article, the physics characteristics of the educts were affirmed, and the analysis results of the major and trace elements among educts and the corresponding location of water samples, core samples, indicate that educts are the products from the chemical potential erosion of the dam foundation rock. Brown educts are uncertainties Fe and Mn-based materials, mainly derived from the corrosion of the chlorite and biotite, which may be caused by the changes of the oxidizing condition. White educts mainly with Si and Ca are derived from the corrosion of the calcite, feldspar, and partly invalidation of foundation curtain. Additionally, similarities of the chondrite normalized rare earth element (REE) patterns between educts and bedrock further illustrate homologous, and Ce and Eu anomalies relative to chondrite reflect changes of the water environment condition.
Abstract: To evaluate the reliability of a landslide in a reservoir, the universal transfer coefficient method, which is popularized by the Chinese standard, is adopted as performance function in this study for: (1) common deterministic method stability evaluation; (2) reliability evaluation based on a Monte Carlo method; (3) comparison of landslide reliability under different water levels and under different correlation coefficients between soil shear strength parameters (c, Φ), respectively with mean, standard deviation, reliability coefficient and failure probability. This article uses the Bazimen (八字门) landslide, which is located at the outlet of Xiangxi (香溪) River in the Three Gorges Reservoir, as an example to evaluate its stability and reliability under different water levels with two-dimensional deterministic and probabilistic methods. With the assumption that constant mean and normal distributed shear strength parameters (c, Φ), correlation coefficient ρc, Φ=−1 based reliability analysis, compared with ρc, Φ=0 and 1, indicates obviously more increase of reliability index and lower standard deviation as water levels rise. To the case of a certain water level, ρc, Φ=−1 does not have constantly positive or negative effects on landslide reliability compared with ρc, Φ=0 or 1, but is associated with water level. Whereas the safety factor Fs by deterministic method, which is almost the same value as corresponding mean of safety factor from probabilistic analysis, will increase slightly as water level increases.
Abstract: Taking hundreds of pieces of hazardous geological maps (1: 10 000) of Three Gorges reservoir area (3GR) as background, we establish regional three-dimensional (3D) geo-hazard model using DEM (digital elevation model) superposed surface images and geo-hazards elements. Based on landslides and other geo-hazard survey data, using improved B-REP (boundary representation) entity data structure (two-body 3D data structure), we set up 3D solid models for each hazardous bodies in each hazardous geological maps. Then we integrate the two types of 3D models with different scales from area to point, which are the regional geo-hazard 3D model and the solid models of each disaster body, in order to provide a visual processing and analysis platform for danger partition, stability evaluation, disaster prevention and control, early warning and command.
Abstract: In this article, a laboratory-built experimental system-laser-induced breakdown spectroscopy (LIBS), is used to measure soil samples. It explores landslides band soil of five typical landslides in Xiangxi (香溪) River Section of the Three Gorges Reservoir area, which include Bazimen (八字门) landslide, Baijiabao (白家堡) landslide, Jiajiadian (贾家店) landslide, Sixiangxi (泗乡溪)landslide and an unnamed landslide that has already slipped. Soil samples of the five landslides are taken in different latitudes, and in relatively consistent altitude. Through experimental measurement, the authors get spectrum of those soil samples, and then do qualitative and quantitative analyses of elements (Mg, Si, K, Al, etc.) in them. The authors conclude that main metal elements in the soil change according to different longitudes and latitudes, which opens up a new way of thinking for the quantitative analysis of the function of soil and water, and for the establishment of relations between chemical environment factors and soil engineering mechanics effects.
Abstract: The Kashmir earthquake 2005 (magnitude MW 7.6) triggered thousands of mass movements in northern Pakistan. These mass movements were mainly rock falls, debris falls, rockslides and rock avalanches. The mass movements vary in size from a few hundred cubic meters up to about 100 million cubic meters estimated for the Hattian Bala rock avalanche, the biggest one associated with this earthquake. This mass movement, which moved in southeastern direction, created two natural dams on the valley bottom and blocked the water ways of the Karli and Tung tributaries of the Jhelum River. Topographic, lithologic and structural information were used to investigate the Hattian Bala rock avalanche. Geotechnical and structural maps were prepared to understand relationship between geology and structure of Hattian Bala rock avalanche. The geometry and failure mode of this rock avalanche are controlled by southeast plunging synclinal structures, lithology, a bedding parallel slip surface and a pre-existing old rockslide. The structural map shows that the mass movement failure was due to Danna and Dandbeh synclinal structures plunging southeast on the hanging wall block of the reactivated Muzaffarabad fault. The slip surface of the mass movement followed the bedding planes along mudstone, claystone and sandstone surfaces. The mass movement perfectly followed the pre-existing synclinal morphology of the Danna and Dandbeh synclines.
Abstract: The transient response to longitudinal impact of flexible rods with Hertz contact is closely related to the extent of deformations with different impact parameters. By means of LS-DYNA, for different radius and different speeds, the longitudinal impact of a hammer with a rounded end on a drill rod is numerically simulated in this article. Simulations demonstrate that there is an obvious difference between analytical solution and numerical solution on condition of short curvature radius. In the circumstance contact pressure increases, the boundary of the yield zone exceeds that of the contact zone, and the significant plastic deformation reduces the intensity of contact pressure pulse. Contact force-time curves in loading and unloading phases shift down. The numerical solution is in good agreement with analytical solution on condition of large curvature radius and impact speeds. The deformation of yield region is constrained by the surrounding elastic region and no significant plastic deformation appears.
Abstract: High cut slopes have been widely formed due to excavation activities during the period of immigrant relocation in the reservoir area of the Three Gorges, China. Effective reinforcement measures must be taken to guarantee the stability of the slopes and the safety of residents. This article presents a comprehensive method for integrating particle swarm optimization (PSO) and support vector machines (SVMs), combined with numerical analysis, to handle the determination of appropriate reinforcement parameters, which guarantee both slope stability and lower construction costs. The relationship between reinforcement parameters and slope factor of safety (FOS) and construction costs is investigated by numerical analysis and SVMs, PSO is adopted to determine the best SVM performance resulting in the lowest construction costs for a given FOS. This methodology is demonstrated by a practical reservoir high cut slope stabilised with anti-sliding piles, which is located at the Xingshan (兴山) County of Hubei (湖北) Province, China. The determination process of reinforcement parameters is discussed profoundly, and the pile spacing, length, and section dimension are obtained. The results provide a satisfactory reinforcement design, making it possible a signficant reduction in construction costs.
Abstract: Detecting the timing and amount of deformation is critical for understanding the physical causes and eventually warning of possible landslide hazards. Monitoring of deformation of structures and ground surface displacements during landslides can be accomplished by using different types of systems and techniques. Besides geotechnical or physical techniques, remote sensing techniques can be classified as satellite techniques, photogrammetric techniques, geodetic techniques, ground based techniques, and so on. To study and govern growing geological disasters in China, especially in the Three Gorges area, Three Gorges Research Center for Geo-hazard (TGRG) is establishing an infra structure to effectively and comprehensively analyze the mechanism of landslide deformation, focused on the Huangtupo landslide, using of various advanced monitoring systems and techniques. In this article, the framework and latest advances of integration of multi remote sensing techniques in the infrastructure are presented. Different remote sensing techniques, data processing and integrating methods, and the latest results are discussed in detail. At last, reviews on current work and suggestions for further work are put forward.