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2022年3月17日,山西省交口县某铝矿尾矿库发生溃坝事故,造成较大经济损失。为了探究尾矿库溃坝的原因,基于多时相光学卫星立体像对数据和SBAS-InSAR等遥感技术,回溯分析该尾矿库的堆载过程、库容变化和坝体形变,并采用GeoStudio软件Slope/W模块评价溃坝前边坡的稳定性。结果表明:(1)该尾矿库于2019年9月前已堆积至最大库容,2021年12月前在2#坝后方子库堆载至96万m3,超出设计库容4.8万m3,从而降低了坝体的稳定性;(2)溃坝物源主要来自2#坝以上库区,在2#坝与1#坝之间以及1#坝到沟口区域均主要以堆积为主;(3)该尾矿库溃坝属于典型的渗流场诱发尾矿坝失稳,尾矿加载导致其坝体边坡稳定性安全系数由1.125降至0.991,是该尾矿库溃坝的直接诱发因素。 相似文献
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Abstract Small dams represent an important local-scale resource designed to increase water supply reliability in many parts of the world where hydrological variability is high. There is evidence that the number of farm dams has increased substantially over the last few decades. These developments can have a substantial impact on downstream flow volumes and patterns, water use and ecological functioning. The study reports on the application of a hydrological modelling approach to investigate the uncertainty associated with simulating the impacts of farm dams in several South African catchments. The focus of the study is on sensitivity analysis and the limitations of the data that would be typically available for water resources assessments. The uncertainty mainly arises from the methods and information that are available to estimate the dam properties and the water use from the dams. The impacts are not only related to the number and size of dams, but also the extent to which they are used for water supply as well as the nature of the climate and the natural hydrological regimes. The biggest source of uncertainty in South Africa appears to be associated with a lack of reliable information on volumes and patterns of water abstraction from the dams. Citation Hughes, D. A. & Mantel, S. K. (2010) Estimating the uncertainty in simulating the impacts of small farm dams on streamflow regimes in South Africa. Hydrol. Sci. J. 55(4), 578–592. 相似文献
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Many concrete gravity dams have been in service for over 50 years, and over this period important advances in the methodologies for evaluation of natural phenomena hazards have caused the design‐basis events for these dams to be revised upwards. Older existing dams may fail to meet revised safety criteria and structural rehabilitation to meet such criteria may be costly and difficult. Fragility assessment provides a tool for rational safety evaluation of existing facilities and decision‐making by using a probabilistic framework to model sources of uncertainty that may impact dam performance. This paper presents a methodology for developing fragilities of concrete gravity dams to assess their performance against seismic hazards. The methodology is illustrated using the Bluestone Dam on the New River in West Virginia, which was designed in the late 1930s. The seismic fragility assessment indicated that sliding along the dam–foundation interface is likely if the dam were to be subjected to an earthquake with a magnitude of the maximum credible earthquake (MCE) specified by the U.S. Army Corps of Engineers. Moreover, there will likely be tensile cracking at the neck of the dam at this level of seismic excitation. However, loss of control of the reservoir is unlikely. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Geochemical Distribution of Trace Elements in Groundwater from the North Mara Large‐Scale Gold Mining Area of Tanzania 
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下载免费PDF全文 Mwemezi Johaiven Rwiza Kyoung‐Woong Kim Sang‐don Kim 《Ground Water Monitoring & Remediation》2016,36(2):83-93
The influence of large‐scale mining operations on groundwater quality was investigated in this study. Trace element concentrations in groundwater samples from the North Mara mining area of northern Tanzania were analyzed. Statistical analyses for relationships between elemental concentrations in the samples and distance of a sampling site from the mine tailings dam were also conducted. Eleven trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined, and averages of Fe and Al concentrations were higher than levels accepted by the Tanzanian drinking water guideline. Levels of Pb in three samples were higher than the World Health Organization (WHO) and United States Environmental Protection Agency (USEPA) drinking water guidelines of 10 and 15 µg/L, respectively. One sample contained a higher As level than the WHO and USEPA guideline of 10 µg/L. The correlation between element concentrations and distance from the mine tailings dam was examined using the hierarchical agglomeration cluster analysis method. A significant difference in the elemental concentration existed depending on the distance from the mine tailings dam. Mann–Whitney U‐test post hoc analysis confirmed a relationship between element concentration and distance of a sampling site from the mine tailings dam. This relationship raises concerns about the increased risks of trace elements to people and ecosystem health. A metal pollution index also suggested a relationship between elemental concentrations in the groundwater and the sampling sites’ proximity from the mine tailings dam. 相似文献
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As an efficient tool in handling uncertain issues, Dempster-Shafer evidence theory has been increasingly used in structural health monitoring and damage detection. In applications, however, Dempster-Shafer evidence theory sometimes leads to counter-intuitive results. In this study, a new fusion algorithm of evidence theory is put forward to address various counter-intuitive problems and manage the reliability difference of the evidence. The proposed algorithm comprises the following aspects:(1) Dempster's combination rule is generalized by introducing the concept of evidence ullage. The new rule allows classical Dempster's rule and can resolve counter-intuitive problems cause by evidence conflict and evidence compatibility;(2) a reliability assessing method based on a priori and posterior knowledge is proposed. Compared with conventional reliability assessment, the proposed method can reflect the actual evidence reliabilities and can efficiently reduce decision risk. Numerical examples confirm the validity and utility of the proposed algorithm. In addition, an experimental investigation on a spatial truss structure is carried out to illustrate the identified ability of the proposed approach. The results indicate that the fusion algorithm has no strict request on the accuracy and consistency of evidence sources and can efficiently enhance diagnostic accuracy. 相似文献
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针对地震(或静力)液化作用对尾矿坝渗流场和孔压分布的影响进行研究,基于多孔介质渗流理论,考虑到尾矿坝渗流特性,编写分析程序SAFTD。根据程序假设的初始浸润面,通过调整浸润面处网格迭代求解最终浸润面的位置,选取一个经典算例验证程序的可靠性。针对典型的上游法尾矿库,采用SAFTD程序分析液化前后尾矿坝的渗流场与孔压分布特征。数值模拟结果表明,液化后尾矿坝的浸润面中间部分发生明显抬升,而在入渗点处和出渗点附近变化不大;液化后尾矿坝的孔压明显增加,坝体内部孔压增大约18%~280%,最大的孔压增量发生在初期坝的右下部,数值模拟结果与Ishihara对Mochikoshi 2号坝的分析结果相似。 相似文献
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Hydrological risk analysis is essential and provides useful information for dam safety management and decision-making. This study presents the application of bivariate flood frequency analysis to risk analysis of dam overtopping for Geheyan Reservoir in China. The dependence between the flood peak and volume is modelled with the copula function. A Monte Carlo procedure is conducted to generate 100,000 random flood peak-volume pairs, which are subsequently transformed to corresponding design flood hydrographs (DFHs) by amplifying the selected annual maximum flood hydrographs (AMFHs). These synthetic DFHs are routed through the reservoir to obtain the frequency curve of maximum water level and assess the risk of dam overtopping. Sensitive analysis is performed to investigate the influence of different AMFH shapes and correlation coefficients of flood peak and volume on estimated overtopping risks. The results show that synthetic DFH with AMFH shape characterized by a delayed time to peak results in higher risk, and therefore highlight the importance of including a range of possible AMFH shapes in the dam risk analysis. It is also demonstrated that the overtopping risk is increased as the correlation coefficient of flood peak and volume increases and underestimated in the independence case (i.e. traditional univariate approach), while overestimated in the full dependence case. The bivariate statistical approach based on copulas can effectively capture the actual dependence between flood peak and volume, which should be preferred in the dam risk analysis practice. 相似文献
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Representation and quantification of uncertainty in climate change impact studies are a difficult task. Several sources of uncertainty arise in studies of hydrologic impacts of climate change, such as those due to choice of general circulation models (GCMs), scenarios and downscaling methods. Recently, much work has focused on uncertainty quantification and modeling in regional climate change impacts. In this paper, an uncertainty modeling framework is evaluated, which uses a generalized uncertainty measure to combine GCM, scenario and downscaling uncertainties. The Dempster–Shafer (D–S) evidence theory is used for representing and combining uncertainty from various sources. A significant advantage of the D–S framework over the traditional probabilistic approach is that it allows for the allocation of a probability mass to sets or intervals, and can hence handle both aleatory or stochastic uncertainty, and epistemic or subjective uncertainty. This paper shows how the D–S theory can be used to represent beliefs in some hypotheses such as hydrologic drought or wet conditions, describe uncertainty and ignorance in the system, and give a quantitative measurement of belief and plausibility in results. The D–S approach has been used in this work for information synthesis using various evidence combination rules having different conflict modeling approaches. A case study is presented for hydrologic drought prediction using downscaled streamflow in the Mahanadi River at Hirakud in Orissa, India. Projections of n most likely monsoon streamflow sequences are obtained from a conditional random field (CRF) downscaling model, using an ensemble of three GCMs for three scenarios, which are converted to monsoon standardized streamflow index (SSFI-4) series. This range is used to specify the basic probability assignment (bpa) for a Dempster–Shafer structure, which represents uncertainty associated with each of the SSFI-4 classifications. These uncertainties are then combined across GCMs and scenarios using various evidence combination rules given by the D–S theory. A Bayesian approach is also presented for this case study, which models the uncertainty in projected frequencies of SSFI-4 classifications by deriving a posterior distribution for the frequency of each classification, using an ensemble of GCMs and scenarios. Results from the D–S and Bayesian approaches are compared, and relative merits of each approach are discussed. Both approaches show an increasing probability of extreme, severe and moderate droughts and decreasing probability of normal and wet conditions in Orissa as a result of climate change. 相似文献
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A semi‐analytical approach for predicting peak discharge of floods caused by embankment dam failures 下载免费PDF全文
下载免费PDF全文 This study presents an analytical solution of dam‐break floods in a trapezoidal channel with detailed solution procedure. An approach predicting the peak discharge of floods caused by embankment dam failures was derived from the aforementioned analytical solution with a database of 27 historical dam failures. The prediction performance of this approach has been proved by comparing with other 14 straightforward equations for estimating the peak discharge. The proposed model with a small uncertainty of predicted peak flow rates has a high coefficient of determination and a small standard error, being ranked in the top four of the 15 methods considered in this paper. The robustness and predictive capability of the proposed model are further demonstrated in two case studies, and both were considered in the previous analyses performed by other investigators. This method provides a simple and transparent tool for engineers to predict the peak discharge and is easy to implement for trial and error calculation. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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There are several alternatives to evaluate seismic damage‐cracking behavior of concrete arch dams, among which damage theory is the most popular. A more recent option introduced for this purpose is plastic–damage (PD) approach. In this study, a special finite element program coded in 3‐D space is developed on the basis of a well‐established PD model successfully applied to gravity dams in 2‐D plane stress state. The model originally proposed by Lee and Fenves in 1998 relies on isotropic damaged elasticity in combination with isotropic tensile and compressive plasticity to capture inelastic behaviors of concrete in cyclic or dynamic loadings. The present implementation is based on the rate‐dependent version of the model, including large crack opening/closing possibilities. Moreover, with utilizing the Hilber–Hughes–Taylor time integration scheme, an incremental–iterative solution strategy is detailed for the coupled dam–reservoir equations while the damage–dependent damping stress is included. The program is initially validated, and then, it is employed for the main analyses of the Koyna gravity dam in a 3‐D modeling as well as a typical concrete arch dam. The former is a major verification for the further examination on the arch dam. The application of the PD model to an arch dam is more challenging because the governing stress condition is multiaxial, causing shear damage to become more important than uniaxial states dominated in gravity dams. In fact, the softening and strength loss in compression for the damaged regions under multiaxial cyclic loadings affect its seismic safety. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Discontinuous deformation analysis （DDA） provides a powerful numerical tool for the analysis of discontinuous media. This method has been widely applied to the 2D analysis of discontinuous deformation. However, it is hindered from analyzing 3D rock engineering problems mainly due to the lack of reliable 3D contact detection algorithms for polyhedra. Contact detection is a key in 3-D DDA analysis. The limitations and advantages of existing contact detection schemes are discussed in this paper, and a new approach, called the incision body （IB）, is proposed, taking into account the advantages of the existing methods. A computer code 3DIB, which uses the IB scheme as a 3D contact detection algorithm, was programmed with Visual C^＋＋. Static and dynamic stability analysis for three realistic engineering problems has been carried out. Furthermore, the focus is on studying the stability of a gravity dam on jointed rock foundation and dynamic stability of a fractured gravity dam subject to earthquake shaking. The simulation results show that the program 3DIB and incision body scheme are capable of detecting 3D block contacts correctly and hence simulating the open-close and slide process of jointed block masses. In addition, the code 3DIB could provide an effective tool for evaluating the safety of 3D dam structures, which is quite important for engineering problems. 相似文献
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Best practice land use planning and cost-effective tools to assure safety downstream of private dams
Communities are at threat because of the potential severe consequences of private dam failure. Such threat exists due to inadequate land use planning and safety assurance policy for water storage and downstream developments which must be integrated if lives and public and private property are to be saved. This paper aims to explore the interrelated policy, responsibility, cost-sharing and engineering issues associated with farm dam safety to mitigate failure threats to both existing and future downstream developments. Key insights into the design of best-practice integrated land use planning and safety assurance policy are provided based on (1) review of practice in Australia and internationally, underpinned by relevant theoretical principles, and (2) development of a cost-effective flood safety review/design tool to help policy-makers address cost sharing issues. The novel guidance and tool developed can help jurisdictions world-wide address the threats associated with farm dams and both existing and future land developments. 相似文献
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The response to warming of tropical low-level clouds including both marine stratocumulus and trade cumulus is a major source of uncertainty in projections of future climate. Climate model simulations of the response vary widely, reflecting the difficulty the models have in simulating these clouds. These inadequacies have led to alternative approaches to predict low-cloud feedbacks. Here, we review an observational approach that relies on the assumption that observed relationships between low clouds and the “cloud-controlling factors” of the large-scale environment are invariant across time-scales. With this assumption, and given predictions of how the cloud-controlling factors change with climate warming, one can predict low-cloud feedbacks without using any model simulation of low clouds. We discuss both fundamental and implementation issues with this approach and suggest steps that could reduce uncertainty in the predicted low-cloud feedback. Recent studies using this approach predict that the tropical low-cloud feedback is positive mainly due to the observation that reflection of solar radiation by low clouds decreases as temperature increases, holding all other cloud-controlling factors fixed. The positive feedback from temperature is partially offset by a negative feedback from the tendency for the inversion strength to increase in a warming world, with other cloud-controlling factors playing a smaller role. A consensus estimate from these studies for the contribution of tropical low clouds to the global mean cloud feedback is 0.25 ± 0.18 W m?2 K?1 (90% confidence interval), suggesting it is very unlikely that tropical low clouds reduce total global cloud feedback. Because the prediction of positive tropical low-cloud feedback with this approach is consistent with independent evidence from low-cloud feedback studies using high-resolution cloud models, progress is being made in reducing this key climate uncertainty. 相似文献
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Usage of any single attribute would introduce unacceptable uncertainty due to limited reservoir thickness and distribution, and strong lateral variations in lithological traps. In this paper, a wide range of prestack and post-stack seismic attributes is utilized to identify a range of properties of turbidity channel sandstone reservoir in Block L118 of J Oilfield, China. In order to better characterize the turbidity channel and lower the uncertainty, we applied multi-attribute fusion to weight a variety of seismic attributes in terms of their relevance to the identification of turbidity channel reservoir. Turbidity channel boundary is clearly present in the new attribute and the reservoir thickness prediction is improved. Additionally, fluid potential of reservoir was predicted using this fused attribute with a high value anomaly indicating high fluid potential. The multi-attribute fusion is a valid approach for the fine prediction of lithologic reservoirs, reducing the risks typically associated with exploration. 相似文献
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Video-based hydrometry continues to develop for contactless discharge measurements, automated flood gauging stations and the use of crowd-sourced flood videos for discharge reconstruction. Irrespective of the velocimetry algorithm used (LSPIV, STIV, PTV…), orthorectification of the images is necessary beforehand, so that each pixel has the same known physical size. Most times, the orthorectification transformation is a plane-to-plane projection from the water surface to the camera sensor. Two approaches are typically used to compute the coefficients of this transformation: their calibration from ground reference points (GRPs) with known image and real-world coordinates (“implicit calibration”) or their calculation from the values of the intrinsic (focal length, sensor size) and extrinsic (position, angles) parameters of the camera (“explicit calibration”). In this paper, we develop a Bayesian method which makes it possible to combine the implicit and explicit approaches in a probabilistic framework. The Bayesian approach can be used from situations suitable for the implicit approach (plenty of GRPs) to situations propitious to the explicit approach (well-known camera parameters). The method is illustrated using synthetic views of a typical streamgauging scene with known true values of the parameters and GRP coordinates. We show that combining observational and prior information is generally beneficial to get precise estimates. Further tests carried out with a real scene of the Arc River at Randens, France, in flood conditions illustrate the impact of the number, uncertainty and spatial distribution of GRPs on the final uncertainty of flow velocity and discharge. 相似文献
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地面核磁共振方法是一种直接探测地下水信息的地球物理勘查方法,本文将该无损探测技术用于土石坝的渗流安全评估试验。由于探测的核磁共振信号源于地下水中的氢质子,则可以确保核磁共振响应仅与地下水信息有关。利用地面核磁共振方法直接找水的技术优势,探测堤坝的浸润面,以判断堤坝的渗流(漏)隐患,为堤坝尤其是小型病险水库堤坝、易发事故的堤防的病险诊断提供一种便捷、高效和可重复利用的方法。通过NUMISPOLY多道核磁共振探测系统在某原体大坝检测中的试验,得到原体大坝的浸润面,进而对土石坝进行渗流(漏)隐患的评估,该方法为堤坝渗流(漏)隐患探测提供了一种有效而可靠的新方法。 相似文献
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火山灰云不但引起全球气候和环境系统的重大变化,而且还会威胁航空安全。热红外遥感技术为检测火山灰云提供了新手段,但是遥感数据自身的冗余和波段相关性大大降低了火山灰云的检测精度。独立分量分析(Independent Component Analysis,ICA)能够实现遥感数据的去相关和消除冗余,在火山灰云检测中具有一定的潜力。通过探索火山灰云的物理、化学性质,文中以2010年4月19日冰岛艾雅法拉(Eyjafjallajokull)火山灰云MODIS图像为数据源,在对MODIS数据进行主成分分析处理的基础上,利用ICA进行火山灰云检测。结果表明:ICA能够较好地从MODIS图像中获取火山灰云信息,所得结果与美国地质调查局标准光谱数据库和火山灰云SO2浓度分布具有较好的一致性,取得了较好的检测效果。 相似文献
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Abstract The increasing demand for water in southern Africa necessitates adequate quantification of current freshwater resources. Watershed models are the standard tool used to generate continuous estimates of streamflow and other hydrological variables. However, the accuracy of the results is often not quantified, and model assessment is hindered by a scarcity of historical observations. Quantifying the uncertainty in hydrological estimates would increase the value and credibility of predictions. A model-independent framework aimed at achieving consistency in incorporating and analysing uncertainty within water resources estimation tools in gauged and ungauged basins is presented. Uncertainty estimation in ungauged basins is achieved via two strategies: a local approach for a priori model parameter estimation from physical catchment characteristics, and a regional approach to regionalize signatures of catchment behaviour that can be used to constrain model outputs. We compare these two sources of information in the data-scarce region of South Africa. The results show that both approaches are capable of uncertainty reduction, but that their relative values vary. Editor D. Koutsoyiannis Citation Kapangaziwiri, E., Hughes, D.A., and Wagener, T., 2012. Incorporating uncertainty in hydrological predictions for gauged and ungauged basins in southern Africa. Hydrological Sciences Journal, 57 (5), 1000–1019. 相似文献