نشریه سد و نیروگاه برق آبی ایران
پیاپی 10 (پاییز 1396)

There are a number of uncertainties in estimating reservoir sedimentation and accumulation which are related to amount of streamflow, sediment load, sediment particle size, specific weight, trap efficiency and reservoir operation. In this study, to analyze the uncertainty of annual reservoir sedimentation, the accumulated reservoir sedimentation data for 46 years has been used and an empirical model to estimate the volume of reservoir sedimentation based on Fuzzy α-cut method has been developed in MATLAB software environment. Two fuzzy membership function with five level of α-cut have been used to calculate the uncertainty annual reservoir sedimentation, trap efficiency and accumulated reservoir sedimentation. The calculated uncertainty is about 0.641, 0.023, 0.344, respectively. The results have shown that the streamflow has an important role in uncertainty, i.e. uncertainty increases while the streamflow is increased. Sediment load factor and the trap efficiency have the most and least effects on uncertainty of Latian reservoir sedimentation volume estimate, respectively.

Compared to the preliminary forecasted values, the fluctuation in the final cost and time of civil engineering projects is an issue exists in all of the countries in the world. These fluctuations will possibly result in many claims; therefore, they should be controlled. Forecasting is an important tool for controlling the fluctuations in the cost and time of a project. One of the standard methods for forecasting the time and cost of a project is the earned value analysis; also, modeling with the help of artificial neural networks is another standard forecasting method which is currently popular. In this paper, a model is created by considering several variables from the basic variables and the performance indices of the EVA as input variables without using any type of coding and only using the nftool in Matrix Laboratory software. Without any affiliation on the type of project, this model is capable of forecasting the cost of projects whose cost is higher than the budget (most of the civil engineering projects executed in Iran); the model does so with a higher accuracy compared to the cost forecast relations in the EVA. It should be noted that two water transmission channel projects and two dam projects (executed in Iran) were used to experiment this model. The findings of this experiment showed that the model is highly accurate.

Jet diffusion in plunge pool is one of the research topics of many researchers. Most of these researches were done experimentally and few of them were done numerically. In this study, jet diffusion in plunge pool is simulated by using FLOW3D software. Result of models show that this software has a high capability in predicting of jet diffusion characteristics such as velocity profiles and diffusion angles in free jet and impinging regions. The height of impinging region in numerical model is very close to experimental results. Numerical model results have shown that angles of jet diffusion i.e. outer spread angle and inner core decay angle are 5 to 11° and 9 to 12°, respectively. Numerical model predicts the normalized mean pressure (Cp) equal to 1.0 in the plunge pool floor when core jet meets the plunge pool floor whereas this parameter is less than 1.0 in the experimental model because of air entrainment to plunge pool. Moreover, normalized pressure profiles in the plunge pool floor has similar results with experimental cases.

The aim of this research is establishing healthy, safety and environment management system in construction phase of a dam in Northern Zagros zone. Methods are based on three steps. The first step is risk factor identification. In this step, it has been studied which risks are caused by activities in operation phase in the three group of physical-chemical risk, biological risk and human risk. The second step is risk assessment. The risks are introduced in three criteria, severity, probability and vulnerability, and the environmental risk parameters have been scored by using expert opinion. The risks were prioritized by using Entropy method and TOPSIS Solver 2014 software. The results have shown that in the construction phase, reduction of aquatic life, destruction of vegetation and workers fall are of high risk. Moreover, in the third step the Healthy, Safety and Environment Managment System (HSE-MS) program is proposed in five steps. The first step is policy and objective. The second step is offering environment, health and safety plan. The third step is program implementation. The fourth step is monitoring and control on program, quality air, sewage and residue. The fifth step is reviewing the program implementation problem changing the monitoring plan.

Since the fishway serves important roles in fish migration and survival, they are the main components of river cross structures like dams. In this study, the numerical modeling of Canoe-fishways was conducted using Flow-3D software. For verification, it was used as the results of experimental modeling. By comparing numerical results with experimental model, it was found that the error rates for the depth and velocity of flow were 3 and 11.5%, respectively. Then, using numerical models, the velocity of flow was shown in different directions for optimization discharges, a low-velocity area in pools was found after each brush was formed which was the best place for resting of migratory fishes. Providing the amount of turbulence in different parts of the canal, it was determined that the maximum turbulence occurred in the canal slot. The maximum velocity occurred in slot and in pool front slot. It was also found that velocity and turbulence in different parts of the canal were within the allowable range.

In this research the effects of nonlinear behavior of concrete on seismic performance of double curvature arch dam have been investigated. ANSYS software was used for analysis of the model which is based on finite element method. The Morrow Point double curvature arch dam is selected as the seismic analysis case study model and the interaction effect of dam, reservoir and foundation has been considered in the model. To investigate the seismic behavior of dam the El Centro earthquake components has been applied to the model. Both linear and nonlinear behavior of concrete has been investigated by dynamic analysis separately. Results of the displacement of dam crest and principle stresses have been extracted and compared. The results of the analysis have shown the effects of nonlinearity behavior of the concrete on the responses which means that the nonlinearity behavior of concrete would increase the displacement of dam crest and decrease principle stresses. The results have shown that by applying the nonlinearity behavior of concrete, the maximum structural capacity can be used which leads to increasing the accuracy in the field of linearity and nonlinearity material behavior to offer optimal models.