强降雨作用下边(滑)坡稳定性分析及预警技术研究

以四川汉源二蛮山滑坡为例,根据现场滑坡情况勘查及室内试验确定土体参数;选择内置VBA为开发工具,开发基于ArcGIS的边（滑）坡稳定性分析插件,并据此得出研究区域危险区划评价图.研究结果表明,特殊地形条件、震后地质构造、连续强降雨以及坡体非饱和渗流等,使孔隙水压力增加和土基质吸力迅速减少,导致坡体滑移面处土的抗剪强度降低而发生滑坡;基于ArcGIS软件得出研究区域危险区划评价图,与滑坡的实际情况具有较高吻合度.研究成果为深入分析强降雨对边（滑）坡影响及边（滑）坡预警提供了新的途径.     

GIS-based landslide susceptibility evaluation using fuzzy-AHP multi-criteria decision-making techniques in the Abha Watershed,Saudi Arabia

Landslides are natural geological disasters causing massive destructions and loss of lives, as well as severe damage to natural resources, so it is essential to delineate the area that probably will be affected by landslides. Landslide susceptibility mapping (LSM) is making increasing implications for GIS-based spatial analysis in combination with multi-criteria evaluation (MCE) methods. It is considered to be an effective tool to understand natural disasters related to mass movements and carry out an appropriate risk assessment. This study is based on an integrated approach of GIS and statistical modelling including fuzzy analytical hierarchy process (FAHP), weighted linear combination and MCE models. In the modelling process, eleven causative factors include slope aspect, slope, rainfall, geology, geomorphology, distance from lineament, distance from drainage networks, distance from the road, land use/land cover, soil erodibility and vegetation proportion were identified for landslide susceptibility mapping. These factors were identified based on the (1) literature review, (2) the expert knowledge, (3) field observation, (4) geophysical investigation, and (5) multivariate techniques. Initially, analytical hierarchy process linked with the fuzzy set theory is used in pairwise comparisons of LSM criteria for ranking purposes. Thereafter, fuzzy membership functions were carried out to determine the criteria weights used in the development of a landslide susceptibility map. These selected thematic maps were integrated using a weighted linear combination method to create the final landslide susceptibility map. Finally, a validation of the results was carried out using a sensitivity analysis based on receiver operator curves and an overlay method using the landslide inventory map. The study results show that the weighted overlay analysis method using the FAHP and eigenvector method is a reliable technique to map landslide susceptibility areas. The landslide susceptibility areas were classified into five categories, viz. very low susceptibility, low susceptibility, moderate susceptibility, high susceptibility, and very high susceptibility. The very high and high susceptibility zones account for 15.11% area coverage. The results are useful to get an impression of the sustainability of the watershed in terms of landsliding and therefore may help decision makers in future planning and mitigation of landslide impacts.     

广州市地质风险区划及规划建设应对指引

基于广州市区域地质条件等特点和在风险区划理论知识支撑下,构建了广州市规划建设地质风险区划评价指标体系,其中一级指标为采空区、岩溶发育程度、地形地貌、岩土体工程地质条件、气象水文和人类工程活动7个因子和11个二级因子。通过GIS软件,绘制了广州市规划建设地质风险分区图,共划分城市建设用地优良区、中厚松软土区、厚层松软土区、山地区、岩溶弱发育区、岩溶强发育区、采空区7个区,其中进行高强度开发和中等-高强度开发的地区有优良区、中厚松软土区、厚层松软土区、岩溶弱发育区,占广州市面积的46.7%,适度开发为岩溶强发育区和采空区,占广州市面积的3.7%,限制开发主要是山地区,占广州市面积49.6%,同时给出了不同区在城市建设过程中面临的地质风险。对地质条件类似的其他城市可供借鉴和参考。     

Risk assessment of land subsidence at Tianjin coastal area in China

Risk assessment and zoning are very important to risk management. In this study, a land subsidence risk assessment index was proposed based on the Disaster Risk Index. The cumulative subsidence volume, the land subsidence velocity, and the groundwater exploitation intensity were collected, analyzed, and put together to create a land subsidence hazard evaluation map in Tianjin coastal area. The population density, Gross Domestic Product per square kilometer, and construction land proportion were adopted as indexes to create the vulnerability map. In addition, the capability of land subsidence prevention and reduction was also assessed. Finally, the land subsidence risk map was created by combing the hazard, vulnerability, and the capability of land subsidence prevention and reduction map. Specifically, the land subsidence risk was classified into five levels, i.e., very high, high, medium, low, and very low. The result of this research could provide a solid basis for the sustainable development as well as disaster prevention policy-making of Tianjin city.     

基于投影寻踪模型的滑坡危险性等级评价

危险性评价是滑坡灾害预防与减灾工作首要解决的重要内容.在地理信息系统技术支持下, 以山地灾害频发区——小江流域作为研究对象, 选取坡度、土体粘聚力和内摩擦角这3个评价指标构建滑坡危险性分级评价指标体系, 将投影寻踪技术运用到滑坡危险性等级评价中, 对评价样本的各指标因素进行线性投影, 以最优投影方向所对应的投影特征值作为评价依据, 建立了滑坡危险性等级综合评价模型, 绘制了滑坡危险性等级分布图.结果表明: 研究区极高危险区、高危险区、中等危险区、低危险区和极低危险区的面积比例为14.28∶9.41∶69.12∶7.00∶0.19;根据所建立的5级评价指标体系对研究区60个土质滑坡点资料进行了验证, 在占研究区总面积23.69%的高、极高危险区的小范围内, 实际发生土质滑坡数量45个, 占总土质滑坡数量的75.00%;中等危险性级别以上区域拥有的土质滑坡数量占全部土质滑坡的96.67%;不同危险性级别的滑坡体积方量统计结果表明, 滑坡体积方量密度随危险性级别的提高而迅速增加.对比评价结果及实测结果可知, 投影寻踪分级结果符合实际情况, 证实了该方法的正确性, 为滑坡危险性评价提供了一条新思路.      

Rockfall susceptibility zoning at a large scale: From geomorphological inventory to preliminary land use planning

Rockfall, up to several hundreds of cubic meters, is a frequent and rapid landslide which menaces extensive areas in mountainous territories. Rockfall susceptibility zoning map at a large scale (1:5000–1:25 000) can be the first tool for land use planning in order to manage rockfall risk. A methodology allowing to analyze susceptibility in extensive areas with optimum cost/benefit relationship is needed. This work analyzes rockfall susceptibility in an extensive rocky mountain of the Principality of Andorra (Pyrenees Mountains), first on the rock slope and then on the exposed area located below. The rockfall record, obtained by means of geomorphological analysis, supplies the main data to analyze the susceptibility on the rock slope. An additional historical inventory verifies the accuracy of rockfall sizes recorded by means of the geomorphological analysis. According to the classification recommended by the Guidelines of Joint Technical Committee, the density of rockfall features on the rock slope assesses susceptibility in four levels. Subsequently, susceptibility on exposed areas has been analyzed by means of reach probability of rock blocks analysis using empirical models. Data acquired from thirteen recent events, from 1999 to 2004, have been used to verify the accuracy of the two empirical models mainly used (reach angle and shadow angle). Five reach probability limits (1, 0.5, 0.25, 0.01, and 0) establish boundaries between susceptibility levels. The resulting rockfall susceptibility zoning map allows: (a) to identify land areas and human elements exposed to rockfalls and, (b) to establish several exposition levels. This map can be a useful and cost-effective tool for administrations responsible to manage natural risk in order to guide urban grow in extensive areas or decide upon work programs based on in-depth analysis (hazard and risk).     

Landslide susceptibility assessment using the bivariate statistical analysis and the index of entropy in the Sibiciu Basin (Romania)

The Sibiciu Basin is located in Romania between the Buzău Mountains and the Buzau Subcarpathians (Curvature Carpathians and Subcarpathians). The geology of the basin consists of Paleogene flysch deposits represented by an alternation of sandstones, marls, clays and schists and Neogene deposits represented by marls, clays and sands. The area is affected by different types of landslides (shallow, medium-deep and deep-seated failures). In Romania, in the last decades, direct and indirect methods have been applied for landslide susceptibility assessment. The most utilized before 2000 were based on qualitative approaches. This study evaluates the landslide susceptibility in the Sibiciu Basin using a bivariate statistical analysis and an index of entropy. A landslide inventory map was prepared, and a susceptibility estimate was assessed based on the following parameters which influence the landslide occurrence: slope angle, slope aspect, curvature, lithology and land use. The landslide susceptibility map was divided into five classes showing very low to very high landslide susceptibility areas.     

Rockfall susceptibility zoning based on back analysis of rockfall deposit inventory in Gunung Kelir,Java

A rockfall susceptibility based on trajectory-energy/velocity approach needs release area or rockfall source. However, identification of rockfall source is not always possible for some areas in Indonesia. This paper presents a rockfall susceptibility zoning based on back analysis technique of rockfall deposit inventory in Gunung Kelir, Java. There were several steps in the rockfall susceptibility zoning: (1) rockfall deposit inventory, (2) rockfall simulation based on back analysis of rockfall deposit inventory, (3) sensitivity analysis, and (4) rockfall susceptibility zoning. The result suggests that the travel distance is affected by the spatial distribution of rockfall source, lithology or surface material, and topography (angle of slope and angle of aspect). Final trajectories were employed to generate landslide susceptibility map which may allow a policy maker to have an advanced consideration to achieve specified risk measures and evaluation of their cost efficiency to optimize budget and design. Application of rockfall susceptibility zoning based on back analysis of rockfall deposits is efficient where rockfall source information is unavailable.     

Modelling wind-erosion risk in the Laghouat region (Algeria) using geomatics approach

Wind-erosion risk is a challenge that threatens land development in dry-land regions. Soil analysis, remote sensing, climatic, vegetal cover and topographic data were used in a geographic information system (GIS), using multi-criteria analysis (MCA) to map wind-erosion risk (R_we) in Laghouat, Algeria. The approach was based on modelling the risk and incorporating topographic and climatic effects. The maps were coded according to their sensitivity to wind erosion and to their socio-economic potential, from low to very high. By overlapping the effects of these layers, qualitative maps were drawn to reflect the potential sensitivity to wind erosion per unit area. The results indicated that severe wind erosion affects mainly all the southern parts and some parts in the north of Laghouat, where wind-erosion hazard (H_we) is very high in 43% of the total area, and which was affected mainly by natural parameters such as soil, topography and wind. The results also identified features vulnerable to R_we. The product of the hazard and the stake maps indicated the potential risk areas that need preventive measures; this was more than half of the study area, making it essential to undertake environmental management and land-use planning.     

Identification and prioritization of sub-watersheds for land and water management using InVEST SDR model: Rmelriver basin,Tunisia

Tunisia presents many favorable conditions for the outbreak of water erosion because of its climatic and physical characteristics. This phenomenon represents a serious threat to the natural resources of soil and water. The aim of the present study is to identify the most vulnerable areas in order to help managers implement an effective management program. Thematic layers and parameters were integrated in the InVEST (Integrated Valuation of Environmental Services and Trade-offs) SDR (Sediment Delivery Ratio). Soil loss and sediment yield were calculated by the model and compared to observed data. The Rmel river basin was divided into 17 sub-watersheds using the dam axis as the main outlet. Results reveal that approximately 60% of the basin presents soil loss more than 5 ton/ha/year. Soil erosion map demonstrates that soil erosion risk increases with increased slope gradient, especially in agricultural lands. Sub-catchment prioritizations have been fixed based on soil erosion risk. Results show that sub-catchment 16 presents the highest soil loss with a value of 65 ton/ha/year. Sub-catchment presenting high soil erosion risk needs to give a high priority in conservation planning.     

南京市地基稳定性区划图

为了城市土地的合理使用，保证建筑物的安全，目前在城市岩土工程问题中对土地的合理利用研究和评价方法不断涌现。本文根据南京市的基岩岩性、地貌特征、覆盖层厚度和第四纪松散沉积物分布情况，划分为五个基本类型，各个分区具有不同的工程地质特征。     

Fuzzy-based method for landslide hazard assessment in active seismic zone of Himalaya

Landslides in Himalaya cause widespread damage in terms of property and human lives. It the present study, an attempt is made to derive information on causative parameters and preparation of landslide-susceptible map using fuzzy data integration in one of the seismically active region of Garhwal Himalaya that was recently devastated by a huge landslide. High-resolution remotely sensed data products acquired from Indian Remote Sensing Satellite before and after the landslide event were processed to improve interpretability and derivation of causative parameters. Spatial data sets such as lithology, rock weathering, geomorphology, lineaments, drainage, land use, anthropogenic factor, soil type and depth, slope gradient, and slope aspect were integrated using fuzzy gamma operator. The final map was reclassified in to five classes such as highly to lowly susceptible classes based on cumulative cutoff. The result shows around 72% of known landslide areas including the large Uttarkashi landslide in the high and very high susceptibility classes comprising of only 37% of the total area. The precipitation data from ground- and satellite-based observations were compared; the precipitation threshold and the role of seismic activity were analyzed for initiation of landslide.     

考虑基质吸力作用的Newmark改进模型在地震滑坡风险评价中的应用

传统的Newmark模型常对地下水位以上由负孔隙水压力提供的部分抗剪强度忽略不计,这对于滑动面的主要部分处在地下水位以下时较为合理,但对地下水位很深或考虑出现浅层滑动的坡体,其计算结果过于保守。因此,文章将Newmark累积位移模型扩展至非饱和土力学领域,在考虑基质吸力作用的基础上,改进了Newmark模型计算公式。分别利用Newmark传统模型和改进模型对甘肃礼县幅区域内的地震滑坡进行易发性分区,并在此基础上分别开展50年超越概率10%情况下的地震滑坡危险性分区和风险评价,最后利用ROC曲线对评价结果进行验证和比较。结果表明:改进模型所得易发区和危险区的计算结果明显优于传统模型计算结果;改进的模型所得风险区的计算结果虽然改进效果不明显,但仍优于传统模型计算结果。由于考虑基质吸力作用的Newmark改进模型充分发挥了基质吸力的贡献,使得计算结果更为合理,研究成果可为相关地区开展地震滑坡易发性分区、危险性分析和风险评价提供新的参考。     

Estimation of spatial patterns of soil erosion using remote sensing and GIS: a case study of Indravati catchment

Soil erosion is a serious environmental problem in Indravati catchment. It carries the highest amount of sediments compared with other catchments in India. This catchment spreading an area of 41,285 km² is drained by river Indravati, which is one of the northern tributaries of the river Godavari in its lower reach. In the present study, USLE is used to estimate potential soil erosion from river Indravati catchment. Both magnitude and spatial distribution of potential soil erosion in the catchment is determined. The derived soil loss map from USLE model is classified into six categories ranging from slight to very severe risk depending on the calculated soil erosion amount. The soil erosion map is linked to elevation and slope maps to identify the area for conservation practice in order to reduce the soil loss. From the model output predictions, it is found that average erosion rate predicted is 18.00 tons/ha/year and sediment yield at the out let of the catchment is 22.30 Million tons per annum. The predicted sediment yield verified with the observed data.     

An integrated GIS-based approach for geohazards risk assessment in coal mines

From the viewpoint of safety in underground coal mining, the most suitable mining panel is the one with minimum geological structures, the right machinery, and equipment selection, trained employee, and proficient stope management. Since the ground parameters are uncontrollable and inherent uncertainties exist, a high percent of risk will usually accompany the underground coal mining activities. The main purpose of this study is to present a geological–geotechnical risk assessment model for identification of high risk-prone areas in underground coal mines using an integrated GIS-geostatistics system. Tabas as the first mechanized and largest underground coal mine in Iran was selected as a case study in this study. Gas content of coal seam, Coal Mine Roof Rating (CMRR), initial in situ stress state, fault throw, and orientation were selected as hazard/risk factors. For estimating the amount of coal seam gas content, CMRR and initial in situ stress in unsampled areas and providing the prediction maps, geostatistics module in ArcGIS was used. Rock engineering system–interaction matrix method was used for attribute weight assignment. Next, the attribute layers were weighted, rated, and overlaid to create a final map of geohazards risk. The analysis results of final risk map indicate that about 45% of under study area is prone to high to very high geohazards risk. Comparison of the results with experiences obtained during the early part of the mine and mined-out panels showed generally good agreement with promising ideas. This highlights the potential application of the GIS-based approach for hazards detection and geohazards risk assessment in underground coal mines.     

基于斜坡单元的滑坡风险识别

识别斜坡地质灾害风险已成为西南山区地质灾害防治的重要基础工作,通过GIS软件划分出孕灾斜坡单元,选取坡度、坡高、覆盖层厚度、滑体土类型、人类工程活动、日最大降雨量等6项指标作为评价因子,利用层次分析法开展山区大比例尺地质灾害危险性评价,初步评价出研究区危险性斜坡。以万山区1:1万地质灾害风险调查获取的斜坡剖面模型为基础,通过取样、试验,综合选取岩土体物理力学参数,利用有限元软件对暴雨状态下的高危险斜坡进行数值模拟,通过强度折减计算出安全系数均小于1.05,并存在不同程度的塑性贯通区。其分析结果与层次分析法评价结果一致,可作为西南山区浅层土质滑坡隐患识别的定量化评价方法。     

Regional-scale landslide activity and landslide susceptibility zonation in the Nepal Himalaya

Landslide susceptibility zonation mapping is a fundamental procedure for geo-disaster management in tropical and sub-tropical regions. Recently, various landslide susceptibility zonation models have been introduced in Nepal with diverse approaches of assessment. However, validation is still a problem. Additionally, the role of various predisposing causative parameters for landslide activity is still not well understood in the Nepal Himalaya. To address these issues of susceptibility zonation and landslide activity, about 4,000 km² area of central Nepal was selected for regional-scale assessment of landslide activity and susceptibility zonation mapping. In total, 655 new landslides and 9,229 old landslides were identified with the study area with the help of satellite images, aerial photographs, field data and available reports. The old landslide inventory was “blind landslide database” and could not explain the particular rainfall event responsible for the particular landslide. But considering size of the landslide, blind landslide inventory was reclassified into two databases: short-duration high-intensity rainfall-induced landslide inventory and long-duration low-intensity rainfall-induced landslide inventory. These landslide inventory maps were considered as proxy maps of multiple rainfall event-based landslide inventories. Similarly, all 9,884 landslides were considered for the activity assessment of predisposing causative parameters. For the Nepal Himalaya, slope, slope aspect, geology and road construction activity (anthropogenic cause) were identified as most affective predisposing causative parameters for landslide activity. For susceptibility zonation, multivariate approach was considered and two proxy rainfall event-based landslide databases were used for the logistic regression modelling, while a relatively recent landslide database was used in validation. Two event-based susceptibility zonation maps were merged and rectified to prepare the final susceptibility zonation map and its prediction rate was found to be more than 82 %. From this work, it is concluded that rectification of susceptibility zonation map is very appropriate and reliable. The results of this research contribute to a significant improvement in landslide inventory preparation procedure, susceptibility zonation mapping approaches as well as role of various predisposing causative parameters for the landslide activity.     

基于典型剖面分析的区域斜坡稳定性分区方法

为了研究大范围内区域斜坡的稳定性,本文提出了一套基于典型剖面分析的区域斜坡稳定性分区方法。首先,在ArcGIS水文分析的基础上划分斜坡单元;其次,利用MATLAB开发程序,完成斜坡单元的剖分、典型剖面的搜索和提取工作;再次,利用MATLAB动态生成FLAC2D命令流文件,自动计算得到区域斜坡稳定性系数的分布;最后,基于定量计算在ArcGIS中对区域斜坡进行稳定性分区评价。本文选取陕西耀县幅1:5万环境地质调查区内黄土斜坡较发育段作为研究对象,对本方法进行验证。计算结果:（1）研究区域划分为不稳定区、基本稳定区和稳定区3个区;（2）整个方法体系采取智能化的设计理念,各计算步骤之间自动调用执行,程序衔接良好;（3）将GIS分析与外部计算相结合,实现单个斜坡的稳定性计算到区域的推广。     

Assessment of the flash flood potential of Bâsca River Catchment (Romania) based on physiographic factors

The purpose of this paper is to identify areas with high flash-flood potential based on an evaluation of physiographic factors controlling the formation of surface runoff. The research method relies on the use of the Flash Flood Potential Index (FFPI), which incorporates physiographic characteristics from the catchment (terrain slope, profile curvature, land use and soil texture). The spatial distribution of the physiographic factors (which contribute to the creation, control and concentration within the drainage network of the overland flow) and the classified zoning of areas according to their hydrological response were achieved with GIS techniques. The results obtained show that physiographic factors on 227 sq km (29%) favor surface runoff on slopes and its localization towards the drainage network. Notably, the highest values of FFPI belong to the lower part of the catchment, where high human population density can be found, reflecting an increased vulnerability to floods and inundations of this area.     

山区公路高切坡岩土安全分区研究

将统一强度理论和Lode应力参数进行耦合,建立计算山区公路高切坡局部安全稳定的数学模型。基于ArcGIS9.3对高切坡数据进行前期处理和分析,采用有限元分析软件对高切坡研究断面进行数值模拟,得到断面各节点的相关参数,利用ArcGIS9.3对数值模拟结果进行后期分析与可视化,最终得到研究断面岩土安全分区图。以重庆市两巫（巫山－巫溪）路高切坡K88＋680为实例,模拟得到K88＋660、K88＋680和K88＋700三个断面的安全分区图,并在此基础上通过空间插值方法得出该路段坡面的安全分区图。研究结果与实际相吻合,可用于指导该高切坡的开挖及防治,同时研究方法对于高切坡的局部安全研究具有重要的参考价值。