Hossein Bahrami; Soroush Farkhondeh; Javad Ahadiyan
Abstract
Civil construction work in coastal areas and problems caused by undesirable soils of these areas in some places has made geotechnical studies essential for the identification and improvement of these substrates. One of the important points in the improvement of soils in all construction projects is the ...
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Civil construction work in coastal areas and problems caused by undesirable soils of these areas in some places has made geotechnical studies essential for the identification and improvement of these substrates. One of the important points in the improvement of soils in all construction projects is the choice of the type and amount of material used in the mixing plan with the soil. This choice is usually based on Requirements for a development activity and practical experience. In this study, firstly, experiments were carried out on the seawater sand mix with cement, clay and nanoclay and soil characteristics such as optimum density and humidity, modulus of elasticity, cohesion and internal friction angle were investigated. Then, using plaxis software modeling, the final displacement, strain, and final ultimate stress were compared. The results of the software investigation revealed that the mixing design of the nano-cement and sandy soil is efficient. The total displacement in cement and nanoclay combination with sandy soil decreased from 1.86 to 0.858 mm. Also, the final strain rate decreased from 55.6 to 11.06% in the combination of cement and nanoclay with sandy soil. The increase in final stress was also observed from 111.47 to 130.71 kpa in the combination of nano and cement.
مهندسی دریا
hossein bahrami; Mehdi Ghomshi; Seyed Mahmoud kashefi por; Seyed Ali Akbar Salehi Neyshabouri
Abstract
It is well known that the shortage of water is one of the most serious problems that faces the mankind. Therefore the study and search for the phenomenon that have impact on the water reservoirs and other natural resources of water, is essential. One of the most fundamental phenomenons relating to water ...
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It is well known that the shortage of water is one of the most serious problems that faces the mankind. Therefore the study and search for the phenomenon that have impact on the water reservoirs and other natural resources of water, is essential. One of the most fundamental phenomenons relating to water reservoirs is the density currents. The importance of the investigation and analysis of the hydraulic behavior of density currents will be apparent when we consider the consequences of the occurrence of these currents and its effects on the erosion of water reservoirs and also the sediments that they cause to be deposited in these reservoirs. For example the incoming of these currents in water reservoirs will effect the biological activities, it may cause sediments in these water reservoirs or it might press down these sediments to the bottom of water reservoirs.
مهندسی دریا
hossein bahrami; samad emamgholi zadeh
Abstract
Accurate estimation of sediment concentrations in hydraulic sediment transport from different viewpoint such as sediment discharge estimation of river, selection of hydraulic structures and etc. are important. With respect to importance of this issue in this study for prediction of sediment concentration ...
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Accurate estimation of sediment concentrations in hydraulic sediment transport from different viewpoint such as sediment discharge estimation of river, selection of hydraulic structures and etc. are important. With respect to importance of this issue in this study for prediction of sediment concentration of Karun river multi-layer perceptron artificial neural network (ANN / MLP) was used.For this purpose 125 field data including bottom concentration, flow velocity, nearest distance from the beach, and thetotal depth of flow and flow depth was used.Three statistical metrics namely mean absolute error (MAE), root mean square error (RMSE) and coefficient of determination (R2) were used to evaluate the performance of ANN model. The result shows that MLP model with one hidden layer, Sigmoid transfer function and 5 neurons have best structure in the modeling of sediment concentration of Kroon River. The R2 and RMSE value is equal to 0.953 and 63.37 mg/l in training stage and 0.752 and 203.02 mg/l in testing stage, respectively. Finally, the sensitive analysis also showed that the nearest distance from the beachand flow depth had the most and the least effect on the sediment concentration, respectively.
مهندسی دریا
hossein bahrami; Mehdi ghomeshi; Seyed Mahmoud kashefi por; Seyed Ali Akbar Salehi Neyshabouri
Abstract
Density current is one of the relative motions that occur between two fluid layers, even in fluids with small difference in density. Differences in specific mass may cause of temperature, suspended material, solved material or a combination of them. These currents are so important specially in cases ...
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Density current is one of the relative motions that occur between two fluid layers, even in fluids with small difference in density. Differences in specific mass may cause of temperature, suspended material, solved material or a combination of them. These currents are so important specially in cases such as water containing sediment entering rivers into dam reservoir, seas or lakes and can also have destructive effects such as sedimentation in reservoir and estuaries to the sea and coastal areas as well as changing bedding sets Offshore areas (Kostic & Parker, 2005). The identification of type of move and change in current regime on the characteristics of the flow movement is very important. Investigation of flow movement, require to recognition of velocity profiles. A physical modeling used for this proposes and measurement and investigation of velocity on the body of current carried out. The results showed that the Coefficients of velocity profiles in wall and jet regions were respectively 2.83, 0.87 and 2.08 for sub critical flow and 1.174, 1.062 and 2.09 for super critical flow, also the maximum height of the supercritical flow was lower than sub critical flows. The other results showed that the velocity reduced 14 to 19 percent and the flow depth increased 21 to 32 percent affected by hydraulic jump respectively. Also, in some cases, large differences were observed between the results of the analytical jump relationship and measured data.
javad ahadiyan; fariborz mohammadi; hossein bahrami
Abstract
One of the solutions for the rapid draw down influences of sewage into stagnant ambient fluids such as seas and oceans is the utilizing of submerged jets. The exploitation of submerged jets reduces the peril and risk of creating wastewater to ambient environment in the water resources. Th. This study ...
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One of the solutions for the rapid draw down influences of sewage into stagnant ambient fluids such as seas and oceans is the utilizing of submerged jets. The exploitation of submerged jets reduces the peril and risk of creating wastewater to ambient environment in the water resources. Th. This study shall focus on the impact of the vertical angle; draw down discharge and density of the flow on the distribution pattern of a single density jet. In the experiments programming, a physical model was used and a total of 27 tests were performed. The experiments were carried out on 3 vertical angles of 30°, 45° and 60° respectively, 3 discharge rates and 3 different concentration of the injected fluid. The results obtained is focused on the maximum height parammbient fluid and the jet flow injection occurs. Moreover; a direct relationship can be observed between the non-dimensional parameters of the maximum height of trajectory point and the Densymetric Frude number in all of the vertical angles. While, the slope coefficient of this variation for the angles of 30°, 45° and 60° degrees are 1.18, 1.97 and 2.33 respectively. Findings show a 72% decrease of longitudinal parameter of trajectory (Xmax/dp) due to increasing vertical angle from 30 to 60 degrees. In addition, in the lower vertical angles of jets the effect of Densymetric Frude number is increased.