جستجوی مقالات مرتبط با کلیدواژه "اجزاء محدود" در نشریات گروه "آب و خاک"

General assumption in designing cut off walls is that the seepage be held in a limited amount. In order to control the seepage, the foundation drains are located in parallel to cut off wall at downstream. The main aim of foundation drains construction is to collect seepage water and decrease uplift force. Numbers, distance, and diameters of these drains need technical judgment about characteristics of foundation stones. The depth of drains depends on cut off wall characteristics. In this study, the performance of drains in foundation of concrete gravity dam was investigated using finite element method (FEM) via Seep/w software. Among influential parameters in studying the drain effects, one might consider diameters, center to center distance, and distance of the drains from upstream of dam. In this paper effective parameters on uplift force were analyzed and it was found that increasing the drain diameter had lesser effect on decrease of the uplift force slightly compared to the other parameters. In the other words, selecting the best diameters depends on executive consideration. But decreasing the distance of drains and also their distance from upstream of dam would play an important role in decreasing the uplift force. Focusing to the simulated range of parameters, the drains with 15 centimeter diameter and distance of 3 meters had the optimum performance and the best operation in decreasing uplift force. For validation, the numerical method used in this research was compared with the other analytical methods and the proper agreement with them was observed.

Seepage in earth fill dams is one of the important factors that may cause the erosion and slope instability if it is ignored. Therefore, it is crucial to calculate the leakage discharge through the body of dam and foundation, to prevent economic and life hazards by considering technical and economical issues. In this research, the seepage analysis of the body and the stability of the upstream and downstream slopes of Golfaraj dam after construction, during steady state seepage, rapid drawdown of reservoir and OBE, MCE earthquakes have been investigated and compared by applying different limit state equilibrium methods including: Spencer, Bishop, Janbu, and Mohergenstren-Price, using built-in Geo studio software. The results showed that seepage discharge in a deep section without dike was 18.2 m3day-1 per unit width which was reduced in the case of applying a cutoff or a concrete blanket by 95 and 10 percent, respectively. Data obtained from the slope analysis indicated that the slope was stable under any circumstances and the limit equilibrium methods were convergent.

In this research, the shallow-water equations are described and the governing equations are discretized using Rayleigh–Ritz method in order to assemble the required local and global stiffness matrices. The depths and the velocities of fluid flow throughout the channel and at different times are acquired by solving the governing equations using non-explicit methods. The obtained results from the numerical model with three, five and seven node elements were compared to the pre-existing results of other researchers, and it was observed that they are in a reasonably good agreement. It was concluded that employing the non-linear elements, oscillations induced by using linear models can be efficiently reduced. Subsequently, the model was utilized to investigate Ardak dam-break as a case study. In this study, three equivalent-roughnesses (Horton, Lotter and Pawłowski) were used for the numerical simulation of the flow induced by dam-break and to calculate water depths and velocities at different times and places through the river. The maximum average-depth throughout the river was 24.78m with using Pawłowski roughness, and the maximum average-velocity was calculated 15.05m/s by using Lotter roughness at t=100s.In this research, the shallow-water equations are described and the governing equations are discretized using Rayleigh–Ritz method in order to assemble the required local and global stiffness matrices. The depths and the velocities of fluid flow throughout the channel and at different times are acquired by solving the governing equations using non-explicit methods. The obtained results from the numerical model with three, five and seven node elements were compared to the pre-existing results of other researchers, and it was observed that they are in a reasonably good agreement. It was concluded that employing the non-linear elements, oscillations induced by using linear models can be efficiently reduced. Subsequently, the model was utilized to investigate Ardak dam-break as a case study. In this study, three equivalent-roughnesses (Horton, Lotter and Pawłowski) were used for the numerical simulation of the flow induced by dam-break and to calculate water depths and velocities at different times and places through the river. The maximum average-depth throughout the river was 24.78m with using Pawłowski roughness, and the maximum average-velocity was calculated 15.05m/s by using Lotter roughness at t=100s.In this research, the shallow-water equations are described and the governing equations are discretized using Rayleigh–Ritz method in order to assemble the required local and global stiffness matrices. The depths and the velocities of fluid flow throughout the channel and at different times are acquired by solving the governing equations using non-explicit methods. The obtained results from the numerical model with three, five and seven node elements were compared to the pre-existing results of other researchers, and it was observed that they are in a reasonably good agreement. It was concluded that employing the non-linear elements, oscillations induced by using linear models can be efficiently reduced. Subsequently, the model was utilized to investigate Ardak dam-break as a case study. In this study, three equivalent-roughnesses (Horton, Lotter and Pawłowski) were used for the numerical simulation of the flow induced by dam-break and to calculate water depths and velocities at different times and places through the river. The maximum average-depth throughout the river was 24.78m with using Pawłowski roughness, and the maximum average-velocity was calculated 15.05m/s by using Lotter roughness at t=100s.In this research, the shallow-water equations are described and the governing equations are discretized using Rayleigh–Ritz method in order to assemble the required local and global stiffness matrices. The depths and the velocities of fluid flow throughout the channel and at different times are acquired by solving the governing equations using non-explicit methods. The obtained results from the numerical model with three, five and seven node elements were compared to the pre-existing results of other researchers, and it was observed that they are in a reasonably good agreement. It was concluded that employing the non-linear elements, oscillations induced by using linear models can be efficiently reduced. Subsequently, the model was utilized to investigate Ardak dam-break as a case study. In this study, three equivalent-roughnesses (Horton, Lotter and Pawłowski) were used for the numerical simulation of the flow induced by dam-break and to calculate water depths and velocities at different times and places through the river. The maximum average-depth throughout the river was 24.78m with using Pawłowski roughness, and the maximum average-velocity was calculated 15.05m/s by using Lotter roughness at t=100s.