Many dangerous effects arise from seepage through earth dams based on pervious layer. Therefore, the dam embankment must be provided with seepage control measures to avoid such effects. In the present work, different ...Many dangerous effects arise from seepage through earth dams based on pervious layer. Therefore, the dam embankment must be provided with seepage control measures to avoid such effects. In the present work, different control methods were used such as flat slopes, toe drainage systems, and a catch drain in the tail water. The hydraulic performance of each control measure was evaluated using the analytical solutions, previously developed, to estimate the seepage quantity (q), the height of seepage surface (h<sub>3</sub>), and the coordinates of the free surface (h<sub>x</sub>). Study was conducted on a physical model for a dam embankment having a top width (b) = 10.0 meter, height (H<sub>d</sub>) = 30.0 meter, and slope factor (m) = 1.5. The obtained results were analyzed and presented in dimensionless charts. Results showed that, the used control measures possess a great effect on the characteristics of seepage through earth dams based on pervious foundations. A comparative study was conducted between the studied toe drainage systems to enable the designers the better choice for design purposes.展开更多
In the present study, an analytical solution is presented to solve the problem of combined seepage, under a sheet piling cofferdam, applied to dewatering systems. Existence of the sheet pile creates a confined seepage...In the present study, an analytical solution is presented to solve the problem of combined seepage, under a sheet piling cofferdam, applied to dewatering systems. Existence of the sheet pile creates a confined seepage followed by an unconfined seepage in the same field, which presents a combined seepage problem. Two equations were developed to analyze the combined seepage underneath a sheet piling wall. Using such equations, both the maximum height of the free surface just behind the sheet piling cofferdam (H<sub>o</sub>) and the quantity of seepage discharge to be pumped out from the construction site (q) can be determined. The main parameters affecting the combined seepage characteristics underneath a sheet piling wall are: The depth of permeable foundation layer (T), the horizontal distance behind the sheet pile (X), the depth of excavation in the construction site (D), the embedded depth of sheet pile (S), the retained water head (H<sub>1</sub>), the accumulated seepage water depth (H<sub>2</sub>), and the side slope factor of excavation line (M). Study showed that, the above parameters have a great effect on the combined seepage, but with different extents.展开更多
The design protection of the base of the Bratsk HPP （Hydroelectric Power Station） dam from filtration coming from the water reservoir included the arrangement of several cement-grout curtains and the system of drain...The design protection of the base of the Bratsk HPP （Hydroelectric Power Station） dam from filtration coming from the water reservoir included the arrangement of several cement-grout curtains and the system of drainage holes in the 2nd and 4th columns. During operation, increased hydrostatic back pressure at the base of the dam was found, which indicated the low efficiency of the base design protection. To reduce back pressure B. E. Vedeneev Hydro Technic Institute proposed the device of “advanced” drainage holes from the cement-grout gallery near the upstream face. The implementation of the proposal in a number of sections of the dam has led to a decrease in back pressure, but affected filtration in the drainage system, increasing it significantly. The article examines filtration features of “advanced” drainage holes and their dependence on the severity of winters. The spread of the practice of “advanced” drainage in other sections of the dam requires caution and further investigations of the nature of filtration.展开更多
文摘Many dangerous effects arise from seepage through earth dams based on pervious layer. Therefore, the dam embankment must be provided with seepage control measures to avoid such effects. In the present work, different control methods were used such as flat slopes, toe drainage systems, and a catch drain in the tail water. The hydraulic performance of each control measure was evaluated using the analytical solutions, previously developed, to estimate the seepage quantity (q), the height of seepage surface (h<sub>3</sub>), and the coordinates of the free surface (h<sub>x</sub>). Study was conducted on a physical model for a dam embankment having a top width (b) = 10.0 meter, height (H<sub>d</sub>) = 30.0 meter, and slope factor (m) = 1.5. The obtained results were analyzed and presented in dimensionless charts. Results showed that, the used control measures possess a great effect on the characteristics of seepage through earth dams based on pervious foundations. A comparative study was conducted between the studied toe drainage systems to enable the designers the better choice for design purposes.
文摘In the present study, an analytical solution is presented to solve the problem of combined seepage, under a sheet piling cofferdam, applied to dewatering systems. Existence of the sheet pile creates a confined seepage followed by an unconfined seepage in the same field, which presents a combined seepage problem. Two equations were developed to analyze the combined seepage underneath a sheet piling wall. Using such equations, both the maximum height of the free surface just behind the sheet piling cofferdam (H<sub>o</sub>) and the quantity of seepage discharge to be pumped out from the construction site (q) can be determined. The main parameters affecting the combined seepage characteristics underneath a sheet piling wall are: The depth of permeable foundation layer (T), the horizontal distance behind the sheet pile (X), the depth of excavation in the construction site (D), the embedded depth of sheet pile (S), the retained water head (H<sub>1</sub>), the accumulated seepage water depth (H<sub>2</sub>), and the side slope factor of excavation line (M). Study showed that, the above parameters have a great effect on the combined seepage, but with different extents.
文摘The design protection of the base of the Bratsk HPP （Hydroelectric Power Station） dam from filtration coming from the water reservoir included the arrangement of several cement-grout curtains and the system of drainage holes in the 2nd and 4th columns. During operation, increased hydrostatic back pressure at the base of the dam was found, which indicated the low efficiency of the base design protection. To reduce back pressure B. E. Vedeneev Hydro Technic Institute proposed the device of “advanced” drainage holes from the cement-grout gallery near the upstream face. The implementation of the proposal in a number of sections of the dam has led to a decrease in back pressure, but affected filtration in the drainage system, increasing it significantly. The article examines filtration features of “advanced” drainage holes and their dependence on the severity of winters. The spread of the practice of “advanced” drainage in other sections of the dam requires caution and further investigations of the nature of filtration.
