فرهود کلاته

Cavitation is a phenomenon during which, with the movement of the flow and the reduction of the liquid pressure to the saturated vapor pressure of the liquid in susceptible areas, bubbles of air are formed during the flow. The microjet becomes full of energy with the fluid, which when these micro jets collide with the walls, causing vibration and noise and destructive effects such as structural erosion of ship propellers, pump blades, and dams, as well as reducing efficiency, and malfunction of hydraulic devices. This research aims to study different simulation models of the cavitation phenomenon and compare them in the way of cavitation cloud creation and expansion and the effect of this phenomenon on the flow. The present research has been analyzed numerically using ANSYS FLUENT software. In this research, an attempt has been made to study and compare different cavitation models in various geometries. Also, in one example, the results of the numerical model have been compared with the results of the laboratory model. The results showed that the formation of cavitation phenomenon in 10 cm throat compared to 5 cm by 5.88%, in 10 cm throat compared to without throat by 64.71%, and in 5 cm throat compared to without throat by 5.62% has changed.

The performance of geomembrane liners depends on proper design, installation, and maintenance. Geomembranes exhibit thermoplastic behavior, expanding and contracting significantly with temperature changes. This can lead to issues like wrinkling and uplift, which can compromise the liner's seepage control function. Proper maintenance is also essential, as geomembranes are sensitive to mechanical damage that can greatly reduce their effectiveness.In Iran, geomembrane lining of irrigation canals has been implemented in several projects, including the Moghan Irrigation Network. However, comprehensive studies on the performance and durability of these liners are lacking. This study aimed to evaluate the effectiveness of geomembrane liners in controlling seepage from Pumping channel No. 3 of Moghan, and identify any issues related to their design, installation and operation. The results can help guide the rational expansion and optimal utilization of geomembrane lining for improving agricultural water productivity in Iran.

Literature Review:

Geomembranes exhibit thermoplastic behavior, expanding and contracting significantly with temperature changes. Geomembranes layers have a high coefficient of thermal expansion, causing wrinkling or waves in parts of the liner when heated. Proper temperature is critical for seam welding to avoid inadequate bonding and uplift of the geomembrane on slopes. Long-term wrinkles can also become failure points. Proper maintenance is essential for the sustainable operation of geomembrane projects, especially for exposed liners. Preventing mechanical damage (intentional and accidental) is crucial for the liner's durability and effectiveness. Geomembranes are sensitive to intentional damage (cutting, burning, abrasion, impact, etc.) which can greatly reduce the liner's seepage control capacity.

The Moghan irrigation network, particularly Pumping Channel No. 3, has been a focal point for evaluating hydraulic performance, seepage control, and durability in irrigation systems. This channel, which spans 28 kilometers, is crucial for drawing water from the irrigation network and has a capacity of 2.3 cubic meters per second, serving approximately 3,500 hectares of agricultural and industrial land. Research conducted on this channel has employed the inflow-outflow method to measure average seepage rates, which were found to be around 46.86 liters per day per square meter. This rate is considered moderate compared to other geosynthetic-lined channels, highlighting the need for ongoing maintenance and monitoring to manage water loss effectively.Field inspections have revealed significant deterioration in the channel's walls and floor, leading to operational challenges. In 1999, significant repairs were made to three critical sections of the canal, covering 8 kilometers in total. However, these repairs proved insufficient, as severe damage reoccurred within two years of service. This situation emphasizes the necessity for robust construction practices and the potential benefits of using advanced materials, such as geomembranes, to enhance the durability and performance of irrigation channels. The research indicates that while immediate repairs can address some issues, long-term solutions are essential for maintaining the integrity of the irrigation infrastructure.Overall, the evaluation of Pumping Channel No. 3 illustrates the complexities and challenges faced in managing irrigation systems, particularly regarding hydraulic efficiency and seepage control. The findings suggest that integrating geosynthetic materials could significantly improve the channel's performance and longevity, thereby optimizing water resource management in the Moghan region. Continuous assessment and adaptation of maintenance strategies will be crucial in ensuring that the irrigation network meets the agricultural demands of the area effectively.

The average seepage rate along the canal reaches was 0.4686 liters per square meter per day. No sedimentation or damage was observed during field inspections. The results demonstrate the acceptable short-term effectiveness of well-installed geomembrane liners in controlling water losses. Properly designed and maintained geomembrane liners can significantly reduce seepage, improving agricultural water productivity. However, geomembranes require careful consideration in design, construction and operation to avoid issues like thermal wrinkling and mechanical damage that can compromise their seepage control function.

Controlling seepage from water storage and conveyance systems is essential in water-scarce countries like Iran. Geosynthetic liners, especially geomembranes, are rapidly expanding in Iran due to their unique waterproofing capabilities and other advantages like quick and easy installation. However, comprehensive studies on the performance of these liners are lacking. Rational expansion, proper utilization and optimal investment requires comprehensive evaluation of completed projects. This study's results indicate the acceptable short-term effectiveness of well-installed geomembrane liners in controlling water losses. Therefore, geomembrane liners can contribute to improving agricultural water productivity by significantly reducing seepage, if they meet waterproofing requirements. However, long-term performance and durability require further investigation.

The cost of building dams is very high and their failure can be hazardous. On the other hand, they are vital for every country as freshwater storage. Deterministic and traditional algorithms can not answer the multidimensional and complex problems of dam construction, and it is necessary to use hybrid methods based on probabilities. The problems of fluid movement in their nature have a complexity that modeling and finding requires using an advanced algorithm that can finally interpret its non-deterministic nature. Earth dams have a porous, multiphase, and complex medium, and the hydraulic and mechanical variables in different parts are associated with uncertainty. For this reason, in recent years, the regulations for the design of dams have been reforming in the direction of applying non-deterministic and probabilistic variables in the calculations. A probabilistic engineering view leads to a more realistic understanding of design than deterministic approaches. In the research, artificial intelligence (AI) methods have been used to analyze the data, which provides a predictive model of behavior for seepage discharge flow through the earth dam. In general, the present research has two purposes a) to estimate the effect of uncertainty of the hydraulic conductivity dam on seepage discharge and b) to provide a model to estimate seepage discharge in a dimensionless way with the gene expression programming (GEP) and support vector machine (SVM) methods.

Monte Carlo simulation (MCS) with 2000 iterations was executed for stochastic analysis. The first step of the Monte Carlo simulation is the choice of the deterministic performance function. In the second step, the input variables were defined to the performance function and the probability distribution for variable/variables. By repeating the process n times, n random answers were extracted for the resulting problem, and finally, probability density function (PDF) and cumulative density function (CDF) graphs were drawn for the results. In the Fortran code of this research and to check the convergence, the hydraulic heads were compared to achieve the difference obtained in iteration n with the obtained value in iteration n-1, and if the difference is less than the tolerance error, then the program stops. In the next section of the algorithm, the obtained data (from the repeated execution of the MCS) are converted into a model for a description relationship between the effective seepage discharge (ESD) and the input variables by using the metaheuristic methods that include; gene expression programming (GEP) and support vector machine (SVM). After GEP and support vector regression (SVR) modeling the predicted and observed results were compared by statistical indexes such as MSE, RMSE, MAE, and Correlation coefficients.

The different models of earth dams were implemented in the Fortran program, and the average and standard deviation of the seepage discharge flow in the uncertainty state were obtained. To determine the relationship between the ESD value, indicators had been defined that these parameters used for the Gene Expression Programming model include; Kx/Ky, W/B, Bd/B, Bu/B, Hdam/B, Hu/Hdam, and Hd/Hu. These were the factors influencing the seepage discharge of the earth dam, and the discharge component is also defined as the effective seepage discharge (ESD) in a dimensionless manner. Kx and Ky are soil permeability in the direction of the horizontal and vertical axes respectively (m/s), W is the width of the crest, B is the width of the base of the earth dam, Bd is the horizontal distance of the dam tip from the downstream side from the crest, Bu is the horizontal distance of the dam tip from the upstream side crest, Hdam height of the dam, Hu height of the reservoir level, Hd water height downstream of the dam, all the variables are in meters. By increasing the Kx/Ky ratio of horizontal to vertical hydraulic conductivity by 49%, the Effective Seepage Discharge increases by 14%. If the horizontal variable of permeability is increased by 25%, the ESD rate increases by 4.56%, similarly, if the vertical variable is increased by 25%, the ESD decreases by 4.72%.

After finite element analysis, and modeling with two methods of gene expression programming (GEP) and support vector regression (SVR), the statistical analysis of the methods showed that the two calculation models had a good prediction of the ESD with a correlation coefficient above 0.9. Vertical hydraulic conductivity (Ky) has a greater effect on the ESD rate than horizontal hydraulic conductivity (Kx). The results of the geometric investigation of the dam also show that the increase in the ratio Hdam/B has a direct impact on the ESD and also the lower the slope downstream of the dam leads to the lower the ESD. The statistical analysis was used to compare the results of the data obtained from Fortran output for SVR and GEP models. In general, the SVR model is closer to the model resulting from the Fortran code rather than the GEP model, and it has a low root mean square error (RMSE) and a high correlation coefficient.

In the analysis of saturated and semi-saturated soil media, the use of the finite element method results in more realistic analyses than deterministic methods due to the random nature of porous media properties. The purpose of this research is to investigate the impact of uncertainty in the prediction of seepage flow through earth dams using the Fuzzy Monte Carlo Simulation (FMCS) new hybrid algorithm, which is implemented with the help of the finite element method and monte carlo simulation. In this study, a computer program was used for Finite Element Analysis (FEA), which was definitively checked after validation with experimental results. Monte Carlo iteration loops were then used for probabilistic mode. The Fuzzy Finite Element Method (FFEM) was executed assuming the probability of the soil for four variables: soil permeability (Kx/Ky), water height ratio (Hd/Hu), horizontal width of downstream slope ratio to base width (Bd/B), and horizontal width of downstream slope ratio to horizontal upstream width (Bd/Bu). The results of this research show that the fuzzy membership function is linear-symmetric for Kx/Ky variables and linear-asymmetric for two geometric variables, Bd/B and Bd/Bu. Additionally, the membership function was extracted for Hd/Hu.

Gibson et al. (2010) modeled the COWLITZ river considering the moving bed and used the HEC-RAS model for simulation. They did the modeling for the last 20 miles of the river because the possibility of flooding due to sedimentation was higher in this area. The purpose of this study was to evaluate the effects of sedimentation on the increase of flood risk in the long term. The Laursen-Copeland relationship was used in the sediment calculations because the sediments ranged from very fine sand to large rubble. They also stated that the ability to add bed particle size in 20 different classes has been added to the HEC-RAS model in version 4.1. The geographic location of this research is based on the UTM geographic system, around 33'22'32' to 32'45'17 north latitude and 40'22'48' to 48'57'19 east longitude. According to Figure 1, the total length of the studied route is about 75 km between Zargan and Farsiat and includes 155 cross sections, and the approximate length of the meander is 13.4 km. In order to simulate the hydraulic flow and sedimentation of the river by HEC-RAS model, geometric information (cross sections, distance of sections from the downstream control section, Manning's roughness coefficient and opening and narrowing coefficients), hydraulic information (flow information and water level level at the lower station) meteorological (water temperature) and sedimentary (related to flow-sediment discharge and bed sediments granularity) is necessary. In general, it can be said that after the formation of the loop, the upstream interval (R1) of its sedimentation decreases from upstream to downstream until it undergoes erosion at the bifurcation of the river, and the middle interval (R2) changes from erodible to sedimentary and the interval Downstream of the ring (R3) remains almost unchanged and shows very little tendency to erode. HEC-RAS model is used in this research. When using this software, the continuous flow series is divided into continuous flow segments based on flow and time variables. In general, it can be said that after creating the ring of the upstream interval (R1), its sedimentation decreases from upstream to downstream until it undergoes erosion at the bifurcation of the river, and the middle interval (R2) turns from erodible to sedimentary and the base ring interval (R3) remains almost unchanged and has a very little tendency to be erodible. The middle section of the Karun River (R2) turns from erodible to sedimentary with the creation of a loop, which is the reason for the tendency of the river to deposit sediments in this section after the creation of the loop, reducing the amount of incoming flow and, as a result, reducing the speed The flow in this section is caused by the division of the flow due to the two branches of the river upstream of this section.

In general, earth dams are subjected to both static and dynamic loads, such as earthquakes. Previous research has focused on dam seepage modeling without considering the effects of dynamic loads on the porous medium. To address this issue, a code was developed using the FORTRAN programming language to solve the coupled u-p equations for the Downstream San Fernando dam (DSFD). The dynamic force variables, including frequency (f), amplitude (A), and Arias intensity coefficient (AI), were considered fuzzy variables. Additionally, the Buttress-Hatami (BH) model was utilized for loading, where the Arias intensity factor (AI) was used to express the dynamic energy in the structure. The results indicate that in the dynamic-fuzzy model, an increase in the AI coefficient from 0.1 to 1 in the Batras-Hatami model leads to a 2.8-fold increase in the range of flow changes in the dam foundation. Furthermore, in the range of 12.1-16.5 Hz, with an increase in frequency (f), the values of peak flow rate (PSD) in both the foundation and body parts are closer to their value in the static state.

The purpose of the present research is to investigate the damage analysis mechanisms of the Dam-Reservoir-Foundation system using the Finite Element Method (FEM). The study focuses on the Koyna dam-reservoir-foundation system, which is a two-dimensional model that has been subjected to the horizontal and vertical components of ground acceleration in the Koyna earthquake using ABAQUS software and the Concrete Damage Plasticity (CDP) model. The comparison of models in linear and linear analysis shows that considering the bottom of the foundation for applying the load increases the seismic damage compared to applying the bottom of the dam. The results indicate that applying foundation excitation at the contact surface of the dam-foundation in the condition of foundation without mass, as well as applying foundation excitation at the level of the rock foundation in the condition of massed foundation can lead to a more accurate prediction of the response of the structure during an earthquake. However, the level of seismic damage in the dam is greatly affected by how the base excitation is applied and the mechanism of the modeling Dam-Reservoir-Foundation system. Therefore, it is crucial to consider the correct application of base excitation and the modeling mechanism while analyzing the damage analysis of the Dam-Reservoir-Foundation system.

Nowadays, numerical modeling is known as a powerful method and tool in investigating practical phenomena. So that this method is used in many fields of engineering. Although the numerical model of an engineering problem is usually prepared based on several simplifying assumptions, it is possible that this numerical model does not reflect all aspects of the real problem and is not able to show the real behavior in reality. Direct updating methods use the analytical solution of the problem for this purpose, although these methods specify the necessary corrections without the need to repeat calculations and in one step, but in most cases such corrections do not have a physical meaning in reality but iteration-based updating methods require sensitivity analysis of the effective parameters in the problem in order to find the impact of each of them. One of the solutions to deal with the time-consuming problem of multiple re-analyses in numerical models prepared by commercial software during model updating based on sensitivity analysis is to replace the numerical model with an approximate representative model known as meta-models. The response surface method is one of the common methods for building such meta-models. The response surface technique is actually a test design method to select the design parameters in the experiment with the aim of optimizing some system response functions. From this point of view, the research regarding the response of the network of open channels to the arrival of the flood wave and predicting the characteristics of the flow in the branches of the network can be the solution to minimize the damages caused by it.

In this research, in order to update the numerical model of unsteady flow in the network of open channels by using the combined method of response surface and meta-exploration methods, a branch of the Garmabadr River (Ziquon) has been selected, and the desired data has been prepared and sorted. have been Hec-Ras software has been used as a numerical method. Neural network is also chosen for simulating the numerical method so that the desired parameters can be optimized in the process of using the genetic algorithm method. This area is located in the northern part of Iran and in the northeast of Tehran province. The geographical coordinates include longitude 51 degrees 32 minutes to 51 degrees 38 minutes and latitude 35 degrees 51 minutes to 35 degrees 58 minutes. MATLAB software has been used to build a meta-model or an alternative model. MATLAB is a software that can be called the language of mathematics and modern engineering sciences.

As it is clear from the results of the Hec-Ras program, the discharge of stations number 13 and 22 is equal to 308.03 and 27.89 cubic meters per second, respectively. The estimation error is equal to the difference between the estimated flow rate and the observed flow rate, which is 18.03 and 2.11 cubic meters per second, respectively. The percentage of the estimation error is equal to the ratio of the estimation error to the observed value is equal to 6.2% and 7%, respectively, which is an acceptable value for this research, and this result shows the appropriate performance of the genetic algorithm for optimizing the flow simulated by It shows the neural network, on the other hand, the low percentage of error also determines the accuracy of the intended program. As a result, the error of the genetic program is at an optimal level. As it is known, Manning's coefficients are very important and influential parameters in the behavior of the flow, the change in which causes significant changes in the simulation results. The effect of this uncertainty on the performance of numerical methods was clearly identified in this research. As a result, examining inputs that have inherent uncertainty and determining their appropriate values is a suitable solution for improving numerical methods.

 Genetic algorithm is a powerful method to determine the values of effective parameters in simulated flow performance, and its combination with neural network is a powerful tool for engineering purposes, including the analysis of the behavior of open channels, whose fast convergence is a strong point to choose in these problems. in similar cases.
 Manning's coefficients are very important and influential parameters in the simulated flow behavior, with a small change in it, the simulated model undergoes significant dispersion, which should be considered in the analysis process so that the results are not significantly different from reality.
 Optimizing an effective parameter in simulated flow behavior is an erosive and time-consuming process, and the use of neural network becomes much faster and more reliable due to the high convergence speed of this process.

Agriculture has played a vital role in the economy, life, and culture in the civil history of Iranians. In recent years, this sector is the largest consumer of freshwater resources in this country. One of the adaptive ways to deal with the water shortage is the optimal use of water (Emami et al, 2020). In the production process of a commodity, different sources of water may be used, and the type of water supply source can play a significant role in the analysis of virtual water trade (Mircholi et al, 2016). In the period of 2016-2018, previous research covered by the Moghan irrigation network has been conducted in the field of physical and economic water productivity indicators estimation of crops. Also, in previous studies, only Benefit Per Drop (BPD) and Net Benefit Per Drop (NBPD) indices have been used to estimate the economic productivity of agricultural water. Therefore, in this research, the agricultural year 2020-2021 was studied in order to investigate the physical and economical water productivity indicators of crops covered by the Moghan irrigation network.

The Moghan plain is located in the northwestern part of Iran, on the west side of the Caspian Sea, and north of Ardabil province, on the border between Iran and the Republic of Azerbaijan. The total area of the Moghan watershed is more than 5545 square kilometers (Sookhtanlou, 2019). The altitude of the region is 50 to 600 meters above sea level and its climate is semi-arid and moderate (Azizizohan et al, 2021). Most of the agricultural farm covered by Moghan's irrigation and drainage network is devoted to cultivating crops such as wheat, barley, seed corn, fodder corn, soybean, rapeseed, rice, tomato, cotton, sugar beet, and peanut. In this research, these products' virtual water content and physical and economic water productivity are investigated.
In this research, in order to complete the previous studies in the aforementioned field, the virtual water content of the studied products has also been investigated. In addition to the BPD and NBPD index, the Unit Virtual Water Value (UWV) index has been studied to further investigate the Moghan irrigation network economic efficiency of water crops.

The content of gray virtual water, blue virtual water, green virtual water, and white virtual water of the studied crops, sugar beet, tomato, and fodder corn, have the lowest content of gray virtual water among crops. Among the studied crops, fodder corn, tomato, and sugar beet products, respectively, have the highest physical water productivity, and rice, soybean, cotton, and peanut respectively have the lowest physical water productivity. The amount of physical water productivity calculated in this research for all the jointly studied crops except tomato, canola, and seed corn is lower than the amount of physical water productivity estimated by Farahza et al (2020).Regarding gross value index per unit of irrigation volume among the studied crops tomatoes, peanuts, fodder corn, barley, and wheat, respectively have the; highest, moreover peanut, tomato, cotton, fodder corn, and sugar beet products, respectively, have the highest net value index per unit of irrigation volume among the studied crops, however, barley, wheat, rice, and grain corn, respectively, have the lowest net value index per unit of irrigation volume among the studied crops. In addition, tomatoes, peanuts, fodder corn, wheat, and barley have the highest index of value per virtual water unit among the studied crops, respectively, while rice has the lowest value index per virtual water unit among the studied crops.According to the BPD index, tomatoes, peanuts, fodder corn, barley, and wheat are the first to fifth priorities for cultivation in the Moghan Plain. The first to fifth priorities for cultivation in the Moghan plain according to the NBPD index are peanuts, tomatoes, cotton, fodder corn, and sugar beet, and based on the UWV index, tomatoes, peanuts, fodder corn, wheat, and barley are the first to fifth priorities.

In the current research, the content of virtual water and the amount of physical and economic water productivity of crops covered by the Moghan irrigation network were calculated. The most important results of this research are presented below.The Crop Per Drop (CPD) index of rice shows the last level in the crop year 2019-2019 due to the amount of water consumed and significant cost. Also, in the analysis of BPD and NBPD index, this product has the lowest and ninth priority, respectively, and in the current water shortage conditions in the Moghan plain, there is a need to review the cultivation of this product. Tomatoes and fodder corn have good productivity in all three indices of CPD, BPD and NBPD in the crop year of 1399-1400. In fact, while tomato does not have a low water requirement, measuring the performance of this product shows the high net and gross profit obtained according to the cost of planting and harvesting.The amount of UWV index of wheat, rapeseed, soybean, rice, fodder corn, seed corn, tomato, barley, sugar beet, cotton, and peanut products is 24269, 15644, 18894, 9956, 36279, 17362, 50073, 23010, 21748, 19403 and 45718 rials per cubic meter, respectively. The proposed approaches and models of this research are different depending on whether the index of physical productivity or economic productivity of water is considered in planning and policy-making.

Side weirs are types of hydraulic structures, which are used for different purposes in water transmission systems. In most of the construction operations of irrigation channels and water transfer, based on the topographic conditions of the land, the bottom of the channels is sloped. The purpose of this research is to numerically investigate the changes in the slope of the bottom bed and evaluate the performance of the side weirs in flood conditions and supercritical and subcritical flow regimes. To simulate the flow, CFD method and FLOW-3D® software and RNG turbulence model were used. By examining the surface profile of the flow passing through the weirs at different bed slopes, it was observed that in a fixed slope, in the subcritical flow regime, the surface profile trend is increasing from the beginning to the end of the weir, and decreasing in the supercritical flow regime. As the slope of the main channel bed increases, the level of flow passing over the weir decreases. On average, by changing the regime from subcritical to supercritical, the weir efficiency decreased by 11.21%. Increasing the bed slope decreased the weir efficiency and discharge coefficient in the subcritical flow regime up to 14.54% and in the supercritical flow regime up to 9.26%. The increase in discharge coefficient with the increase of the weir height varied between 4.6 and 7.8 percent. With the increase of the slope of the channel bed, the velocity along the weir in the subcritical and supercritical flow regimes increased by 10.88 and 6.17%, respectively, and the transverse velocity decreased by 22.23 and 4.8 percent, respectively for the subcritical and supercritical flow regimes.

In the present study, the evaluation of hydraulic performance and operation of water flow measuring structures in the Moghan irrigation network has been reviewed and presented. In the Moghan irrigation network, 1246 intake gates have been installed to control and regulate the water level, except for the inlet gates at the dam site, Sluice gates have been used as flow measuring structures. Like other irrigation networks in the country, this network is facing the problem of imprecise flow measuring structures. For this reason, in the implementation of network improvement, about half of the structures were replaced with Neyrpic-Modules. In this research, by visiting the network and reviewing the available maps and information, four canals of the network were randomly selected, in each of the canals, water flow measurement tests and necessary surveys were performed on the structures. To measure the desired location, the actual discharge rate was measured at different discharge rates and in at least three replications by an ultrasonic flowmeter. In each structure, the actual discharge rate was compared with the nominal discharge rate of the structure used in its operation, and the relative error of the structures was obtained. The results of this study show that the average relative error of actual discharge and nominal discharge was between 7.11 to 34.38%. In the field of operation evaluation, improper sealing, destruction, and inefficiency of water level determination gates and opening of gates, decay, and manipulation of gates were some of the problems of operation of structures.

Seepage through the soil is one of the most important issues of Fluid-Structure Interaction (FSI) that can lead to liquefaction, boiling of sand in downstream, settlement of hydraulic structures, instability and failure of embankments and earth dams. Accurate calculation of the amount of leakage passing through the earthen dam is an important factor in ensuring its safety and stability. On the other hand, the results of seepage analysis in calculating the dimensions of drainage and filters of the dam deformation is very important (Kalateh and Afshari, 2018; Jafarzadeh and Asadnia, 2005).

To deterministic solving of the Laplace equation in soil medium is performed by Smith and Griffiths (2004), FORTRAN programming code is written that calculates the flow rate and piezometric head in the body of a homogeneous and non-homogeneous earth dam. The FORTRAN code for solving seepage equations is similar to the code for solid mechanics equations. In this code, inspired by solving the equations of static and dynamic equilibrium in solid mechanics and using the finite element method, the differential equation of seepage is solved with the difference that instead of displacement and force components in mechanical problems of seepage and pizometric head is used. In the present paper, a program based on the finite element method in FORTRAN programming language has been developed by the author that solves the Laplace equations to determine the leakage discharge of an earth dam assuming the uncertainty of the components involved. In fact, in the previous code related to seepage, soil permeability has been considered definitively, which in this study is probabilistically investigated. First, the FORTRAN code is assumed that the permeability values of the materials are constant, and the results are expressed as two leakage currents, input and output, in which case these two values are equivalent. The results show that in the isotropic state where the permeability is equal in the vertical and horizontal directions, the slope of the line is greater than the two non-isotropic states. As mentioned for deterministic modeling, the permeability of dam materials is constant in this case and is solved analytically by the Seep_4 subroutine, but in the probabilistic model and the Monte Carlo method, instead of the stability of the conductivity coefficient, the mean and standard deviation are entered in the calculations.

Figure 1 shows the relationship between the average seepage resulting from Monte Carlo Simulation for downstream reservoir ratios of 0.087, 0.136 and 0.19, which shows a graph in the range of 0.71<Kx/Ky<1 inequality slope. It has an ascending interval of 1<Kx/Ky<1.41 To be more precise, the slope of the descending section in the definite position for downstream ratios to the reservoir is 0.087, 0.136 and 0.19, respectively, equal to 0.96, 0.96 and 0.48 in the descending position and 0.73. 0, 0.88 and 1.032 are in the ascending state, with no significant difference. But in probabilistic mode for downstream ratios to reservoir 0.087, 0.136 and 0.19 with 0.41, 0.48 and 0.069 in descending mode and 0.78, 0.91 and 1.032 respectively is in the ascending state, in which the slope of the ascending part is at least one and a half times greater in all three states. It is worth mentioning that in all three cases and in both intervals, the coefficient of explanation of the linear relationship is above 0.98, which was calculated by SPSS software and linear regression method. Fig 1-a- Average seepage flow of earthen dam for changes in horizontal to vertical permeability ratio (Kx/Ky) in deterministic analysis. 1-b- The amount of flow through the Earth dam in change for changes in the ratio of horizontal to vertical permeability (Kx/Ky) in probabilistic analysis.

In the deterministic analysis, the effect of horizontal permeability on the seepage flow rate not show a significant difference compared to the effect of vertical permeability, but in probabilistic analysis, the effect of horizontal permeability on average of seepage flow rate is at least 89% higher than vertical permeability. • The results of probabilistic leakage study show that with increasing the ratio of downstream to upstream, the range of discharge in the frequency distribution function (PDF) and the average leakage discharge decreases. • With decreasing the width of the earthen dam crown, the average seepage flow decreases and with the upward movement of the dam crown, this amount increases. • In all cases, the average seepage flow calculated in different cases of Monte Carlo Simulation (MCS) models is 16 to 270% less than the seepage flow in the definite case.

Unpredictable settlement of earth dams has led researchers to develop new methods such as artificial neural networks, wavelet theory, fuzzy logic, and a combination of them. These methods do not require time-consuming analyses for estimation. In this research, the amount of settlement in rockfill dams with a central core has been estimated using artificial intelligence methods. The data of 35 rockfill dams with a central core were used to train and validate the models. The artificial neural network, wavelet transform model, and fuzzy-neural adaptive inference system are the proposed models which were used in the present study. According to the results, the best model for an artificial neural network had two hidden layers, the first layer of 18 neurons and the second layer of 7 neurons, with the Tansig-Tansig activation function, with a coefficient of determination R2=0.4969. The best model for the fuzzy-neural inference system had the ring function (Dsigmoid) as a membership function, with three membership functions and 142 repetitions with a coefficient of determination R2=0.2860. Also, combining wavelet-neural network conversion with the coif2 wavelet function due to the more adaptation this function has to the input variables, the better the performance, and this function, with a coefficient of determination R2=0.9447, had the highest accuracy compared to other models.

The main goal of preset research is investigate the effects of vertical component of Near-Fault and Far-Field earthquake records on the probability of overtopping induced damage of earth dam due to the reduction of freeboard due to the settlement of dam crest. In this respect 12 different earthquake record are selected. Nonlinear dynamic analysis of earth dam is implemented with FLAC 3D using Finn model that relates the increment of volume decrease per cycle of shear strain to the cyclic shear strain amplitude for considering the pore pressure build-up during seismic loading. Obtained results show that the response of dam for near-fault earthquakes considerably is larger than far-field records. Applying vertical component of earthquakes in the dynamic analysis caused the horizontal maximum displacement of damchr  crest increase 5.58% for near-fault records and 2.96 % for far-field records and also maximum settlement for damchr crest increase 31.69 % for near-fault records and 73.65 % for far-field records with including vertical component of records in the dynamic analysis, Also can be get form obtained results the damage probability of dam with considering vertical component of earthquakes is increase 249% for near-fault records and increase 2419% for far-field records.

The stability of a gravity dam on a jointed rock foundation might be endangered by weak joints that may be present in the fracture network of the bed rock. A review of the literature shows that there are few studies of the effect of a weak joint in the foundation rock on the stability of dams. This research uses the finite difference numerical modelling software ABAQUS to model a gravity dam, the foundation rock, and the influence of a weak joint (using interfaces), that exist in the bottom of dam with different direction, on the stability of the dam. To do this, a conceptual model has been developed and one representative joint of a discrete fracture network with seven different dip angle was examined. Thses different varying dip angles were studied in order to investigate the critical configuration that has the most significant effect on the dam’s stability.As a case study, Pine Flate dam, is modeled with the ABAQUS software as a two-dimensional and Nonlinear dynamic analysis is done by implicit method with applying vertical and horizontal components of the El-Centro earthquake. The obtained results show that existness of joint in the foundation significantly affected the dynamic responcse of dam.

In last decades with an increase in the number of terrorist attacks and other unintentional explosions, the study of blast loading and response of infrastructures have gained much importance. Elevated liquid storage tanks are one of the major infrastructures that play important role in industries. Liquid storage structures can use for the storage of water, milk, liquid petroleum and chemicals in industries. Blast loading on liquid storage structures may lead to disaster due to water crisis. Hence, understanding the dynamic behavior of liquid storage structures under blast loading through numerical simulations is of utmost importance. In the present study, three dimensional (3D) finite element (FE) simulations of a steel water storage elevated tank with annular baffle that put in the specific height of tank’ s wall subjected to blast loading is investigated using the FE software ABAQUS. The coupled Euler–Lagrange (CEL) formulation in ABAQUS has been adopted herein which has the advantage of considering the coupling of structural mechanics and fluid mechanics fundamental equations. Three different aspect ratio (H/R) are considered in the present study and two different water levels, i.e., full tank and half full tank are considered. Obtained results show that baffle reduces overturning moments and sloshing in both cases of full and half full tanks.

Sediment in the dam’s reservoir has a significant role on mitigation of dynamic response of concrete gravity dams and also the seismic response of dams in near-field motion can be considerably different from those observed in the far field and the near-fault ground motions can cause considerable damage during an earthquake. This paper presents results of a study aimed at evaluating the sediment effects in the near-fault and far-fault ground motions on nonlinear dynamic response and seismic damage of concrete gravity dams including dam-reservoir-foundation interaction. For this purpose, 3 as-recorded earthquake records which display ground motions with an apparent velocity pulse are selected to represent the near-fault ground motion characteristics. The Shafaroud gravity dam, which is selected as a numerical application, is subjected to a set of as-recorded near-fault and far-fault strong ground motion records and three different level of sediment are assumed. Results show that in the near-fault horizontal earthquake with assuming 2 m sediment height a 3.67% reduction and with 8 m sediment height a 10.33% reduction in dam crest displacement are obtained but in far-fault ground motion reservoir sediment do not have a sable pattern effect on dam’s response. Therefore, any dam must be evaluated for sediment effects on its dynamic response individually.

Biot equations that consider fluid and soil interaction at the same time are the most applicable relationships in the soil dynamic analysis. However, in dynamic analysis, due to the sudden increase in the excess pore pressure caused by seismic excitation and the occurrence of high hydraulic gradients, the assumption of the Darcy flow used in these equations is questionable. In the present study, in the u-p form of Biot equations, non-Darcy flow is considered. Also, the nonlinear behavior of soil is modeled by the Pastor-Zienkiewicz -Chan model. For validation, the VELACS No.1 experiment is modeled and the effect of the nonlinear fluid flow assumption on the results is examined. The results indicate that in the low permeability coefficients, the obtained results of the non-Darcy and Darcy flow are in agreement; however, in high permeability coefficients, these two methods differ by time and depth.

Uplift force has significant role on dynamic response of concrete gravity dams and also seismic response of dams in near field motion can be considerably different from those observed in the far field and the near –fault ground motions can cause considerable damage during an earthquake. This paper presents results of study aimed at evaluating the uplift force effects in the near-fault and far-fault ground motions on nonlinear dynamic response and seismic damage of concrete gravity dams including dam-reservoir-foundation interaction. For this purpose, 3 as-recorded earthquake records which display ground motions with an apparent velocity pulse are selected to represent the near-fault ground motion characteristics. The Shafaroud gravity dam, which is selected as a numerical application, is subjected to a set of as-recorded near-fault and far-fault strong ground motion records and three different distribution of uplift force are assumed. The results obtained from the analysis of the dam subjected to each fault effect are compared with each other. It is seen from the analysis results that the uplift force, which has influence on the dynamic response of concrete gravity dam-reservoir-foundation systems subjected to near-fault ground motion, as has the potential to increase damage in the dam body but at far-fault motion uplift force can be neglected.

The present study investigate the effects of mechanical properties of the rock layers in the foundation of concrete gravity dam on the seismic response of gravity dam–reservoir –foundation systems. The mutual effects of different domains are considered in the present research. As a case study the biggest section of Shafarud dam in the north of Iran is modeled two dimensionally using ABAQUS software and its response to the may 1940 El–Centro California earthquake is considered.Four different ratio of elasticity modulus of foundation to the elasticity modulus of concrete of dam body are applied in the analysis obtained results show a significant effect of the foundation material properties on the crest displacement of dam and stress distribution in the dam bodywhich highlight the importance of detailed survey in order to identify the features of the site before construction.

In this study, reservoir water level effects on nonlinear dynamic response of concrete gravity dams are investigated. For this purpose, the nonlinear behavior of the dam concrete is captured using the concrete damage plasticity (CDP) on the non associated flow rule assumption. Water in the reservoir is represented by the Lagrangian (displacement-based) fluid finite elements. The program ABAQUS is applied for nonlinear dynamic analysis of dam-foundation-reservoir systems and employed in the response calculations. Nonlinear dynamic analysis of Shafarood concrete gravity dam subjected to three far-fault and three near-fault earthquake groundmotions are performed for three different water levels. The crest displacements, the failure element distribution in dam body and damaged Index in different conditions are presented. The results obtained from nonlinear analyses for different water levels are compared with each other. It is apparent that the reservoir water level significantly affected the dynamic response of gravity dam but under near-fault ground motions reservoir has a mitigation effecton nonlinear dynamic response of dam.

Dynamic response of dams interacting both with reservoir and foundation is a complex problem in time domain. To study the effects of reservoir and foundation on the response of dams under two-dimensional (2D) conditions, several numerical methods have been developed in the past few decades such as finite element method and the boundary element method. The boundary element method has been successfully applied to the dam dynamics (Humar and Jablonski (1988); Kucukarslan, (2004))

A significant increase in pore water pressure during construction of earth dams may lead to the hydraulic fracture of dam body in pounding. Thus having sufficient information about generation pattern of excess pore water pressure inside the core is essential. In the present study, using finite element method in coupled analysis of earth dams, excess pore water pressure and displacement values are estimated during the construction of Daroongar dam by developed Fortran code, and the results were compared with instrumentation data. Finally the actual amounts of horizontal and vertical permeability coefficients were determined for the materials by regression analysis.

In the present paper a new numerical simulation method based on finite volume is developed for calculating hydrodynamic pressure distribution in the reservoir of dams during earthquake excitation. An explicit finite volume scheme is applied for discretization of dynamic governs equation. In the proposed method the asymmetry effect of reservoir shape on hydrodynamic pressure distribution can be considered. In the simulation quadrilateral elements with center cell algorithm is used. Because of the negligible changing of hydrodynamic pressure in the cross direction with averaging, the average differential partial equation in central vertical plan of reservoir is solved. The absorption effects of bottom sediment and lateral wall are included in the analysis and an exact far end boundary condition is applied in the truncation boundary. Different approaches to the solution of the coupled field problems exist solution of the entire set of equations as one discretized system, referred to as the monolithic approach. This approach is often inefficient due to its attempt to capture with one discretization methodology the completely different spatial and temporal characteristics of fluid and the structure. The second approach often mentioned is the notion of strong coupling, referring to solvers which might use different discretizations for the fluid and the structure but which employ sub-iteration in each time step to enforce coupling between the fluid and the structure. In these methods, the governing equations for fluid and structure are discretized separately in each of the sub-domains and coupled using a synchronization procedure both in time and in space without sub-iteration. Weakly –coupled schemes have been extensively applied to a variety of different fluid-structure interaction problems of engineering interest in past ten years. wo vital issues when coupling two domains are: the method of data transformation between domains and what information must be transferred. The property of fluid adjacent of a structure such as density and viscosity are also key parameters in the efficiency of a numerical scheme.A dense fluid coupled with a structure cause a strong coupling and required some special technique to overcome corresponding difficulties. Key questions with this approach include properly enforcing boundary conditions at the solid-fluid interface, and accurately transmitting tractions between the solid and fluid. The biggest complaint about the explicit staggered partitioned solution procedure is the typical instability associated with the method,that is generally caused by the time lag between the integration of the fluid and structure equations. In the typical partitioned method, the fluid and the structure equations are integrated in time, and the interface conditions are enforced asynchronously. In the solution of coupled problems using partitioned methods, it is necessary to find a cost-minimization (optimization) compromise between a few passes solution with small time steps and a more iterated solution with larger time steps. This compromise may depend, among other things, in the degree of nonlinearity of the structural problem, which may require equilibrium iterations independently of the interaction effects. From the computational point of view, a one–pass solution with no iteration would be optimal, but stability consideration may prove this impractical.

Dams are one of the most important structures which are built to prepare water for different usages such as drinking, agriculture, industrial, flood control and hydro power generation. Due to the importance of dams and increasing number of terrorist attack, Stability of dam structures against blast loading is important. Dam responses depend on magnitude of released energy and if the dam structure could not be able to resist and maintain its stability against this energy, irreparable consequences will happen. Explosion is a sudden release of energy which could be like gases combustion, nuclear explosion or any kind of bombs. TNT unit usually used as reference to determine the explosion power. Some of basic properties of an explosion are random location of explosion, transient loading and short time loading (up to few seconds). When blast loading happened, energy will released suddenly and this released energy include thermal radiation and wave scattering in air and earth. The waves which scattered in the air are the main factor to structural damage. These waves move faster than sound wave velocity and impact the structure. Due to reflex from structure surface, the pressure of these waves increased and also some air waves penetrate to structural elements from openings such as doors and windows. This process continues until all available parts of the structure affected by pressure waves. In this research, the effects of blast loading on Karun 4 dam are investigated. To this purpose, dynamic analysis of dam-reservoir-foundation system is performed by finite element model using ABAQUS software. Dam-reservoir-foundation modeled three dimensional in which reservoir length is three times greater than dam height. The foundation modeled as a hemi-sphere with a radius of three times greater than dam height. Non-linear material behavior also considered by using concrete damage plasticity method. The CONWEP theory is used to model blast loading. To verify the blast modeling theory and software abilities, a steel plate which investigated under blast loading in references has been modeled and the results shows same responses with the paper. The responses of dam are investigated under two different reservoir conditions include full and empty conditions. Analysis also done for three different explosion points in three different elevations. Explosion points are near base, mid height of dam and near dam crest respectively. All these points have 10 m distance from dam structure. TNT mass used in each noticed conditions, is the minimum amount of TNT which cause damage in dam body. The results indicate that the responses of the dam is very sensitive to mesh dimensions. The results also show, water level has not great effect on explosive mass which is needed for structural damage of the dam. In both full and empty reservoir conditions, when explosion happened near the dam crest, the displacement is more than other cases. It is noteworthy that when the explosion happened near the crest, the maximum displacement of the crest and the point in front of the explosion point, occur in same time but when the explosion point is in middle and also near the base, theses displacements are not in same time.