Seepage Analysis Beneath Gravity Concrete Dam Using Flow Net Method and PLAXIS 2D

Dam is a hydraulic structure that built across a river that construct especially for water supply, flood control, energy production, irrigation, recreation, and other. Many problems can occur on the dam construction such as seepage problem, which is seepage need to be controlled in purpose to meet the community’s requirement. In this study, the design and seepage analysis of the construction of a dam built on a river with spanning 400 meters which has a water height of up to 12 meters were carried out. The selection of the solution was obtained based on a numerical method using PLAXIS 2D and analytical analysis with the flow net method of seepage discharge Based on the analysis results, the best solution is obtained by making a dam design that suits the needs where the dam is made with a width of 20 m and a height of 20 m and with the addition of a cut-off structure at the foot of the dam on the left and right sides to a depth of 18 m so that the seepage discharge that occurs in less than 500 m3/day which is meet the community’s requirement. This result indicate that a cutoff wall beneath the dam can reduce and control the seepage on a hydraulic structure, but to design the dam with cutoff wall a couple of analysis need to do to predict the seepage which is with the analysis the seepage problem can be handled.