There have been numerous ways developed to give an economical design of hydraulic structures in order to lessen uplift pressure. Diversion dams and concrete gravity dams are examples of constructions; upstream and downstream of the dam, horizontal aprons or cutoff walls are some of the most important pressure reduction measures. Weep holes, which can be positioned between two cutoffs, are also employed. The main focus of this research is on the influence of weep holes and cutoff on uplift pressure. The Yusefkand Mahabad diversion dam in Iran is the subject of this research. Simulations employing finite element methods are used to determine the solutions (FEM). The influence of weep holes, as well as the effects of position and depth, are studied. Uplift pressure and exit hydraulic gradient were the major outputs used to evaluate the techniques. Perforated PVC pipes with a filter envelope were used to create the weep holes, which relieve excess pore water pressure under a hydraulic structure. This enhances dam stability and avoids piping/internal erosion, which is caused by soil movement. A vertical cutoff wall beneath a hydraulic structure, on the other hand, reduces pore water pressure by increasing the flow channel through the porous material. As a result, putting up a cutoff wall upstream of the dam is a good technique to lower the pressure and hydraulic gradient. In comparison to the no-cutoff-wall situation, an upstream cutoff with an 8 m depth reduces uplift force by 63 percent and the exit hydraulic gradient by 79 percent. Installing a weep hole downstream of a stilling basin reduces uplift force by 8% and the exit hydraulic gradient by 74% compared to not having one. Based on this research, diversion dams can be designed with lower concrete costs, resulting in a more cost-effective design. In reality, when uplift pressure decreases, a thinner concrete structure can be built. This study also includes some additional practical examples that demonstrate the beneficial effects of cutoff walls and weep holes under hydraulic structures.
Author(s) Details:
Farzin. Salmasi,
Department of Water Engineering, Faculty of Agriculture, University of
Tabriz, Tabriz, Iran.
John Abraham,
University of St. Thomas, Minnesota, School of Engineering 2115 Summit
Avenue St. Paul, Minnesota 55105, USA.
Please see the link here: https://stm.bookpi.org/IST-V6/article/view/6032
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