نشریه سد و نیروگاه برق آبی ایران
پیاپی 18 (پاییز 1397)

Abstract:The marash dam is located on the halab River near the village of Marash, 125 km from Zanjan and 1800 meters from Dandi city. The purpose of this research is to identify and assess the environmental risk of the Marash dam in operation and construction phase. In this Reasearch, after collecting and reviewing information about the environmental conditions of the study area and determining the types of activities and processes in the implementation and operation phase, a list of possible environmental risk factors was prepared by a questionnaire, and in order to check its accuracy was provided to an expert group including elites and professors in the field of environmental and dam Construction. To integrate comments and final identification of risk factors, by SPSS software, the geometric mean of important risk factors was calculated. After analyzing the given points using the findings of FANP and FTOPSIS, ranking and prioritizing the risk of the Marash dam was used and the final risks of the dam were identified. Among 19 risk factors, options for the economic environment that included employment and income, non-immigration and the development of future plans in both types of evaluation were prioritized over other options and among the negative effects of the project, habitat demolition and water pollution are the most important risk factors that are prioritized over other negative options. And authorities should put them on the consideration in their plans.

In this paper, the effect of using modified trenches on the load-bearing capacity of the soil and the effect of its dimensions using numerical analysis with ABAQUS software based on the finite element method has been investigated. The software validation has been compared with previous studies, and after ensuring that the results are matched, the effect of the improved trench has been investigated. Based on the analysis of the modified trench load bearing capacity, it has been concluded that, in general, soil improvement using trench with higher resistance properties beneath foundations, soil bearing capacity has increased and the soil exhibits more resistance, and by increasing the ratio of the trench width to the width of the foundation about three times, its value increases. Also, by changing the height of the trench, it can be used to optimize the load capacity and by determining the depth of drilling according to the design considerations, the cost of the operation is also reduced. The geometry and the shape of the foundations on the trench, as well as the characteristics of the trench, have a significant impact on its bearing capacity, therefore they can be optimally loaded with proper selection.

In this paper one of the newest meta-heuristic algorithms named Gravitational Search Algorithm (GSA) is used to optimal design of stepped spillway with minimizing cost. Generally, dam construction projects classify as expensive projects in which the related high costs should be reduced. Dams consist of different structures. One of these structures is energy dissipater structure. Generally, different structure such as spillway have been used for energy dissipation. Here, stepped spillway is considered as an energy dissipater structure. Therefore, GSA is used here for optimizing the excavation and concrete costs and reducing the final costs of this structure. With the use of MATLAB software for GSA coding, the Tehri dam in India is considered here as a case study and the construction cost is reduced using GSA so that all of the hydraulic constraints will be satisfied. In the following, the obtained results of GSA are compared with the results of Genetic Algorithm (GA) and Vittal and Porey (VP) approach. Comparing the results of VP approach with two used algorithms indicates that when the spillway has four steps, the results of GA and GSA are improved respectively 6% and 7.6% than the results of VP and the results of GSA are improved 1.8% than the results of GA.

Overtopping is the most reasons of dam break, particularly for embankment dams. The fuse plug is used as a safety valve to protect the dam from catastrophic failurs caused by overtopping flow. In this experimental study, using a series of experimental tests, the effect of plug fuse washout on the outflow discharge from the dam reservoir due to change the width and depth of the pilot channel has been investigated. The results of this experimental study are the outflow hydrograph resulting from the overtopping flow the change in width and depth of the pilot channel. The type of development of the embankment breach was different due to surface erosion and headcut erosion. Also, the effect of changes in the outflow discharge more dependent on the depth of the pilot channel than the pilot channel width, in such a way that the pilot channel width changes can be ignored within the range of parameters in this study. According to the obtained results, the optimum depth and width of the pilot channel were determined.

In the present research a comparison of estimation has been made for suspended sediment load in storage dams using methods of Artificial Neural Network (ANN) and Artificial Neural Network Fuzzy Inference System (ANFIS). The daily average discharges of Sefidroud River (at north of Iran) were used as the model inputs and its sediments concentration in time series as the outputs by utilizing MATLAB program. Out of 229 available data, 182 were applied as training data and the rest (47 data) as testing data. The inputs and outputs of sediment concentration had positive procedures. Eighty percent (80%) of the available data have been used for the training while the remaining used for testing network. The results showed that the concentration prediction of the suspended sediment loads obtained from the ANFIS were closer to the available sediment concentrations. The regression coefficient was ninety percent (90%) for the ANFIS while that for the ANN was eighty three percent (83%). Therefore, it could be concluded that as for concentration prediction of the suspended sediment loads the ANFIS is more efficient than the ANN.

Soil mass saturation leads to unstable support and will landslip into reservoir. Movement and deformation of soil mass in a saturated environment and wave resulting of it could result in changes in hydraulic parameters in dam storage. In this relation interaction between water and land sliding mass has been studied by dam scientists. In this study mass movement on slop bed (landslide) has been modeled as non-Newtonian fluid in which has been interacted with a Newtonian fluid (water). For this, SPHysics2D Lagrangian meshless smoothed particle hydrodynamics (SPH) code has been developed. For modeling sediments and their movement investigation Herschel Bulkley Papanastasiou non-Newtonian viscoplastic model has been utilized. First for integrity evaluation of rheological model was performed using granular dam break experimental data. After that landslide was modeled as drowned form and the results were compared to experimental data. The results of developed model show suitable simulation of this group of two-phase problems which are widely questioned by hydraulic and geological engineers.

In the past two decades, using different methods and techniques for the implementation and management of construction projects has increased dramatically. Not only has the success rate of projects had appropriate progress, but also we have faced with schedule delays, increased costs, poor quality and increased number of claims and litigation. Nowadays major concern of many project managers is to complete the project on time and on budget in complex environment. Maybe we find out some environmental factors that impact on it, while the project managers do not consider that in critical situation. This research introduces the complex environment of construction projects and explains different types of complexity in order to achieve those factors. The main purpose of this paper is to identify complexity factors of project time management within the PMBOK process. In addition to proving complex and chaotic environment of project time management, we introduce these factors. Effective Parameters will be recognized and we should consider those in project planning and control, those are ignored in most of the projects and cause difficulty. Clarifying the problem and significant impacts on the implementation process will be represented the appropriate approach on project time management.