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31.
滑坡治理中格构锚固结构的解析解分析 总被引:17,自引:0,他引:17
在分析格构锚固结构受力的基础上 ,将格构梁简化为受集中力作用的弹性地基上的梁 ,提出了格构锚固结构的力学模型 ,利用 Winkler弹性地基上梁的解析解对格构梁进行了内力和变形的分析 ,发现格构梁的受力状况受弹性特征λ、梁格间距 ls以及悬臂长度影响 ;建议梁长 l与λ宜满足 lλ≥ 2π;采用较小间距的格构梁以及小吨位锚索 ,间距宜满足 lsλ<π/ 2 ,悬臂长度取 (0 .3~ 0 .5 ) ls,并将分析结论应用于三峡库区巴东太矶头东滑坡治理工程的设计中 相似文献
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三峡工程库区巴东县赵树岭滑坡稳定性与防治对策研究 总被引:16,自引:2,他引:16
赵树岭滑坡是三峡工程库区的重要滑坡,其稳定性直接关系到巴东新县城沿江大道的安全,并对新县城土地利用意义重大。在阐述赵树岭滑坡基本特征的基础上,运用水岩耦合三维有限元数值方法模拟了滑坡稳定性,预测了三峡水库蓄水后滑坡稳定性发展趋势和渗流特征。研究表明,水库蓄水及水位波动是影响滑坡稳定性的主要因素,三峡水库蓄水后,滑坡将发生局部失稳,必须加以治理,提出了滑坡防治的原则与对策。 相似文献
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The paper first recalls briefly a methodological framework to assess landslide hazard and risk analysis in terms of predisposition, triggering andrevealing factors. This framework, that reflects the mechanisms involved in the landslide, is based on the Geotechnical Characterisation of slope movements proposed by Vaunat et al. (1994) and Leroueil et al. (1996). The Geotechnical Characterisation can be schematized by a 3-D matrix having the following axes: types of movement; types ofmaterial; and the four stages of movement: pre-failure, failure, post-failure andreactivation. For each relevant element of this 3-D matrix, there is a characterisationsheet including: the controlling laws and parameters, the predisposition factors, thetriggering or aggravating factors, the revealing factors and the consequences of the movement. The paper focuses afterwards on the post-failure stage, which generallyis the most destructive, and on the mobility index. It is shown that this laterindex can be described as the product of sub-indices associated with failure, brittlenessof the material, ability of the soil to develop pore pressures, geometry of the moving soil mass and characteristics of the terrain. It is also shown how these aspectscan be incorporated into the Geotechnical characterisation of slope movements. This seems to provide a rational basis for examining slope movements at the post-failure stage and assessing associated risks. 相似文献
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Giant landslides are significant hazards associated with many active volcanic edifices. We describe a similar feature on ancient (>4 Ma) volcanic deposits subject to active tectonism. The landslide is approximately 3 km long by 1 km wide, with an estimated depth of 400 m. Side margins are straight and parallel, mimicking regional structure; narrow valleys incised down these margins provide low-strength side-release surfaces. Between these is a giant slump consisting of at least four, largely intact, discrete blocks that have moved down-dip a distance of >500 m. A series of flows with areal extents ranging from 0.01 to 0.5 km2 extends from the front of the failure. The materials represent an eroded sequence of andesite flows on the flanks of a stratovolcano. These have undergone two phases of hydrothermal alteration, and are deeply weathered to low-density (1040±80 kg m−3) silt (59%) and clay (35%) materials with strength properties typical of weathered silts (c=26±3 kN m−2; φ=42±8°). The size and location of this landslide preclude detailed geotechnical investigation of the failure. The worth of numerical stability analysis as an alternative technique in assessing the nature of the failure and hence the risk it poses to nearby communities is investigated. Sensitivity analysis identified likely conditions under which initial failure may have occurred: analyses for sensitivity to strength and earthquake acceleration needed conversion to critical combinations (F=1.0) of water table and strength/acceleration to remove the overriding influence of water table fluctuations. Failure was likely initiated either by a high water table level (83-84%), or some combination of intensity VII-IX earthquake waves together with water table heights of 40-80%. A general hazard assessment indicates that the risk associated with creep and catastrophic failure of the main mass is small, whereas the risk from flow failures near the toe of the landslide may be high. Important parameters (hydrological regime, flow failure morphology, age of initiation, and rates of movement) requiring closer investigation are identified. Development of a model is crucial to assessing the hazard associated with a feature such as that described here. With limited resources, a detailed stability analysis is a powerful tool as an initial stage in hazard analysis. 相似文献
36.
Evaluating Earthquake-Triggered Landslide Hazard at the Basin Scale Through Gis in the Upper Sele River Valley 总被引:6,自引:0,他引:6
To evaluate techniques for assessing earthquake-triggeredlandslide hazard in the Southern Apennines (Italy), a GIS-based analysis was used to modelseismically induced slope deformations. Geological, geotechnical, geomorphological and seismologicaldata were integrated into a standard earthquake slope stability model. The model assessed thelandslide potential that existed during the 1980 Irpinian earthquake in the Upper Sele river Valley.The standard Newmark displacement analysis, widely used for predicting the location of shallowunstable slopes, does not take into account errors and/or uncertainties in the input parameters.Therefore, a probabilistic Newmark displacement analysis technique has been used. Probabilistictechniques allow, e.g., an estimation of the probability that a slope will exceed a certain criticalvalue of Newmark displacement. In our probabilistic method, a Monte-Carlo based simulation modelis used in conjunction with a GIS. The random variability of geotechnical data is modelled by probabilitydensity functions (pdfs), while for the seismic input three different regression laws wereconsidered. Input probability distributions are sampled and the resulting values input into empiricalrelations for estimating Newmark displacement. The outcome is a map in which to each siteis related a spatial probability distribution for the expected displacement in response to seismic loading.Results of the experiments show a high grade of uncertainty in the application of the Newmarkanalysis both for the deterministic and probabilistic approach in a complex geological setting suchas the high Sele valley, quite common in the Southern Apennines. They show a strong dependence onthe reliability of the spatial data used in input, so that, when the model is used at basin scale,results are strongly influenced by local environmental condition (e.g., topography, lithology, groundwatercondition) and decrease the model performance. 相似文献
37.
David K. Keefer 《Surveys in Geophysics》2002,23(6):473-510
Post-earthquake field investigations of landslide occurrence have provided a basis for understanding, evaluating, and mapping the hazard and risk associated withearthquake-induced landslides. This paper traces thehistorical development of knowledge derived from these investigations. Before 1783, historical accounts of the occurrence of landslides in earthquakes are typically so incomplete and vague that conclusions based on these accounts are of limited usefulness. For example, the number of landslides triggered by a given event is almost always greatly underestimated. The first formal, scientific post-earthquake investigation that included systematic documentation of the landslides was undertaken in the Calabria region of Italy after the 1783 earthquake swarm. From then until the mid-twentieth century, the best information on earthquake-induced landslides came from a succession ofpost-earthquake investigations largely carried out by formal commissions that undertook extensive ground-based field studies. Beginning in the mid-twentieth century, when the use of aerial photography became widespread, comprehensive inventories of landslide occurrence have been made for several earthquakes in the United States, Peru, Guatemala, Italy, El Salvador, Japan, and Taiwan. Techniques have also been developed for performing ``retrospective' analyses years or decades after an earthquake that attempt to reconstruct the distribution of landslides triggered by the event. The additional use of Geographic Information System (GIS) processing and digital mapping since about 1989 has greatly facilitated the level of analysis that can applied to mapped distributions of landslides. Beginning in 1984, syntheses of worldwide and national data on earthquake-induced landslides have defined their general characteristics and relations between their occurrence and various geologic and seismic parameters. However, the number of comprehensive post-earthquake studies of landslides is still relatively small, and one of the most pressing needs in this area of research is for the complete documentation of landslides triggered by many more earthquakes in a wider variety of environments. 相似文献
38.
长江巨洪前期物理因子的配置 总被引:4,自引:4,他引:4
提出了长江巨洪前期物理因子配置的概念,在每一次巨洪发生之前,影响巨洪的主要物理因子之间一般都会表现出相似的特征,即出现一些固有的配置,这些配置正是长江发生巨洪的强信号,对长江巨洪的预测研究具有重要的指示作用。 相似文献
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