滑坡转化泥石流起动的人工降雨试验研究

滑坡转化泥石流起动的人工降雨试验研究是把握滑坡转化泥石流过程和机制的重要研究手段。选择泥石流典型流域——云南蒋家沟上游泥石流形成源地的弯房子和下游泥石流堆积地的大凹子沟口分别进行野外人工降雨原型试验。通过对全流域泥石流形成背景的考察来确定典型坡度、土体特征和植被条件等因素，从而选定试验地点。共实施了8场野外人工降雨下滑坡转化泥石流起动试验。采用国内外较为先进的试验设备和观测手段，实时监测了试验过程中土体特征参数的变化，包括土体水势、体积含水量、孔隙水压力和温度等，并录相观测试验过程中发生的现象。通过初步分析发现，泥石流宽级配砾石土具有以下特征：（1）在强降雨下，滑坡转化泥石流的起动机制是振动软化或液化；（2）土体破坏时可能处于饱和状态，也可能处于非饱和状态，试验结果并不支持饱和液化机制；（3）在泥石流源地试验时，部分试验的水势曲线在下降过程中表现出短时间的剧烈波动现象，表明土体破坏过程中存在土体强度的降低和恢复的交替过程：（4）土体破坏过程中存在能量交换；（5）在强降雨下，滑坡启动与泥石流形成是一个连续过程，土体破坏过程中表现出了泥石流的特征。     

降雨条件下滇西典型土质滑坡渗流特性分析

降雨是诱发滇西土质滑坡灾害的主要因素,选择滇西红层典型土质滑坡——思铺滑坡做深入的调查,考虑降雨入渗的影响,基于饱和-非饱和渗流理论,利用有限元方法,对强降雨条件下思铺滑坡地下水渗流场动态进行了数值模拟,得到了滑坡地下水压力水头、总水头变化、流速的变化规律,为滑坡的稳定性分析和滑坡预测提供重要的分析数据。     

桂北山区泥石流形成及发生成因分析——以灌阳县仁合村泥石流为例

泥石流是最为常见的山区地质灾害之一,是降水在向斜沟或背斜坡上形成的一种含有大量细颗粒、粗颗粒或砾颗粒等坚硬物质的特殊流体。泥石流具有同发性、周期性及群发性等灾害特征。泥石流的成因分析是预防及治理泥石流灾害的根本。以桂北山区灌阳县仁合村委蒋家屯泥石流为研究对象,结合现场详细勘察数据,基于地形地貌、岩性、地质构造、气象条件等多方面分析该处泥石流发生的原因。结果表明,陡峭的地形、松散的岩性、断裂带的作用、古滑坡造成的堰塞湖以及短时间强降雨都是造成该泥石流发生的主要因素。     

基于GIS的流域地质灾害危险性区划及评价

2010年8月13日,遭受"5·12汶川特大地震"重创的极重灾区绵竹清平发生强降雨,引发多处泥石流、滑坡、崩塌等地质灾害。其中以黄水河流域最为突出,导致漆树沟、花梯子沟内厂矿企业、居民生活和交通严重受损。本文通过现场调查和航空影像解译,分析黄水河小流域地质灾害的成因机制,在灾害学理论指导下,结合专家经验,通过对层次分析、信息量、统计量等模型的比较,利用GIS平台建立了泥石流、崩塌、滑坡灾害易发性、危险区划评价分析系统。应用该系统对震后地区棉竹清平等地区分别展开了泥石流、滑坡、崩塌灾害危险性区划研究,并取得了较好的成果。     

南水北调西线一期工程泥石流研究及其他山地灾害现状

南水北调西线一期工程区地处青藏高原东部,特殊的地质、地貌、土壤、植被、气象、水文等自然条件决定了该区属山地灾害易发区。受自然因素控制和人类活动影响,崩塌、滑坡、泥石流等山地灾害较为发育。主要山地灾害有滑坡、崩塌、泥石流、危险边坡及大型堆积体;其次为山洪、水土流失、冻融土流、路基塌陷等。通过实地考察、现场灾害填图、GPS定点、室内航片判读和TM,SPOT卫星图像解译,探讨了南水北调西线一期工程区泥石流的分布特征、规律及其他山地灾害的现状,初步分析预测了泥石流的发生规模(峰值流量、一次泥石流流出总量),尝试性地探讨了泥石流堵塞主河(堵河高度、回水范围)及其可能发生的二次灾害的定量分析方法,在此基础之上初步探讨了山地灾害对工程可能造成的影响与危害。     

汶川震区北川五星沟暴雨泥石流灾害调查

汶川地震诱发形成了大量高位崩滑坡地质灾害,为泥石流的形成提供了丰富的物源。震后每年均产生多起泥石流灾害,造成严重的经济损失和人员伤亡。通过调查2008年9年24日因暴雨引发的五星沟泥石流基本特征,讨论了泥石流物源堆积过程、活动特征、强度,预测了震后地震灾区泥石流发展趋势,为震后泥石流研究提供了典型实例,对地震灾区泥石流防治工作具有指导意义。     

滑坡堵江成坝的形成演进机制及危险性预测方法研究进展

近年来，频发的地震活动和极端天气诱发了大量滑坡堵江，严重威胁所在流域人民生命财产和基础设施安全，而目前对滑坡堵江成坝的形成演进机制认识仍不够全面，值得进一步深化研究。梳理21世纪以来典型的滑坡堵江案例，分析其中危险性较大的堰塞坝形成的一般过程和主要特征；针对大型的岩体滑坡堵江，分别从理论分析、物理模型试验和数值模拟方法 3个方面揭示其成坝的必要条件和堵江过程的流固耦合细观机制；提出滑坡堵江危险性预测的3阶段：即堵江状态预测、堰塞坝稳定性预测和溃坝危险性预测等。通过全面梳理堵江危险性预测3阶段研究成果发现，堵江状态预测参数和标准选取尚没有统一形式，堰塞坝稳定性评价尚未考虑坝体材料和结构等特征，溃坝危险性预测的数学模型物理机制仍有待进一步揭示。基于当前研究存在的局限性，凝炼滑坡堵江研究未来应重点关注的4个问题：(1)考虑碎裂化过程的崩滑体堵江堆积结构及成坝预测模型；(2)滑坡堵江成坝演进过程的物理和数值模拟方法；(3)基于滑坡物源状态的堵江危险性评价方法与风险评估；(4)堰塞坝临灾预警因子及监测预警关键技术。研究成果为高山峡谷地区滑坡堵江灾害链预测、堰塞坝应急抢险地质处置及区域防灾减灾规划...     

基于理论分析和FLAC3D的滑坡稳定性评价及治理

以徐州市鼓楼区的沙虎山滑坡为研究对象,分析了滑坡的形成条件和影响因素,对其进行稳定性评价和数值模拟。通过简单平面滑动分析计算出滑坡在自然状态下和长时间降雨形成软弱夹层状态下的稳定性系数,并结合FLAC~(3D)数值模拟方法,分析滑坡的位移及应力分布情况。研究结果表明目前沙虎山滑坡处于稳定状态,但由于存在软弱地层,长期降雨可能会诱发滑坡灾害。经综合分析后提出了治理方案。     

北京洪水峪泥石流形成条件探讨

洪水峪泥石流、沟内崩塌、不稳定斜坡等不良地质现象发育。该沟内煤矸石、沟道物源丰富,上游汇水面积大,沟道纵坡降较大,在强降雨沟道径流冲刷作用下,极易发生揭底起动而形成泥石流灾害。在雨季,支沟常有少量泥沙、块石冲出,阻塞进山道路,淤塞河道,引起原有坝体损毁,威胁居民生命财产安全。通过对以往资料的综合整理,结合现场调查,对洪水峪泥石流形成的诸多条件进行了分析,以期对该区泥石流的防治与预测起到参考作用。     

汶川县太平驿沟泥石流的形成机制及危险性分析

2010年8月14日强降雨过程导致汶川震区太平驿沟泥石流沟暴发泥石流,造成较大经济损失,且近几年雨季多次爆发规模不等的泥石流。由于该灾害点位于汶川地震震中附近地区,是地震与降雨共同作用下的结果,研究其形成与成灾过程对于进一步认识震区泥石流发育特征具有重要的意义。根据现场调查,分析了太平驿沟泥石流流域特征,特别是地震条件下的泥石流物源特征,在此基础上讨论了泥石流起动过程和堆积过程。该实例表明了汶川震区泥石流已进入一个新的活跃期。因此,应该开展对汶川地震区的泥石流风险评估和监测、早期预警等研究,采取有效的工程措施控制泥石流的发生和危害。     

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.     

C4.5算法和GIS技术在波密县滑坡灾害风险评估中的应用

波密县地处西藏东南部,地貌地质环境特殊,滑坡灾害频发。本文选取地层岩性、边坡高度、边坡角度、坡面走向、水系距离和植被覆盖度作为评价因子,通过ArcGIS提取滑坡灾害评价因子相关数据,并利用C4.5算法建立的决策树分类模型对研究区域滑坡灾害的风险性进行了定量评估。结果表明:该模型总体预测精度达到89.7%,有效预测精度高达96.2%。表明该模型具有较高的精度和置信度,为波密县滑坡灾害的预测性分析提供参考。     

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.     

A method for quick assessment of earthquake-triggered landslide hazards: a case study of the Mw6.1 2014 Ludian,China earthquake

Rapid assessment of the distribution of earthquake-triggered landslides is an important component of effective disaster mitigation. The effort should be based on both seismic landslide susceptibility and the ground shaking intensity, which is usually measured by peak ground acceleration (PGA). In this paper, we address this issue by analyzing data from the Mw6.1 2014 Ludian, China earthquake. The Newmark method of rigid-block modeling was applied to calculate the critical acceleration of slopes in the study area, which serve as measurement of slope stability under seismic load. The assessment of earthquake-triggered landslide hazard was conducted by comparing these critical accelerations with the distribution of known PGA values. The study area was classified into zones of five levels of landslide hazard: high, moderate high, moderate, light, and very light. Comparison shows that the resulting landslide hazard zones agree with the actual distribution of earthquake-triggered landslides. Nearly 70% of landslides are located in areas of high and moderately high hazard, which occupy only 17% of the study region. This paper demonstrates that using PGA, combined with the analysis of seismic landslide susceptibility, allows a reliable assessment of earthquake-triggered landslides hazards. This easy-operation mapping method is expected to be helpful in emergency preparedness planning, as well as in seismic landslide hazard zoning.

     

蒋家沟流域暴雨滑坡泥石流共生关系试验研究

分析了蒋家沟流域内特殊环境下崩中有滑、滑中带崩的特殊形式的滑坡。通过大型人工降雨滑坡泥石流试验和小型模型试验，对试验现象进行观测和含水量监测，研究暴雨条件下发生的坡面侵蚀、崩滑现象和由此引发滑坡，滑坡土体转化成泥石流的全过程，揭示了蒋家沟流域特殊环境下的暴雨、滑坡、泥石流共生关系。试验证实，蒋家沟流域暴雨、滑坡、泥石流共生关系中含水量分布有一定范围。     

基于ArcGIS的四川松新黑水河地区滑坡危险性评价

以松新黑水河地区作为研究区域,基于遥感解译、野外调查统计、地质环境分析、典型滑坡研究的基础上,选取坡度、工程地质岩组、斜坡结构、断裂构造、降雨、人类工程活动等6个与滑坡发生相关的要素作为危险性评价因子。在ArcGIS空间分析模块中,采用自然断点法的数据分类方法,运用频率比——面域模型,对研究区滑坡危险性进行了评价与区划。研究结果表明:松新黑水河地区滑坡危险性分区为:高危险区、中等危险区、低危险区3个区域,所占研究区面积比例分别为32%、50%、18%。     

滑坡的易滑度分区及其概率预报模式

滑坡的发生主要由地形、地质和降雨三方面因素决定。基于区域地质-气象耦合分析的思路,有可能提高区域性滑坡的预报精度。首先通过将降雨条件和地质环境条件相结合的方法,提出一种新的滑坡概率预报模式,利用数理统计分析,提出利用最大24h雨强和前15d实效降雨量作为滑坡灾害发生的短期预报判据;然后以重庆市区作为研究对象,选择岩性组合、地形坡度、边坡形态、岩体结构和水文地质五大因素及其21种状态为预测变量,利用信息量法进行了易滑度的分区;最后,对概率预报滑坡的可行性进行了实例分析和探讨。     

基于WEBGIS和四库一体技术的三峡库区滑坡灾害预测预报系统研究

 在三峡库区开展的地质灾害稳定性评价、危险性区划、风险分析以及滑坡灾害预测预报所获成果的基础上,利用三期灾害地质图编绘、专业监测中崩塌滑坡预报模型和预报判据等资料,根据气象、库水位变化、人类工程活动、滑坡监测等信息,开发基于WEBGIS和四库一体技术的滑坡灾害预测预报系统。该系统主要包括区域滑坡灾害危险性评价、单体滑坡灾害时间预报、滑坡涌浪计算、灾情评估以及信息实时发布等功能模块,集成20多种适应于库区地质环境规律和滑坡灾害发育特点的模型;四库一体模式(模型库、方法库、数据仓库、知识库)即以模型为主导,调用方法,提取数据,模型求解,最后将专家决策结果作为知识源存入知识库。该系统在示范区巴东新城区和典型滑坡八字门和白水河滑坡上进行试运行,取得较好的应用成果,该系统的设计与实现为库区地质灾害预警决策和应急指挥提供技术支持,为库区人民生命和财产安全提供强有力的保障。     

北京市延庆区石窑村南地沟泥石流特征及发展趋势预测

本文以北京市延庆区石窑村南地沟泥石流为研究对象,通过野外调查与GIS统计分析,研究该流域降雨条件、地形地貌和沟道条件、物源条件等形成条件特征,针对流域内松散堆积物转换,开展了流域分区特征分析;通过14个因子分析,建立了该泥石流的发育阶段识别模型,对其发展趋势进行了预测;利用单沟泥石流堆积区公式开展了最大危险区预测研究,提出相应的防治措施建议。研究表明:石窑村南地沟泥石流内松散堆积物动储量达18.36×10~4 m~3,物源类型划分为冲洪积物源、残坡积物源、人工堆积物源和崩滑塌物源4种,其中残坡积所占比重最大。该泥石流属于暴雨-沟谷型-支沟群发型、中易发泥石流,泥石流发展阶段处于发育期,最大危险区面积为0.413 km~2,对沟口堆积区的石窑村及村民的生命财产安全造成威胁,建议采用局部物源平整与疏理排导渠相结合的综合治理措施。本文为该区地质灾害防治提供基础依据。     

Assessment and validation of GIS-based landslide susceptibility maps: a case study from Feltrino stream basin (Central Italy)

Landslide susceptibility studies focus on producing susceptibility maps starting from landslide inventories and considering the main conditioning factors. The validity of susceptibility maps must be verified in terms of model accuracy and prediction skills. This paper deals with a GIS-based landslide susceptibility analysis and relative validation in a hilly-coastal test-area in Adriatic Central Italy. The susceptibility analysis was performed via bivariate statistics using the Landslide-Index method and a detailed (field-based) landslide inventory. Selection and mapping of conditioning factors and landslide inventories was derived from detail geomorphological analyses of the study area. The susceptibility map was validated using recent (shallow) landslides in terms of both model accuracy and prediction skills, via Success rate and Prediction rate curves, respectively. In addition, a pre-existing official landslide inventory was applied to the model to test whether it can be used when a detailed (field-based) inventory is not available, thereby extending its usability in similar physiographic regions. The outcome of this study reveals that slope and lithology are the main conditioning factor of landslides, but also highlights the key role of surficial deposits in susceptibility assessment, for both their type and thickness. The validation results show the effectiveness of the susceptibility model in both model accuracy and prediction skills given the good percentage of correctly classified landslides. Moreover, comparison of the susceptibility map with the official Regional landslides inventory proves the possibility of using the developed susceptibility model also in the absence of detailed landslide mapping, by considering inventories that are already available.