九龙县沃绰沟泥石流发育特征及防治措施

沃绰沟泥石流沟为九龙河左岸的一条支沟,位于四川省九龙县乃渠乡水打坝村沃绰沟组,流域面积7.29km2,主沟沟长4.51km,纵坡降416.9‰。。2011年9月26日九龙县沃绰沟暴发了泥石流,毁坏耕地,直接威胁13户60人的生命财产安全。在工程地质调查的基础上,分析了泥石流的基本特征,并计算了单沟泥石流危险度,对泥石流危险性进行了分析评价,该沟属于中度危险的泥石流沟。结合沃绰沟泥石流的发育特征,提出了防治方案。     

基于改进熵权法和云模型的泥石流易发性评价

为了解决在泥石流易发性评价过程中的随机性和模糊性的问题,选取了一次最大冲出量、泥石流发生频率、流域面积、主沟长度、最大相对高差、松散物源储量、泥砂补给段长度比、日最大降雨量、人口密度、植被覆盖率10个评价指标建立了基于正态云的评判模型。并以三条实测泥石流沟为例,对熵权法进行改进获取了各评价指标的权重,根据实测值利用正态云发生器得到评价指标的隶属度矩阵,再结合权重求得综合确定度,从而判断各条泥石流沟的易发性。     

松潘县叠台沟泥石流形成条件及其危险性分析

通过分析松潘县境内的叠台沟泥石流的形成条件,运用暴雨条件下降雨强度和渗透系数的比值法对沟道两侧物源的危险性进行了分析,使用单沟泥石流危险度评价方法分析该泥石流沟的危险性,结果表明该泥石流沟物源稳定性差,处于高度危险级别。     

云南本屋宅箐泥石流沟特征及危险性评价

文章以云龙县宝丰乡福利村本屋宅箐泥石流沟为研究对象,在现场实地调查的基础上,阐述泥石流沟特征、类型、成因、发展趋势,并对该泥石流沟的危险性进行了评价。该泥石流的形成受地质、地形、气象水文及人类活动等综合因素的影响,前期降雨使固体物质分散汇入沟床积累,属于崩塌+滑坡型、沟谷泥石型、中型、高频、发展期稀性泥石流。目前,福利村本屋宅箐流域固体物源丰富,降雨集中,水源充沛,溯源侵蚀作用强烈,物源区滑坡、沟岸坍塌发育,谷坡稳定性差,泥石流的发展有增强趋势。本次采用成都山地所刘希林于1996年提出的单沟泥石流危险度评价方法对该泥石流沟的危险性进行评价,单沟泥石流危险度H单=0604,按照分级标准,福利村本屋宅箐泥石流沟属高度危险泥石流沟。     

基于层次分析法的绵茂公路泥石流危险性评价

选取绵茂公路典型的徐家坝泥石流沟为例,运用层次分析法对其危险性进行建模和评价分析,主要从历史危险和潜在危险2个方面去考虑其危险性。依据该模型,得出的结果为历史危险性和潜在危险性各占比重为0.5,这与地质人员现场调查的结果一致。因此,该方法可以推广到绵茂公路其他泥石流沟的危险度评价中,为绵茂公路泥石流风险评估提供科学依据。     

未确知测度理论在东川泥石流危险性评价中的应用

将未确知测度理论应用到东川泥石流沟危险性评价中。根据实际工程地质条件,选取12个泥石流危险性影响因子作为评价指标,制定评价指标的危险性分级标准。根据未确知测度理论建立泥石流危险性评价指标的单指标测度函数,然后运用层次分析法计算各评价指标的权重,得到泥石流危险性的综合测度函数,最后使用置信度识别准则对泥石流危险性等级进行判定。将该方法应用于云南省东川地区12条泥石流沟,结果表明,该方法的判定结果比经典方法更符合实际,证明了该方法的合理性。     

基于BP神经网络的方法评价泥石流危险度

应用吉林省某地区8条泥石流沟资料,以主沟坡度、单位流域面积松散物源量、山坡坡度、流域切割密度、植被覆盖率、补给段长度六项为评价因子,采用BP神经网络的方法对文中的泥石流沟进行评价,发现BP神经网络的方法对研究泥石流危险度是合理并且相对简单的。     

基于层次分析法的水库区泥石流危险性评价研究

泥石流危险性评价是水库区工程地质内部评价的重要内容。本文以四川省雅砻江孟底沟水电站库区为背景,基于层次分析法,选取地层岩性、不良地质体密度、高程高差、降雨因子等11个影响因子,建立基于栅格单元的泥石流危险性评价体系图。在GIS平台上利用其强大数据处理功能,把泥石流危险评价由定性评价直观地展现为对泥石流危险性的定量评价。将泥石流危险性划分为四个等级,分别为轻度危险区、中度危险区、较高危险区和高度危险区。     

多宗隆哇泥石流风险评价

多宗隆哇泥石流沟位于青海省兴海县中铁乡,距茨哈峡水电站仅1km,流域面积为144.3km2,由于汇水面积大且物源较多,将对下游的茨哈峡电站造成威胁。运用泥石流风险评价理论,结合泥石流的危险度评价和易损度评价,综合多宗隆哇沟泥石流危险度评价(H单=0.50044)和灾害的易损度评价(V单=0.49),运用自然灾害风险度模型,得出了多宗隆哇沟泥石流的风险度为0.24,为中度风险泥石流沟。     

泥石流危险性三要素评估方法

泥石流作为一种山区常见的地质灾害,但由于泥石流孕育与形成的复杂性,至今对其发生的危险性进行准确预测还比较困难。通过对西南地区数十条已发生的泥石流沟实例进行统计分析,提出以雨强、坡降和物源三个基本要素作为评价泥石流危险性的依据,提出三要素的分级方法,并给出雨强、坡降和物源在评价泥石流危险性的赋值权重。在考虑泥石流沟堵塞情况给予适当修正的基础上,通过反演分析建立泥石流危险性大小的三要素评价方法,最后以大量的泥石流案例验证了该方法的合理性。     

Susceptibility assessment of debris flows using the analytic hierarchy process method——A case study in Subao river valley,China

Many debris flows have occurred in the areas surrounding the epicenter of the Wenchuan earthquake.Susceptibility assessment of debris flows in this area is especially important for disaster prevention and mitigation. This paper studies one of the worst hit areas, the Subao river valley, and the susceptibility assessment of debris flows is performed based on field surveys and remote sensing interpretation. By investigating the formation conditions of debris flows in the valley, the following assessment factors are selected: mixture density of landslides and rock avalanches, distance to the seismogenic fault, stratum lithology, ground roughness, and hillside angle. The weights of the assessment factors are determined by the analytic hierarchy process(AHP) method. Each of the assessment factors is further divided into five grades. Then, the assessment model is built using the multifactor superposition method to assess the debris flow susceptibility. Based on the assessment results, the Subao river valley is divided into three areas: high susceptibility areas, medium susceptibility areas, and low susceptibility areas. The high susceptibility areas are concentrated in the middle of the valley, accounting for 17.6% of the valley area.The medium susceptibility areas are in the middle and lower reaches, most of which are located on both sides of the high susceptibility areas and account for 45.3% of the valley area. The remainders are classified as low susceptibility areas. The results of the model are in accordance with the actual debris flow events that occurred after the earthquake in the valley, confirming that the proposed model is capable of assessing the debris flow susceptibility. The results can also provide guidance for reconstruction planning and debris flow prevention in the Subao river valley.     

Debris flow simulation 2D (DFS 2D): Numerical modelling of debris flows and calibration of friction parameters

Debris flows are rapid mass movements with a mixture of rock, soil and water. High-intensity rainfall events have triggered multiple debris flows around the globe, making it an important concern from the disaster management perspective. This study presents a numerical model called debris flow simulation 2D (DFS 2D) and applicability of the proposed model is investigated through the values of the model parameters used for the reproduction of an occurred debris flow at Yindongzi gully in China on 13 August 2010. The model can be used to simulate debris flows using three different rheologies and has a user-friendly interface for providing the inputs. Using DFS 2D, flow parameters can be estimated with respect to space and time. The values of the flow resistance parameters of model, dry-Coulomb and turbulent friction, were calibrated through the back analysis and the values obtained are 0.1 and 1000 m/s², respectively. Two new methods of calibration are proposed in this study, considering the cross-sectional area of flow and topographical changes induced by the debris flow. The proposed methods of calibration provide an effective solution to the cumulative errors induced by coarse-resolution digital elevation models (DEMs) in numerical modelling of debris flows. The statistical indices such as Willmott's index of agreement, mean-absolute-error, and normalized-root-mean-square-error of the calibrated model are 0.5, 1.02 and 1.44, respectively. The comparison between simulated and observed values of topographic changes indicates that DFS 2D provides satisfactory results and can be used for dynamic modelling of debris flows.     

Définition d'une typologie des dépôts de laves torrentielles et identification de critères granulométriques et géotechniques concernant les zones sources

The paper discusses viscous and saturated flows which can propagate at high velocity in torrent channels, referred to here as debris flows. Specific morphological, textural and sedimentological criteria have been identified, on which to distinguish debris flows from other torrent deposits. From a study of numerous debris flows sampled in 11 torrential catchment environments in the French Alps, two types of debris flows have been determined: those with a granular matrix and those with a cohesive matrix. Their typology is based mainly on the fraction of soil smaller than 20?mm although several discriminating particle size criteria have also been considered on the fraction between 20 and 200?μm. The author has selected five criteria for study, that relative to the fractions <50?μm being the most convenient. Geotechnical tests have also been used as a complementary criterion for this typology. The values of the Atterberg limits and blue methylene tests are generally lower for the debris flows with a granular matrix (Fig.?8a and Table?5). In most situations, the plasticity index of debris flow deposits is low. Both the soils sampled in the source areas and those mobilised as debris flows generally have particle size distributions and geotechnical characteristics similar to those of debris flow deposits reported in the literature. The paper concludes that source materials with a granular matrix are more likely to result in debris flows (as defined here) while the source materials with a higher fine fraction are more likely to move as mud flows.     

泥石流冲击力的野外测量

冲击作用是泥石流最为剧烈的一种破坏方式。泥石流的冲击力因此也成为泥石流工程防治和危险性分区中的重要参数。然而,由于其破坏力巨大,可靠的野外泥石流的冲击力数据比较少。2004年通过在云南蒋家沟建立的泥石流冲击力野外测试装置和新研制的力传感器以及数据采集系统,首次测得不同流深位置、长历时、波形完整的泥石流冲击力信号。原始信号经过低通滤波处理后,得到真实的泥石流冲击力数据。对数据的初步分析发现,在同等流速的条件下,连续流的冲击力要比阵性流的大得多。单就阵性流而言,泥石流的冲击力最大值也不是随流速而单调增加的,而应该跟它所携带的固体物质的大小有很密切的关系。最后,对不同位置的冲击力过程线的分析说明泥石流中中等粒径的石块多集中在龙头和流体表面,而大粒径的石块应该是在泥石流体中半悬浮运动。     

四川省某泥石流特征及危险度评价

从泥石流特征、发育条件及活动趋势等对某区泥石流灾害进行分析,并采用刘希林和唐川等学者于1996年提出的单沟泥石流危险度评价方法对该区泥石流的危险度作了定性定量评价。结果表明,危险度H为0.47,属中度危险。最后提出了相应的防治措施和建议。     

Une méthodologie d'analyse et de cartographie de l'aléa "initiation de laves torrentielles" – application au torrent du Bragousse (France)

Debris flows may result in personal injury or loss of life as well as damage to constructions. The economic consequences of such events are important, and likely to become more so with increasing urbanisation. In this paper, "debris flow" is defined as a viscous flow of saturated materials at high velocities of up to 20?m/s in channels. These materials have a high concentration of solids such that their dynamics may be considered at the interface between mechanical and hydraulic flow. The occurrence of a debris flow results from a number of interrelated factors including topography, geology, geomorphology and hydrogeology. The triggering factor is most often water, frequently a violent rainstorm. In order to identify the initiation mechanisms, it is necessary to have a knowledge of the environmental situation in the particular catchment area. Clearly, this will involve an understanding of: (1) the catchment area and its geological conditions; (2) the climatic characteristics of the locality and the nature of the materials in the source area; (3) the pattern of such events in the past. In order to obtain such an understanding, a dual approach of field and laboratory work was considered appropriate. Twelve catchment areas in the northern and southern French Alps were studied to assess the significance of the three aspects mentioned above. The study of numerous debris flow deposits sampled in these catchment areas suggested two types of debris flows: those with a cohesive matrix and those with a granular matrix. In the field, they were categorised on the basis of a morphological consideration of the area as well as according to the texture and grain size of the material in the flow. In the laboratory, granulometric tests were used. In addition, the granulometric and geotechnical characteristics of the source areas were compared with those of the debris flow materials. The grain size distribution appears to be an important factor in determining the likelihood that the source area materials would be moved by violent storms and from a debris flow. From tests undertaken on the <20?mm fraction, superficial deposits with between 16 and 40% of the particles of <50?μm seemed to be most likely to result in debris flows. This paper discusses the fieldwork undertaken from the upper catchment area down to the channel of a debris flow. Each mechanism is described with an analysis of the geological and topographical contexts, the extent of the movement and the hydrological processes that lead to the initiation of a debris flow. On the basis of this, maps have been produced to show the potential for the initiation of a debris flow. Five criteria were chosen to define the debris-flow hazard: (1) slope angle; (2) nature of the geological formation and hydrogeological characteristics; (3) slope erodability and instability; (4) grain size; (5) available volumes of superficial deposits present in the source area. These five indices form the global index. The maps show the spatial distribution of the hazard and can be useful in determining the most appropriate remedial/protective works to be undertaken in zones of the greatest risk.     

宝兴县和平沟泥石流基本特征及成因机制分析

和平沟为一老泥石流沟,历史上多次爆发泥石流。该沟流域面积15.90 km2,主沟长7.4 km,主沟平均纵比降208‰,松散固体物源总量为87.36×104m3,近期可能参与近期泥石流活动量约7.9×104m3。在有利的自然地质环境条件和人为因素相互作用下形成泥石流灾害。     

Landslide susceptibility mapping of the Sea to Sky transportation corridor, British Columbia, Canada: comparison of two methods

The Sea to Sky corridor stretches over a distance of 135?km into British Columbia’s Coast Mountains. The corridor has witnessed hundreds of historical and pre-historic landslides. In the last 154?years, 155 landslide events have been reported. The most common types of landslides are rockfalls and debris flows, which are small in volume, but can be quite damaging. These are more abundant in the southern part of the corridor where infrastructure is built close to steep slopes. Two different methods were adapted to create debris flow and rockfall/rock slide susceptibility maps. Both qualitative heuristic and fuzzy logic susceptibility maps showed a similar distribution of susceptibility zones, especially high susceptibility. Correlation of high susceptibility zones with occurrence of historical and mapped geological landslide events was very good. Success rate curves were calculated for extrapolated zones of initiation for debris flow and rockfall/rock slide deposits. Success rate curves were better for debris flow than rockfall/rockslide maps.     

5.12地震引发潜在泥石流灾害的调查评价——以四川省德阳绵竹市龙形沟泥石为例

"5.12"地震形成的滑坡崩塌为泥石流提供了丰富的固体松散物质,严重威胁到交通、民房和安置点等的安全[1、2],成为灾区重建的重大隐患。本文以四川省绵竹市龙形沟泥石流为例,讨论5.12地震引发潜在泥石流地质灾害的调查评价方法。龙形沟流域属高山峡谷地貌,呈叶状,支沟众多,主沟未暴发过泥石流,但"5.12"地震后,现场调查发现流域内多达9条支沟暴发了泥石流。本文针对该类潜在泥石流沟谷的特点,在野外工作的基础上,分析其易发程度和发展趋势,计算其容重、流速、流量和冲击力等特征参数,对该类潜在泥石流沟谷的调查和防治具有一定实际意义。