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411.
����InSAR�����Ļ����ֺ���� 总被引:2,自引:0,他引:2
????InSAR??????????????????????????????L???ε??????PALSAR??????????????????????????????????????????μ???????????????????????????????????????????2008-2010??7??ALOS PALSAR????????????????????????4???????????????????ε???·????????λ??????????λ??????????з??????????????????????????????????????????????л??μ??????????????????Ч????????? 相似文献
412.
413.
2014年鲁甸M_S6.5地震震前与同震滑坡空间分布规律对比分析 总被引:3,自引:3,他引:0
2014年8月3日,云南省昭通市鲁甸县发生了MS6.5地震,地震诱发了大量滑坡。文中以牛栏江沿线鲁甸县、巧家县和会泽县交界处面积为44.13km2的区域为研究区,开展地震震前与同震滑坡的空间分布规律对比分析。根据震前Google Earth高分辨率影像与震后0.2m分辨率的超高分辨率航片数据,分别建立了震前滑坡与同震滑坡数据库。结果表明,研究区内震前有284处滑坡,本次地震触发1 053处滑坡。借助10m×10m分辨率的数字高程模型(DEM)数据,基于GIS平台提取研究区的高程、坡度、坡向、曲率、岩性、烈度、河流共7个主要因子,并利用滑坡的面积百分比(Landslide Areas Percentage,LAP)和点密度(Landslide Number Density,LND)对比分析震前与同震滑坡的空间分布规律。结果表明,震前与同震滑坡的易发高程区间分别为1 200m与1 200~1 300m。坡度越大越容易发生滑坡,其中坡度10°的区域由于距离河流很近,也为滑坡易发区。震前与同震滑坡发育的优势坡向都是近S向。当斜坡为凹坡时(曲率值为负值),滑坡易发性较高。地震烈度越大,越易发生同震滑坡。灰岩夹白云质灰岩分布区很容易发生滑坡,玄武岩和火山角砾岩分布区在地震力的作用下边坡的稳定性也大大降低。震前、同震滑坡的发生与到河流的距离大致呈现正相关性。震前滑坡LAP的峰值大多数都与震前已经存在的大型滑坡有密切的对应关系。 相似文献
414.
How does forest structure affect root reinforcement and susceptibility to shallow landslides?
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Christine Moos Peter Bebi Frank Graf Josias Mattli Christian Rickli Massimiliano Schwarz 《地球表面变化过程与地形》2016,41(7):951-960
Forests can decrease the risk of shallow landslides by mechanically reinforcing the soil and positively influencing its water balance. However, little is known about the effect of different forest structures on slope stability. In the study area in St Antönien, Switzerland, we applied statistical prediction models and a physically‐based model for spatial distribution of root reinforcement in order to quantify the influence of forest structure on slope stability. We designed a generalized linear regression model and a random forest model including variables describing forest structure along with terrain parameters for a set of landslide and control points facing similar slope angle and tree coverage. The root distribution measured at regular distances from seven trees in the same study area was used to calibrate a root distribution model. The root reinforcement was calculated as a function of tree dimension and distance from tree with the root bundle model (RBMw). Based on the modelled values of root reinforcement, we introduced a proxy‐variable for root reinforcement of the nearest tree using a gamma distribution. The results of the statistical analysis show that variables related to forest structure significantly influence landslide susceptibility along with terrain parameters. Significant effects were found for gap length, the distance to the nearest trees and the proxy‐variable for root reinforcement of the nearest tree. Gaps longer than 20 m critically increased the susceptibility to landslides. Root reinforcement decreased with increasing distance from trees and is smaller in landslide plots compared to control plots. Furthermore, the influence of forest structure strongly depends on geomorphological and hydrological conditions. Our results enhance the quantitative knowledge about the influence of forest structure on root reinforcement and landslide susceptibility and support existing management recommendations for protection against gravitational natural hazards. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
415.
Ali M. Rajabi M. Khamehchiyan Mohammad R. Mahdavifar V. Del Gaudio 《Soil Dynamics and Earthquake Engineering》2010
Arias intensity is considered as a shaking parameter suitable for characterizing earthquake impact on ground stability. Within the framework of a study aimed at providing tools for the assessment of hazards related to earthquake-induced slope failures, Arias intensity attenuation relations were determined for the Zagros Mountains region, an active tectonic belt elongated NW–SE in the western and south-western part of Iran. The calculation of relation coefficients was based on strong-motion data of earthquakes located in the Zagros area and recorded by Iranian stations managed by the Building and Housing Research Center of Iran (BHRC). Five models of attenuation relation were considered and their coefficients were estimated through a least-square regression analysis. The relations obtained were then applied to a data sample different from that used for regression and the root mean square (RMS) of residuals was examined in order to compare effectiveness of different relations in probabilistic estimates. Furthermore a comparison made with attenuation relations obtained for Alborz and the central part of Iran showed significant differences possibly related to structural differences. 相似文献
416.
中国西部地区典型岩质滑坡机理研究 总被引:25,自引:2,他引:23
中国西部具有独特的地域地质环境和活跃的内外动力地质条件。在这样的背景下,崩滑地质灾害十分发育,给人类居住环境及重大工程建设带来极大威胁和重大的损失。阐明这些灾害的形成机理,尤其是大型滑坡的发生机理,对灾害的防治具有重要的理论及现实意义。根据作者在中国西部地区多年的研究工作实践,对几类典型的大型岩质斜坡变形及失稳机理进行了较为深入的分析,重点阐述了这些大型滑坡形成的地质条件、斜坡变形过程及发生机理
的"概念模型",其中包括滑移-拉裂-剪断的三段式模式、挡墙溃决模式、"超级强夯"模式等。这些机理及模式的提出,对这一地区的防灾减灾实践具有一定的指导意义。 相似文献
417.
Landslide risk evaluation and hazard zoning for rapid and long-travel landslides in urban development areas 总被引:8,自引:6,他引:2
Kyoji?SassaEmail author Gonghui?Wang Hiroshi?Fukuoka Fawu?Wang Takahiro?Ochiai Masanori?Sugiyama Tatsuo?Sekiguchi 《Landslides》2004,1(3):221-235
Risk evaluation for earthquake-induced rapid and long-travel landslides in densely populated urban areas is currently the most important disaster mitigation task in landslide-threatened areas throughout the world. The research achievements of the IPL M-101 APERITIF project were applied to two urban areas in megacities of Japan. One site is in the upper slope of the Nikawa landslide site where previous movements were triggered by the 1995 Hyogoken-Nambu earthquake. During detailed investigation, the slope was found to be at risk from a rapid and long-travel landslide induced by sliding surface liquefaction by earthquakes similar in scale to the 1995 event. A new plan to prevent the occurrence of this phenomenon was proposed and the plan was implemented. Another area is the Tama residential area near Tokyo. A set of field and laboratory investigations including laser scanner, geological drilling and ring-shear tests showed that there was a risk of sliding surface liquefaction for both sites. A geotechnical computer simulation (Rapid/LS) using the quantitative data obtained in the study allowed urban landslide hazard zoning to be made at individual street level. 相似文献
418.
419.
Observation of shear zone development in ring-shear apparatus with a transparent shear box 总被引:1,自引:1,他引:1
Using a new ring-shear apparatus with a transparent shear box and video image analysis system, drained and undrained speed-controlled tests were conducted on coarse-grained silica sands to study the shear-zone formation process in granular materials. Velocity distribution profiles of grains under shear at various stages in the ring shear tests were observed through processing the video image by the Particle Image Velocimetry (PIV) program. Shear-zone thickness and type of shear mode (slide-like or flow-like) during shear were observed. Before reaching peak strength in low-speed and drained condition test, a comparatively major part of the sample in the upper shear box showed a velocity distribution profile of structural deformation and dilatancy behavior. After peak strength, the velocity profile changed into a slide-like mode and thereafter showed almost no change. In higher speed tests with drained and undrained conditions, an almost slide-like mode was observed, compared to low-speed test. Apparent shear-zone thicknesses of high-speed tests are thinner than low-speed tests. Unexpectedly, almost no difference was observed in the shear-zone thickness and mode of shear (slide or flow-like) between drained and undrained tests. This study was conducted as part of the International Programme on Landslides (IPL) M101 “Areal prediction of earthquake and rain induced rapid and long-traveling flow phenomena (APERITIF)” of the International Consortium on Landslides (ICL). These results will contribute to understanding the mechanism of shear-zone development in granular materials as a basic knowledge for disaster risk mitigation of rapid long run-out landslides. 相似文献
420.
L. Caballero J. L. Macías A. García-Palomo G. R. Saucedo L. Borselli D. Sarocchi J. M. Sánchez 《Natural Hazards》2006,39(1):103-126
In September 1998 tropical storm “Earl” swept southern Mexico, producing intense rainfall in the states of Oaxaca and Chiapas.
Among the most devastated cities was Motozintla, located in the drainage basin of the Allende, La Mina and Xelajú Grande Rivers.
The rainfall from the tropical storm totaled 175 mm on September 8 and 130 mm on September 9, duplicating in two days the
average monthly precipitation in the region. Numerous landslides occurred in the vicinity of Motozintla, depositing large
volumes of material into the Xelajú Grande stream. Much of this sediment was subsequently remobilized, yielding debris flows,
hyperconcentrated flows, and sediment-laden flows that inundated most sections of Motozintla city. The flows covered an approximate
area of 3.15 km2 with a minimum volume of 4.4 × 106 m3 of sediment. Communication of Motozintla with the rest of the Chiapas State was interrupted for about a month, as was the
supply of potable water, food, electricity, and fuel. The geologic record around Motozintla indicates that the Xelajú Grande
River has been a pathway for similar large floods during the last 6000 years. The oldest deposit yielded a radiocarbon age
of 5320 ± 100 14C years. B.P. At least two historic floods have occurred during the last 100 years, a time period defined by a stratigraphically
distinct tephra of 1902. Frequency analysis of the historical record of daily rainfall in the Motozintla area suggests that
events like that of September, 1998, have a recurrence interval of about 25 years. After the catastrophic flows of 1998, the
mitigation measures by Municipal Authorities were made without regard to geological and environmental factors, or to taking
into consideration the flow magnitude and appropriate hazard-mitigation techniques, with the result that Motozintla remains
at serious risk for future floods. Unfortunately, prior to the publication of this study, in early October 2005, Motozintla
was seriously damaged again by intense rain provoked by Hurricane Stan. 相似文献