共查询到19条相似文献，搜索用时 187 毫秒
1.
边坡稳定性影响因素众多,其中一部分具有明显的不确定性,用经典数学理论及力学模型很难描述。采用二级模糊综合评判法,对影响边坡稳定的离散型和连续型因素采用不同方法确定隶属度,并利用二元对比分析法给出各因素权重值;同时考虑降雨对边坡稳定的重要影响,对降雨后各影响因素的权重进行修正,建立边坡稳定的二级模糊综合评判计算模型,评价降雨前后边坡稳定性的变化。研究结果表明：模型所采用的隶属函数,充分考虑了各个因素的不同特点和分布规律;考虑降雨前后权重的变化,能使评判结果更趋合理。以实际工程为例,模糊综合评判结果显示：降雨前边坡处于基本稳定状态,降雨后处于欠稳定状态,与经典极限平衡法计算结果一致。 相似文献
2.
3.
基于模糊综合优化模型的地下水质量评价 总被引：1，自引：0，他引：1
在应用模糊综合评判法进行地下水水质评估中,存在地下水质量标准与方法要求的分级标准不匹配以及隶属度绝对化的问题。文中在模糊综合评判法的基础上,引入相对隶属度概念表征评价指标与水质标准间的模糊关系,从而建立起模糊综合优化模型。应用该模型对青岛市大沽河地下水源地水质状况进行评价和分析对比,研究结果表明,地下水质量标准符合优化模型对评判标准类型的要求,克服了传统模型存在的标准不兼容问题。指标实测值介于某中间等级时,该等级与左右相邻等级的相对隶属度值均大于0。与绝对的隶属度分布相比,优化模型拓展了指标在各等级隶属度的分布,真实反映了其相对的特征。水源地南部地区(监测井S1和S3)地下水的总硬度、溶解性总固体与其他特征污染物的含量均超过Ⅳ类水质标准,优化模型判定的水质等级也为Ⅳ类水,评价结果符合研究区的实际情况,表明优化模型是可靠的。 相似文献
4.
随机-模糊统计方法在岩土特征参数指标统计中的应用 总被引：1，自引：0，他引：1
岩土工程中的随机-模糊统计方法用模糊理论准确表达了岩土材料的空间变异性。针对随机-模糊方法权重系数的取值进行了讨论,研究了“参照点”在随机-模糊方法的意义,指出了“参照点”与核点无限接近时的最大隶属度才是所要求的正确结果,并根据模糊随机原理提出了直接迭代求解目标函数的流程。采用建议方法对某核电岩土工程中的参数进行了计算,获得了取不同“参照点”时各样本的隶属度曲线以及“参照点”向核点逐步逼近的过程曲线。结果表明,隶属度函数采用指数函数是合理的,样本隶属度分布形态为窄域“正态”分布。所得结论可为随机-模糊统计方法在岩土工程中的应用提供基本理论依据。 相似文献
5.
将T-S模糊系统理论和人工神经网络相结合,利用模糊理论隶属度对模糊性有很强的识别精度,将泥石流危险性指标隶属度作为神经网络的激活函数输入,使用正态分布方法产生训练数据,再利用BP神经网络的误差反向传播对TS模糊系统隶属度函数等的参数进行训练调整,从而建立泥石流危险性评价的模糊神经网络模型。利用建立好的模型对云南东川八条典型泥石流沟的危险性进行评价,获得客观合理的评价结果。与刘希林的灰色聚类法和可拓物元方法的纵向对比和与线性内插产生训练数据方法横向对比表明:使用该方法能较真实地反映实际泥石流沟的危险性等级,证明模糊神经网络理论应用于泥石流危险性评价的有效性和可行性。 相似文献
6.
模糊逻辑法在云南中甸地区铜矿潜力预测中的应用 总被引：2，自引：0，他引：2
模糊逻辑建模应用于矿产预测时分为两步:①变量模糊化,应用隶属函数计算变量的模糊隶属度;②模糊综合,应用模糊算子(模糊与、模糊或、模糊代数和、模糊代数积和伽马算子)对模糊化后的变量进行综合,生成最终的模糊有利度图.在介绍了模糊逻辑的基本原理和详细分析云南中甸铜成矿规律的基础上,应用ArcView GIS及其扩展模块ArcSDM对研究区地质、地球化学、线性构造等方面的数据进行了处理,提取了预测变量.模型应用于云南中甸普朗地区斑岩铜矿的区域成矿预测(1:20万)结果显示,预测出的成矿潜力区包含了81%以上的已知矿点,可以用于指导进一步的大比例勘查工作. 相似文献
7.
北京市门头沟区某公路岩质边坡数量多,边坡物理力学性质及其影响因素复杂多变,无法获取每个边坡岩体的物理力学参数,因此,对大量边坡进行力学稳定性分析十分困难。采用层次分析和模糊综合评价方法,根据各种因素对岩质边坡稳定性影响的定性分析,确定了2级4类共9个边坡稳定性影响因子,将边坡的稳定性级别划分为4级,即稳定、基本稳定、较不稳定和不稳定; 然后,构建了隶属度矩阵和权重矩阵; 最后,对每个边坡的稳定性进行模糊综合评价。分析结果表明,在所研究的113个边坡中,不稳定边坡3个,占总边坡的3%,较不稳定边坡27个,占24%,基本稳定边坡52个,占46%,稳定边坡31个,占27%。因此认为: 当边坡数量众多、边界条件模糊、影响因素复杂时,模糊综合评判是比较合适的边坡稳定性分析方法; 应用最大隶属度原则时,需根据各种因素对边坡稳定性影响的因果关系,对最大隶属度原则的有效性进行评估,以防出现评判失效。 相似文献
8.
9.
为了克服勘探基地选择中的盲目性,本文提出了一种根据海明距离建立的模糊相似优先比矩阵的方法,该法可较科学地确定选择勘探基地的优先顺序.方法的大致步骤是:1)收集原始资料;2)选择关系密切的变量,计算海明距离;3)根据各地质变量的隶属度函数计算各变量的隶属度;4)计算模糊相似优先比矩阵;5 )分析上述矩阵,确定选择勘探基地的优先顺序. 相似文献
10.
11.
根据农田坡面氮、磷流失的主要过程,建立了基于次降雨事件的坡面氮、磷迁移模型。模型采用改进的Green-Ampt方程和运动波方程计算下渗与坡面流,土壤侵蚀采用修改的欧洲土壤侵蚀模型计算,用考虑了侵蚀影响与扩散作用的迁移模型计算坡面氮、磷迁移过程,采用一维对流扩散方程计算氮、磷在土壤中的迁移过程。利用室内人工降雨资料对模型进行了率定及验证。结果表明,模型可以较好地模拟地表径流中氮、磷浓度,率定期与验证期模型效率系数均在0.89以上。根据坡地氮、磷流失机理,分析了降雨强度与地表坡度对坡面径流中氮、磷浓度的影响。 相似文献
12.
Catchment-scale soil erosion and sediment yield simulation using a spatially distributed erosion model 总被引：1，自引：1，他引：0
Increasing rainfall intensity and frequency due to extreme climate change and haphazard land development are aggravating soil erosion problems in Korea. A quantitative estimate of the amount of sediment from the catchment is essential for soil and water conservation planning and management. Essential to catchment-scale soil erosion modeling is the ability to represent the fluvial transport system associated with the processes of detachment, transport, and deposition of soil particles due to rainfall and surface flow. This study applied a spatially distributed hydrologic model of rainfall–runoff–sediment yield simulation for flood events due to typhoons and then assessed the impact of topographic and climatic factors on erosion and deposition at a catchment scale. Measured versus predicted values of runoff and sediment discharge were acceptable in terms of applied model performance measures despite underestimation of simulated sediment loads near peak concentrations. Erosion occurred widely throughout the catchment, whereas deposition appeared near the channel network grid cells with a short hillslope flow path distance and gentle slope; the critical values of both topographic factors, providing only deposition, were observed at 3.5 (km) (hillslope flow path distance) and 0.2 (m/m) (local slope), respectively. In addition, spatially heterogeneous rainfall intensity, dependent on Thiessen polygons, led to spatially distinct net-erosion patterns; erosion increased gradually as rainfall amount increased, whereas deposition responded irregularly to variations in rainfall. 相似文献
13.
Application and verification of fuzzy algebraic operators to landslide susceptibility mapping 总被引：4，自引：2，他引：4
Saro Lee 《Environmental Geology》2007,52(4):615-623
The aim of this study was to apply and to verify the use of fuzzy logic to landslide susceptibility mapping in the Gangneung
area, Korea, using a geographic information system (GIS). For this aim, in the study, a data-derived model (frequency ratio)
and a knowledge-derived model (fuzzy operator) were combined. Landslide locations were identified by changing the detection
technique of KOMPSAT-1 images and checked by field studies. For landslide susceptibility mapping, maps of the topography,
lineaments, soil, forest, and land cover were extracted from the spatial data sets, and the eight factors influencing landslide
occurrence were obtained from the database. Using the factors and the identified landslide, the fuzzy membership values were
calculated. Then fuzzy algebraic operators were applied to the fuzzy membership values for landslide susceptibility mapping.
Finally, the produced map was verified by comparing with existing landslide locations for calculating prediction accuracy.
Among the fuzzy operators, in the case in which the gamma operator (λ = 0.975) showed the best accuracy (84.68%) while the
case in which the fuzzy or operator was applied showed the worst accuracy (66.50%). 相似文献
14.
Probabilistic Fuzzy Logic Modeling: Quantifying Uncertainty of Mineral Prospectivity Models Using Monte Carlo Simulations 总被引：2，自引：0，他引：2
Significant uncertainties are associated with the definition of both the exploration targeting criteria and computational algorithms used to generate mineral prospectivity maps. In prospectivity modeling, the input and computational uncertainties are generally made implicit, by making a series of best-guess or best-fit decisions, on the basis of incomplete and imprecise information. The individual uncertainties are then compounded and propagated into the final prospectivity map as an implicit combined uncertainty which is impossible to directly analyze and use for decision making. This paper proposes a new approach to explicitly define uncertainties of individual targeting criteria and propagate them through a computational algorithm to evaluate the combined uncertainty of a prospectivity map. Applied to fuzzy logic prospectivity models, this approach involves replacing point estimates of fuzzy membership values by statistical distributions deemed representative of likely variability of the corresponding fuzzy membership values. Uncertainty is then propagated through a fuzzy logic inference system by applying Monte Carlo simulations. A final prospectivity map is represented by a grid of statistical distributions of fuzzy prospectivity. Such modeling of uncertainty in prospectivity analyses allows better definition of exploration target quality, as understanding of uncertainty is consistently captured, propagated and visualized in a transparent manner. The explicit uncertainty information of prospectivity maps can support further risk analysis and decision making. The proposed probabilistic fuzzy logic approach can be used in any area of geosciences to model uncertainty of complex fuzzy systems. 相似文献
15.
利用中子活化示踪法研究坡面土壤的侵蚀过程,发现坡面的相对侵蚀量从坡脚到坡顶随坡长的变化符合Weibull分布,其形状参数主要受降雨量、降雨历时和径流深度的影响,尺度参数主要与平均雨强、I30相关.坡面在侵蚀的同时也发生沉积,一般来说短历时高强度的降雨沉积量较小,而长历时低强度的降雨沉积量较大,某一部位侵蚀产沙的沉积量与其距离之间有y=axb的关系.坡面径流直接影响着坡面的输移比,当径流深和径流系数较高时,输移比接近于1,否则输移比降低. 相似文献
16.
喀斯特裸坡土壤侵蚀模拟研究 总被引：4，自引：0，他引：4
文章通过人工模拟降雨试验,研究不同地下孔（裂）隙度、基岩裸露率和雨强对地表、地下产流、产沙的影响,其结果表明:（1）土壤侵蚀与地下孔（裂）隙度具有较高相关性,地表产流、产沙随地下孔（裂）隙度的增大而减小,而地下则相反;（2）坡面径流刚产生时,雨滴击溅和薄层水流冲刷,土壤细小颗粒堵塞其毛管空隙,渗漏率减小,而地表径流量增大,土壤团聚体被破坏、分散和迁移,降水与土壤渗漏率增大,地表径流量减小,雨滴击溅增强,如此循环,降水与土壤渗漏率呈波动性变化;总体而言,地表、地下悬移质均随降雨历时呈下降趋势,而地表推移质则相反,地表、地下产流量变幅较小,趋于平行;（3）地表产流、产沙量随基岩裸露率增大呈波动性变化,总体呈下降趋势;而地下产流、产沙量随基岩裸露率增大呈波动性变化,总体呈增大趋势;（4）在较小雨强30 mm/h时,地表只产生悬移质流失,没有产生推移质流失;地表、地下产流、产沙都是随雨强增大而增大;雨强由30 mm/h增大到150 mm/h,地表累积产流量为538.5 L,累积产沙量为2 393.81 g,地下累积产流量为207.8 L,累积产沙量为687.73 g,累积产沙量的递增速率比累积产流量的递增速率要大,地表产流、产沙的递增速率大于地下产流、产沙的递增速率;（5）各因子与土壤侵蚀间相关程度为:降雨历时>雨强>地下孔（裂）隙度>基岩裸露率。该实验有助于为喀斯特地区的水土流失研究、评价及制订石漠化治理措施提供理论依据。 相似文献
17.
An attempt has been made to analyze the spatial-temporal characteristics of soil erosion vulnerability and soil loss from the forested region in the north-eastern Borneo, Sarawak, Malaysia during the last three decades (1991–2015) using the revised universal soil loss equation (RUSLE) and geographical information systems (GIS). The components of RUSLE such as rainfall erosivity (R), soil erodibility (K), slope-length and steepness (LS), cover management (C) and conservation practice (P) factors were grouped into two categories by keeping one set as temporally changing and others as static. Among them the R and C factors are calculated for the years 1991, 2001 and 2015 whereas the K and LS factors are considered for the single time frame. Because of the forested nature of the study area, the P factor is kept constant for the whole analysis. The R factor and C factor is shown changes in values and its distribution over the years, which reflected in the final soil loss and erosion vulnerability map as a change in the rate of erosion and spatial domain. The analysis of three time slices has shown that the maximum value of the soil loss per unit area i.e. at erosion hotspots, is relatively similar throughout at around 1636 to 1744 t/ha/y. This is the result of maximum values of R factor and C factor i.e. high rainfall erosivity combined with lack of vegetation cover in those hotspots, which are generally steeply sloping terrain. The reclassification of annual soil loss map into erosion vulnerability zones indicated a major increase in the spatial spread of erosion vulnerability from the year 1991 to 2015 with a significant increase in the high and critical erosion areas from 2.3% (1991) to 31.5% (2015). In 1991, over 84% of the study area was under low erosion vulnerability class but by the year 2015 only 12% was under low erosion vulnerability class. Moreover, a dynamic nature in the erosion pattern was found from the year 1991 to 2015 with more linear areas of land associated with higher rate of soil loss and enhanced erosion vulnerability. The linearity in the spatial pattern is correlated with the development of logging roads and logging activities which has been confirmed by the extraction of exposed areas from satellite images of different years of analysis. The findings of the present study has quantified the changes in vegetation cover from dense, thick tropical forest to open mixed type landscapes which provide less protection against erosion and soil loss during the severe rainfall events which are characteristic of this tropical region. 相似文献
18.
King Talal Dam (KTD) watershed is the most important one in Jordan. At its outlet lies the KTD (80 MCM capacity) which serves
irrigation purposes in the Jordan Valley. However, the dam suffers from accelerated annual sedimentation. Therefore, this
study is directed to assess the erosion risk over the watershed, and to simulate actual annual sediment yield at the dam in
order to devise the appropriate conservation practices. Generalized assessment was first conducted over the watershed on the
basis of drainage texture, rainfall erosion index (R), and the ratio p2/P. As a result, the watershed is divided into zones of severe, high (gullying), high (overland flow) and low erosion risk.
Sediment yield at the dam was evaluated by a simulation model. For model validation the simulation results were compared to
the measured values over 12 years period, and a good agreement was obtained in some of the years. The simulation results allow
us to assess the application of two practical conservation practices: terracing and plantation of trees.
Received: 18 November 1997 · Accepted: 18 May 1998 相似文献
19.
Mauro A. E. Chaparro Marcos A. E. Chaparro Ana M. Sinito 《Environmental Earth Sciences》2012,66(5):1477-1485
In this contribution, a methodology is reported in order to build an interval fuzzy model for the pollution index PLI (a composite index using relevant heavy metal concentration) with magnetic parameters as input variables. In general, modelling based on fuzzy set theory is designed to mimic how the human brain tends to classify imprecise information or data. The “interval fuzzy model” reported here, based on fuzzy logic and arithmetic of fuzzy numbers, calculates an “estimation interval” and seems to be an adequate mathematical tool for this nonlinear problem. For this model, fuzzy c-means clustering is used to partition data, hence the membership functions and rules are built. In addition, interval arithmetic is used to obtain the fuzzy intervals. The studied sets are different examples of pollution by different anthropogenic sources, in two different study areas: (a) soil samples collected in Antarctica and (b) road-deposited sediments collected in Argentina. The datasets comprise magnetic and chemical variables, and for both cases, relevant variables were selected: magnetic concentration-dependent variables, magnetic features-dependent variables and one chemical variable. The model output gives an estimation interval; its width depends on the data density, for the measured values. The results show not only satisfactory agreement between the estimation interval and data, but also provide valued information from the rules analysis that allows understanding the magnetic behaviour of the studied variables under different conditions. 相似文献