Journal of Civil Engineering and Materials Application
Volume:2 Issue: 1, Winter 2018

In the CFRD dams, a concrete-face with a finite thickness is placed on the upstream side of the dam, which prevents water leakage from the reservoir. The construction of these dams with different heights and various specifications of materials have been welcomed a lot. Therefore, construction of CFRD is appropriate in pumped-storage reservoirs. However, due to the important role of concrete-face, the necessity of optimal studies in order to evaluate the behavior of this type of dams is obvious. In this research, the lower reservoir of Siah Bishe was studied by finite element method in order to investigate the interaction between rock-fill materials and simulated concrete-face and by an appropriate behavioral model in a three- dimensional mode that can simulate the behavior of materials in the body of the dam well. In this research, Plaxis software was used for modeling and static analysis was performed to determine deformations and stresses made in the dam and concrete slab. The elastoplastic behavioral model of Mohr-Coulomb was used to model the behavior of the materials and the technical specifications of the materials used in the body of the dam and concrete-face slab have been applied. The maximum value of settlement calculated by the software from the beginning of the constriction to filling the reservoir under the effect of gravity is 670 millimeter and the maximum settlement after phase 3 in the mode of the full reservoir in long term is 32 millimeter and the maximum horizontal displacement is 52 millimeter. Finally, the results of the settlements were compared to results of the instrumentation. The results indicate the approximation of results of the numerical modeling with results obtained from instrumentation.

The goal of this study was stability analysis of the upstream slope of earthen dams using the finite element method against sudden change in the water surface of the reservoir in the case study of Ilam Earthen dam in Ilam Province. This research was of applied type and respecting the data analysis type, the field method is used for data collection. In this research using numerical modeling by the finite element method and applying the GEOSLOPE software, attempt is made to perform stability analysis of the earthen dams to overcome existing shortcomings present in the finite element methods. The results showed that at a discharge equal to 47.7 l/s, the piezometric pressures in the body, bed and within the dam which were considered to investigate the efficiency and upstream slope of Ilam Dam, we demonstrated that the amount of upstream slope of Ilam Dam for the piezometric pressures in the body, bed and within dam were better and showed a lower compressibility. The highest exerted pressures were related to the left section at the top and bottom of dam. At discharge of 69.175 l/s we demonstrated that the amount of upstream slope of Ilam Dam for the piezometric pressures in the body, bed and within the dam was better and showed a better compressibility. The highest pressures belonged to the left section at the top and bottom of dam. At discharge of 100.55 l/s we demonstrated that the amount of upstream slope for the highest exerted pressures corresponded to the left section at the top and right section at the bottom of dam. The results of numerical analysis showed that at the time of 0.2 seconds and for the five ramps of 1, 5, 10, 20, 40 degrees, the velocity (fluctuations) in axial direction, the kinetic energy of velocity turbulence (fluctuations) at the radial and axial axes increase with increase in the ramps slope. In other words the upstream slope at a ramp of 40 degrees and time of 0.2 seconds performs better for control of the sudden changes. At the time of 0.8 seconds by increase in the ramps slope, the above mentioned characteristics are first decreased and then increased. In other words the upstream slope has a better performance for control of the sudden changes for a ramp of 40 degrees and time of 0.8 seconds. For the time of 1 second, by increase in the ramps slope the above mentioned characteristics are first decreased and then increased, in other words for the ramp of 20 degrees and time of 1 second it has better performed for control of the sudden changes.

Dam monitoring is possible by instrumentation at critical points and measurement of various parameters such as pore pressure and deformations, i.e. settlement and displacement. In this study, the monitoring of Shahr-e-Bijar Reservoir Dam is investigated using instrumentation data and numerical analysis. A finite element software package called Plaxis is used for the numerical analysis. According to the results of analyses carried out by the program that are in good agreement with observations and instrumentation data, it can be concluded that these programs are very useful for analyzing and predicting the behavior of earth dams. In this study, a variety of instrumentations used in rockfill dams are introduced and common methods and instruments are examined for measuring various geotechnical quantities. The situation of Shahr-e-Bijar Dam, i.e. deformation and seepage, are analyzed using instrumentation data provided by settlement meters and extensometers, which is measured over a relatively long period, and the results of dam modeling via finite element programs. One of the most important steps of dam construction is operation management and maintenance of such projects after design and construction phases. Accordingly, the results of dam monitoring and back analysis are employed to express the importance of these steps as a significant goal of this study and a practical part of dam operation management and maintenance process is also presented by examination of the results of the instrumentation of an earth dam. In summary, two- dimensional numerical modeling of the dam and its foundation is carried out via Plaxis version 8.2 after monitoring the behavior of Shar-e-Bijar Dam based on the information recorded by instrumentation system of the project and the results of numerical modeling are interpreted and compared with those of dam monitoring. Mohr-Coulomb behavioral model must be applied in this research.

Due to the loss of life and damage to surface and underground structures, stabilization of trenches in order to control and stabilize landslides is very important. In the current study, the effect of the implementation of the pile has been analyzed to increase the stability of the trench under the impact of the earthquake. Therefore, a trench with 45 angle which reinforced by the pile, was analyzed with variable parameters, including the diameter of the pile (D) that was with a 0.9m diameter and other pile with 1.5m diameter, the buried length of the pile (L) was 10m and 15m. The space between the piles (S) to each other was implemented by three sizes; 0.3m, 4.5m and 0.6m, and the implementation of the pile with five forms on the span of the trench was analyzed to study its different behavior under seismic conditions. The results showed that with increasing the diameter of the pile and the implementation of the pile, the horizontal displacement of the span of the trench reduces 25% to the normal state. In addition, with an increase in the length of the pile, the level of the subsidence is 24 to 30 percent lower than the normal state.

Commonly used for bonding construction materials, cement has influenced not only construction industry, but also environmental design systems. Mass production of cement from rocks of heavy minerals (plaster of Paris) is known to result in large amounts of mineral waste and requires ball mill processing systems. In this research, partial substitution of cement with eggshell ash in M20 grade concrete at 20, 30, and 40% is considered.