This paper presents the main results from an investigation into the slope stability of unsaturated waste rock piles with various configurations and surface recharge conditions. The analyses first consider waste rock piles with different internal and external configurations, under steady-state conditions to evaluate the effect of the pile geometry on the factor of safety. Transient analyses are then conducted to evaluate the influence of rainfalls of different intensities and durations. For six waste rock pile configurations, the results illustrate how the external geometry of the pile influences the factor of safety. The results presented here show how surface infiltration (water recharge), external geometry, and internal pile features affect unsaturated water flow, pore water pressure (matric suction), and material strength, which in turn influence slope stability. Despite the relatively large imposed recharges, following major precipitation events, the results indicate that the decrease of the factor of safety FS is relatively small when compared with the effect of other influential factors. The results also demonstrate that the external geometry of the waste rock pile has the most significant impact on the factor of safety, indicating that pile stability can be controlled with an appropriate design. Waste rock piles with a uniform slope (single bench) should be avoided as this construction method leads to the lowest factor of safety. The overall results clearly demonstrate that the best way to improve the stability of waste rock piles is to use a design and construction method with benches of limited size.
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Rainfall threshold (RT) method is one of the evolving flood forecasting approaches. When the cumulative rainfall depth for a given initial soil moisture condition intersects the threshold rainfall curve, the peak discharge is expected to be equal or greater than the threshold discharge for flooding at the target site. Besides the total rainfall depth, spatial and temporal distribution of rainfall impacts the flood peak discharge and the time to peak. To revisit a previous study conducted by the authors, in which spatially independent rainfall pattern was assumed, the spatial distribution of rainfall was simulated following a Monte Carlo approach. The structure of the spatial dependence among sub‐watersheds' rainfalls was taken into account under three different scenarios, namely independent, bivariate copula (2copula) and multivariate Gaussian copula (MGC). For each set of generated random dimensionless rainfalls, the probabilistic RT curves were derived for dry moisture condition. Results were evaluated with both historical and simulated events. For the simulated events, threshold curves were assessed by means of categorical statistics, such as hit rate, false rate and critical success index (CSI). Results revealed that the best performance based on the CSI criterion corresponded to 50% curve in 2copula and MGC scenarios as well as 90% curve in the independent scenario. The recognition of 50% curve in 2copula and MGC scenarios is in agreement with our expectations that the mean probable curve should have the best performance. Moreover, the proposed inclusion of spatially dependent rainfall scenario improved the performance of RT curves by about 25% in comparison with the presumed spatially uniform rainfall scenario. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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The best available technology for small electroplating plants applying analytical hierarchy process 总被引：1，自引：1，他引：0
M. R. Dabaghian S. H. Hashemi T. Ebadi R. Maknoon 《International Journal of Environmental Science and Technology》2008,5(4):479-484
In this study analytical hierarchy process approach which uses expert’s knowledge, was applied for selection of the best wastewater treatment alternative for electroplating workshops, located in Tehran province, Iran. This method can be applied for complicated multi-criteria decision making to obtain scientific and reasonable results. Four wastewater treatment alternatives including reverse osmosis, nano filtration, ion exchange, and chemical precipitation were evaluated and ranked based on economical, technical, environmental/ social aspects. Each criterion includes different indices such as land area, capital cost, sludge disposal issues, operating and maintenance, local suppliers and warranty, system flexibility, required skilled and non skilled man power safety, and etc. The results showed that reverse osmosis achieved the maximum general profits and can be the best choice. Sensitivity analysis can shows the effect of inputs parameters change on the results. Sensitivity analysis was applied for each criterion. The results illustrated that for economic and technical criterion, chemical precipitation and for environment criterion, reverse osmosis were qualified. 相似文献
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Assessment of flood forecasting lead time based on generalized likelihood uncertainty estimation approach 总被引：3，自引：0，他引：3
A. Heidari B. Saghafian R. Maknoon 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,20(5):363-380
Real time updating of rainfall-runoff (RR) models is traditionally performed by state-space formulation in the context of flood forecasting systems. In this paper, however, we examine applicability of generalized likelihood uncertainty estimation (GLUE) approach in real time modification of forecasts. Real time updating and parameter uncertainty analysis was conducted for Abmark catchment, a part of the great Karkheh basin in south west of Iran. A conceptual-distributed RR model, namely ModClark, was used for basin simulation, such that the basin’s hydrograph was determined by the superposition of runoff generated by individual cells in a raster-based discretization. In real time updating of RR model by GLUE method, prior and posterior likelihoods were computed using forecast errors that were obtained from the results of behavioral models and real time recorded discharges. Then, prior and posterior likelihoods were applied to modify forecast confidence limits in each time step. Calibration of parameters was performed using historical data while distribution of parameters was modified in real time based on new data records. Two scenarios of rainfall forecast including prefect-rainfall-forecast and no-rainfall-forecast were assumed in absence of a robust rainfall forecast model in the study catchment. The results demonstrated that GLUE application could offer an acceptable lead time for peak discharge forecast at the expense of high computational demand. 相似文献
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