高速公路下伏采空区地表变形预计及稳定性评价   总被引：1，自引：0，他引：1  

吴盛才  徐鹏  贺跃光 《测绘科学》2012,37(2):97-99

高速公路下伏采空区是路基路面及桥梁工程的严重隐患。高速公路下伏采空区在探测、排查的基础上,进行采空区稳定性评价,需对其地表各种变形值进行预计。本文采用概率积分法对采空区地表移动与变形值进行预计,计算并绘制出采空区主断面上的变形曲线;进而根据预计后的变形曲线,对采空区的稳定性做出准确的评价。实例预计结果表明,水平变形、地表倾斜和曲率均超过变形控制指标,采空区欠稳定,并以预计结果作为设计经济可行、技术可行的高速公路下伏采空区治理方案的依据。  相似文献   

基于马尔科夫网视频图像目标检测跟踪方法研究     

曹建农  李德仁  关泽群 《测绘科学》2004,29(6):45-49

研究了马尔科夫网的概念、方法,分析它在空间数据挖掘中的作用与意义,并以视频图像为例广泛研究以多种粒度(节点数)建立视频图像间的马尔科夫网,通过网络结构分析检测视频图像中的目标差异。研究表明马尔科夫网可以很好地揭示数据间的抽象近邻关系,并且这种网络自身就具有表达知识的意义。  相似文献   

An event simulation approach to the assessment of flood level frequencies: risk maps for the Warsaw reach of the River Vistula          下载免费PDF全文

R. J. Romanowicz  A. Kiczko 《水文研究》2016,30(14):2451-2462

Flood risk assessment is customarily performed using a design flood. Observed past flows are used to derive a flood frequency curve which forms the basis for a construction of a design flood. The simulation of a distributed model with the 1‐in‐T year design flood as an input gives information on the possible inundation areas, which are used to derive flood risk maps. The procedure is usually performed in a deterministic fashion, and its extension to take into account the design flood‐and flow routing model uncertainties is computer time consuming. In this study we propose a different approach to flood risk assessment which consists of the direct simulation of a distributed flow routing model for an observed series of annual maximum flows and the derivation of maps of probability of inundation of the desired return period directly from the obtained simulations of water levels at the model cross sections through an application of the Flood Level Frequency Analysis. The hydraulic model and water level quantile uncertainties are jointly taken into account in the flood risk uncertainty evaluation using the Generalized Likelihood Uncertainty Estimation (GLUE) approach. An additional advantage of the proposed approach lies in smaller uncertainty of inundation predictions for long return periods compared to the standard approach. The approach is illustrated using a design flood level and a steady‐state solution of a hydraulic model to derive maps of inundation probabilities. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Probabilistic assessment of one‐step‐ahead rainfall variation by Split Markov Process     

Rajib Maity 《水文研究》2012,26(21):3182-3194

In this paper, Split Markov Process (SMP) is developed to assess one‐step‐ahead variation of daily rainfall at a rain gauge station. SMP is an advancement of general Markov Process and specially developed for probabilistic assessment of change in daily rainfall magnitude. The approach is based on a first‐order Markov chain to simulate daily rainfall variation at a point through state/sub‐state transitional probability matrix (TPM). The state/sub‐state TPM is based on the historical transitions from a particular state to a particular sub‐state, which is the basic difference between SMP and general Markov Process. The cumulative state/sub‐state TPM is represented in a contour plot at different probability levels. The developed cumulative state/sub‐state TPM is used to assess the possible range of rainfall in next time step, in a probabilistic sense. Application of SMP is investigated for daily rainfall at four rain gauge stations – Khandwa, Jabalpur, Sambalpur, and Puri, located at various parts in India. There are 99 years of record available out of which approximately 80% of data are used for calibration, and 20% of data are used to assess the performance. Thus, 80 years of daily monsoon rainfall is used to develop the state/sub‐state TPM, and 19 years data are used to investigate its performance. Model performance is assessed in terms of hit rate (HR), false alarm rate (FAR), and percentage captured. It is found that percentage captured is maximum for Khandwa (70%) and minimum for Sambalpur (44%) whereas hit rate is maximum for Sambalpur and minimum for Khandwa (73%). FAR is around 30% or below for Jabalpur, Sambalpur, and Puri. FAR is maximum for Khandwa (37%). Overall, the assessed range, particularly the upper limit, provides a quantification possible extreme value in the next time step, which is a very useful information to tackle the extreme events, such as flooding, water logging and so on. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Neural network prediction of the reliability of heterogeneous cohesive slopes          下载免费PDF全文

Y.H. Chok  M.B. Jaksa  W.S. Kaggwa  D.V. Griffiths  G.A. Fenton 《国际地质力学数值与分析法杂志》2016,40(11):1556-1569

The reliability of heterogeneous slopes can be evaluated using a wide range of available probabilistic methods. One of these methods is the random finite element method (RFEM), which combines random field theory with the non‐linear elasto‐plastic finite element slope stability analysis method. The RFEM computes the probability of failure of a slope using the Monte Carlo simulation process. The major drawback of this approach is the intensive computational time required, mainly due to the finite element analysis and the Monte Carlo simulation process. Therefore, a simplified model or solution, which can bypass the computationally intensive and time‐consuming numerical analyses, is desirable. The present study investigates the feasibility of using artificial neural networks (ANNs) to develop such a simplified model. ANNs are well known for their strong capability in mapping the input and output relationship of complex non‐linear systems. The RFEM is used to generate possible solutions and to establish a large database that is used to develop and verify the ANN model. In this paper, multi‐layer perceptrons, which are trained with the back‐propagation algorithm, are used. The results of various performance measures indicate that the developed ANN model has a high degree of accuracy in predicting the reliability of heterogeneous slopes. The developed ANN model is then transformed into relatively simple formulae for direct application in practice. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Frequency analysis of annual maximum suspended sediment concentrations in Abiod wadi,Biskra (Algeria)          下载免费PDF全文

A. Benkhaled  H. Higgins  F. Chebana  A. Necir 《水文研究》2014,28(12):3841-3854

Sediment transport processes in the Mediterranean semi‐arid areas have interested a great number of hydrologists and statisticians. Frequency analysis (FA) procedures are commonly applied for several hydrological events such as floods and droughts. However, in general, FA is not widely applied to treat suspended sediment concentration (SSC), especially in semi‐arid regions. In the present study, an FA was performed on SSC data from 1979 to 1991 observed upstream from the Foum El Gherza dam, which is located at Biskra in the South–East of Algeria. This dam is problematic in terms of silting. Therefore, this study is mainly motivated by providing an FA model and risk evaluation in order to assist dam managers to better evaluate the potential of silting resulting from SSC transport to the reservoir. Probability distributions commonly used in hydrology were tested to SSC data recorded at the M'chounech station on Abiod wadi located upstream the dam. All the FA steps were considered; including classical techniques (e.g. goodness‐of‐fit tests, statistical criteria) as well as recently developed tools (tail distribution classification). Their application led to the selection of the lognormal distribution (LN2) to fit the considered data, and hence an accurate risk assessment could be obtained. Because of the presence of a slight trend, non‐stationary models are also considered in the present study. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

天津市降水特征及人影作业影响分析     

靳瑞军  王婉  宋薇  王兆宇 《气象》2011,37(1):92-98

利用天津市1986-2008年13个测站日降水资料,总结天津市降水特征并分析人影作业影响因子在其中产生的影响.结果表明:天津市降水空间分布不均匀,东西方向差异小,南北方向差异较大,雨量由北向南呈现递减趋势,且北部等值线密集,南部稀疏,雨量递减的速率由北向南减慢.降水季节性差异较大,降雨量和降雨日数都集中分布在夏季,春秋两季降雨次之,冬季降雨最少;人影作业未改变天津区域雨量相关系数,对空间分布影响较小,这与天津的作业特点有关;人影作业会对雨型概率分布产生影响,对1986-2001年和2002-2008年两个时期的各个雨型降雨日概率进行对比分析,结果表明,人影作业后的小雨降雨日概率相对较小,中雨以上的降雨日概率相对较高,但这些差别并不明显.  相似文献   

长期验潮站潮位观测误差的综合探测及修复方法研究     

赵建虎  柯灏  张红梅 《武汉大学学报(信息科学版)》2011,36(12):1490-1494

在分析潮位观测值中粗差和系统误差特点及现有检测和修复方法的基础上,提出了一种基于潮汐调和分析、概率论与数理统计相结合的潮位误差综合探测和修复方法。在长期潮位站实现了粗差和系统误差的准确探测和修复。  相似文献   

我国降水和气温的分级概率时空分布特征   总被引：1，自引：0，他引：1       下载免费PDF全文

杨小波  陈丽娟  刘芸芸 《应用气象学报》2011,22(5):513-524

采用全国160站1951—2009年月降水和气温资料,分析了短期气候预测业务评分办法中六级要素概率时空分布特征,并以1月、7月为代表获得了不同地区、不同级别降水和气温异常发生频率。结果表明:降水和气温的六级异常分布存在显著空间不均匀性和年代际变化特征,1980—2009年,北方降水在1月出现特少、特多等级和7月出现特少、偏少等级的概率较大,南方降水出现6个等级的概率基本相同;全国气温在1月和7月出现正常略低、正常略高和偏高等级的概率较大。1980—2009年与1951—1979年相比,全国1月降水为特多、偏多等级和7月降水为偏少等级的站数明显增加,全国1月气温为正常略高、偏高和特高等级的站数明显增加,呈明显的年代际变化特征。  相似文献   

震级离散下的震级频度关系          下载免费PDF全文

李忠华  秦嘉政  苏有锦 《地球物理学报》2011,54(4):1038-1042

运用最大熵原理,研究震级离散条件下震级频度关系,得到震级离散条件下震级概率分布函数,结果表明:(1)震级大于等于某一震级的地震次数应通过离散求和的方式得到,而不应通过积分的方式得到;(2)震级上限取为∞的情况下,古登堡意义和里克特意义两种震级频度关系式的b值相等;震级上限有限的情况下,里克特意义震级频度关系式可能不是直...  相似文献