蓄水和水位变动对三峡库区崩塌滑坡的影响及对策

在前人相关研究的基础上,选择三峡工程库区20处典型崩塌、滑坡体进行分类研究,分析三峡水库蓄水时和蓄水后,由于水位变动所产生的各种作用力,以及这些作用力可能给库区的崩塌、滑坡体带来的影响.在此基础上对库区崩塌、滑坡体的稳定性进行评价预测,认为浸水和水位急剧升降是影响水库崩塌、滑坡体稳定性的主要因素,并依此提出一些防治对策.     

Earthquake losses due to ground failure

Ground shaking is widely considered to be the primary cause of damage to structures, loss of life and injuries due to earthquakes. Nonetheless, there are numerous examples of earthquakes where the losses due to earthquake-induced ground failure have been significant. Whereas ground shaking causes structural and non-structural damage, with associated loss of function and income, ground failure is less likely to cause spectacular structural collapses, but is frequently the cause of major disruptions, particularly to lifelines, which can lead to prolonged loss of function and income, even for undamaged areas.Those involved in earthquake loss modelling are currently presented with three choices with respect to the incorporation of ground failure: they can choose to ignore it, assuming that any estimation of losses caused by shaking would effectively subsume the impact of these secondary hazards; they can include ground failure in a simple manner, using published approaches based upon qualitative data and a large degree of judgement; or, they can opt for a detailed site- or region-specific assessment of damage due to ground failure, with the associated time and expense.This paper presents a summary of the principal features of earthquake losses incurred in damaging earthquakes over the last 15 years. Survey data are impartially analysed, considering both ground failure and ground shaking as sources of damage, and their relative contribution to overall damage in each section of the regional infrastructure is presented. There are many other variables influencing these contributions, including the size of the earthquake, the economic status of the affected region, local geology and terrain and the building stock, which have been considered.The findings of the study are discussed from the point of view of loss modelling and which components of a model should merit the most time and resource allocation. The general assumption that ground shaking is the principal cause of damage and loss is strongly supported by the study. However, there are a number of scenarios identified where the failure to appropriately include the effects of ground failure would lead to unrealistic loss projections. Such scenarios include the assessment of building losses in small zones rather than on a regional basis, and the incorporation of lifeline damage or disruption and indirect losses into a model.     

Radon emanation from giant landslides of Koefels (Tyrol,Austria) and Langtang Himal (Nepal)

The identification of extremely high indoor radon concentrations in the village Umhausen (Tyrol, Austria) initiated a scientific program to get information about the source and distribution of this noble gas. The high concentrations can not be related to U anomalies or large-scale fault zones. The nearby giant landslide of Koefels, with its highly fractured and crushed orthogneisses, are the only possible source of radon, despite the fact that the U and Ra content of the rocks is by no means exceptional. The reasons for the high emanation rates from the landslide are discussed and compared to results gained from a similar examination of the giant landslide of Langtang Himal (Nepal). The exceptional geologic situation in both cases, as well as the spatial distribution of different concentration levels, indicate that both landslides must be considered as the production sites of radon. Independent of the U and Ra contents of the rocks, the most important factors producing high emanation rates are the production of a high active surface area and circulation pathways for Rn-enriched soil air by brittle deformation due to the impact of the landslidemass.     

Geology as a control on landslides on the Isle of Wight: an overview

The Cretaceous and Palaeogene sedimentary rocks that crop out on the Isle of Wight are highly prone to landsliding and the island offers an important field laboratory wherein to investigate a number of the different types of failure. Many of these landslides represent a significant engineering hazard, with several urban areas requiring remedial work and planning constraints (e.g. The Undercliff and Seagrove Bay) to aid development. Previous studies have thoroughly investigated the major landslides in the Undercliff area around Ventnor and presented a mechanism for that massive failure. This overview of the landslides throughout the Isle of Wight by the British Geological Survey was completed as part of the multidisciplinary survey of the surface geology, structure, geophysical response and offshore interpretations of the island between 2007 and 2010. The survey has collected new observational data on the extensive coastal landslides, as well as the distribution, nature and mechanism of failure of the lesser-studied inland examples.     

Geomorphic studies of landslides in the Tully Valley, New York: implications for public policy and planning

On April 27, 1993, a large landslide in the Tully Valley, Onondaga County, NY, destroyed three houses and resulted in the evacuation of four others; it also triggered a loss of potable drinking water for about 15 homes north of the slide area and affected a total of 20 ha of land. In the 7 years following this slide, several studies have been conducted by federal and state environmental agencies and by local universities. The goal of these investigations has been to determine what caused this slide, document the history of past landslides in the region, and establish whether future slides are likely to occur. This paper reports on the results of these investigations and examines their effect on the Tully Valley community.     

特大规模滑坡遥感调查──巧家县城滑坡

目视解译１：６７万彩红外航空象片发现巧家县城斜坡显示为典型的滑坡地形。经实地验证及结合地质资料、航空象片、卫星象片综合解译分析认为：根据斜坡形态、金沙江异常弯道、斜坡上松散物质分布及所处地质环境与降雨条件确定巧家斜坡为－巨型古滑坡，估算体积约１２０×１０８ｍ３，就我们所查阅到的国内外报道中为一最大规模古滑坡，年龄约１０万年。目前，滑坡整体已经稳定，但后壁、侧壁及滑体上发育的大量次生崩塌、滑坡、泥石流还将长期活动。     

Susceptibility analysis for slides and rockfall: an example from the Northern Calcareous Alps (Vorarlberg, Austria)

In this paper a tool for semi-quantitative susceptibility assessment at a regional scale is presented which is applicable at areas with complex geological setting. At a study area within the Northern Calcareous Alps geotechnical mappings were implemented into a Geographical Information System and analysed as grid data with a cell size of 25 m. The susceptibility to sliding and falling processes was considered according to five classes (very low, low, medium, high, very high). Susceptibility to sliding was analysed using an index method. The layers of lithology, bedding conditions, tectonic faults, slope angle, slope aspect, vegetation and erosion were combined iteratively. Dropout zones of rockfall material were determined with help of a Digital Elevation Model. The movement of rolling rock samples was modelled by a cost analysis of all potential rockfall trajectories. These trajectories were also divided into five susceptibility classes. The susceptibility maps are presented in a general way to be used by communities and spatial planners. Conflict areas of susceptibility and landuse were located and can be presented destinctively.     

金沙江溪洛渡地区灾害第四系特征及对工程的影响研究

通过溪洛渡地区１∶２．５万区域地质调查获得的第一手系统资料的综合分析,论述区内地质灾害事件所形成的第四系（本文简称灾害第四系）——滑坡堆积、堵江堰塞堆积和泥石流堆积的特征,首次确认区内堵江堰塞堆积的存在,并结合工程实际对灾害第四系的稳定性进行评价。     

Geomorphological characteristics and slope processes associated with different basins: Mallorca (Western Mediterranean)

We compare the different geomorphological processes which occurred in Pliocene–Quaternary times on two very similar slopes in Mallorca, one located at the Tramuntana Range and the other in the Llevant Ranges. Both slopes have the same geological structure, the same stratigraphic and lithological levels, and the same altitude and orientation. The different slope processes are due to the relationship between the accommodation space and the sedimentation rate in the adjacent basins: In the Valencia Trough (located N of the Tramuntana Range), the sedimentation rate has not been sufficient to fill the accommodation space, whereas in the Alcudia Basin (adjacent to the Llevant Ranges), the sedimentation rate has been sufficient to fill the accommodation space. This difference has resulted in major landslides on the Tramuntana slope, whereas the Llevant slope is characterized mainly by alluvial fans and debris screes.