Document Type : Research Article
Authors
Ferdowsi University of Mashad
Abstract
Introduction: Today, always some occurrences threat the earth. One of the most important of this event is seepage from earth dam. It can wash interior body of earth dam that finally might ruins whole the earth dam. For investigating these events in this research some experiments for expressing some alternatives to solve this problem in earth dam with clay core were investigated. In first step has been introduced new design in earth dam that it includes earth dam with clay core.
Materials and Methods: In order to determine the height of the filter after the vertical clay core in non-homogeneous earth dam,3 experimental model with length 2/4 meter and a height of one meter and Body slope 1H: 2V was prepared. This model made in Shahrekord University. In flume that has 0.6 meter with, 6-meter length and 1-meter height. This flume has a drain in downstream which determine the discharge through earth dam. Front of flume made glass for visual inspection and behind flume made by steal sheet that was welded. Also, for embankment model, two types of fine-grained and coarse-grained soils were used that determine the range of hydraulic conductivity of soils was performed with Using aggregation experiments model and Soil Mechanics hydrometer. For embankment model use layer have 0.1meter height and this layer was impacted after an after. Finally, dam was built. The slope of models was elected in reference that had normal range and had economical cases. In the first downstream the dam crest was used fine-grained soil and upstream of the dam crest was used coarse-grained soil finally experiment done. In models 2 and 3 with cutting fine grained soil from the toe of the dam to the dam crest vertical clay core was created. The parameter a /L was introduced. A is thickness of clay core and L is the Length base of the dam although in the second model and the third model was selected. Level of water in pound was performed in 3 water height 80 and 55 and 30 and in 3 level of water determinate pressure with 30 embedded piezometers and this data was used in method model .as well as phreatic line was determinate by using of wells and 30 embedded piezometers in the model. Seven holes were instated in body of earth dam in 3 models for visual inspection of phreatic line. In 3 model of earth dam decline clay core in laboratory for show this effect in discharge and phreatic line use Method model. Then the rates of decline in clay core in the laboratory with modeling in software PLAXIS V8.5 were compared. The rate of high filter after the clay core with safety factor 1.2 (Encounter Line Leak with 20% of the bottom filter) was introduced. Finally use SAS software to compare the result of data in filth and software after that comparing show can use software for continue the experiment with Method Model. With change the permeability in PLXIS V8.5 modeling another state. Permeability, this modeling showed that tackiness and permeability of vertical core soil effect in height of vertical filter in downstream. So, can decline this case with choose non-permeability in core. That show in result of this paper. With the class of soil and permeability and change the tackiness of core can estimate height of filter in downstream.
Results and Discussion: Finally, Analysis and comparison between water Failure in interface of fine-grained and coarse-grained soils, both of Software model and laboratory model have a relatively well fit. To obtain the height of Suggested filter, the software model was used to simulate the experiments and Subtracting the thickness of the fine-grained. By applying safety factor of 1.2, Height was designed to filter and after that the clay core was introduced. Software model results show that by increasing clay core thickness the angle of broken-seepage line is increased. Also, the experimental model can emphasize this matter. Finally, by using vertical clay core against the clay core with slop can improve the application of earth dam and by using his plan can improve and diminish the seepage from the earth dam body that this design process was expressed in this research.
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