This thirty-second manual in the GEO5 engineering series provides a comprehensive guide to performing a steady-state seepage analysis of an earth dam using the Finite Element Method (FEM) in GEO5. The manual focuses on determining the location of the phreatic line within a homogeneous earth dam and assessing the distribution of pore pressures and water flow velocities. Available for download, this manual is essential for geotechnical engineers involved in the analysis and design of earth dams and other water-retaining structures.

Learning Objective:

The goal of this manual is to teach users how to conduct a steady-state seepage analysis using the GEO5 FEM Water Flow program. Users will learn how to define the geometry of the dam, input material properties, apply hydraulic boundary conditions, and interpret the results to locate the phreatic line and assess the dam’s stability under various water levels.

Assignment Description:

In this assignment, users are tasked with analyzing the seepage through a homogeneous earth dam under different water levels in the reservoir. The analysis involves setting up the geometry of the dam, defining the material properties, and applying boundary conditions for three scenarios: water levels at 2 m, 9 m, and 10.8 m above the terrain surface. The manual provides step-by-step instructions for setting up the problem, performing the analysis, and interpreting the results to determine the location of the phreatic line and the potential for water discharge at the downstream face.

Outcome:

Upon completing this assignment, users will be able to accurately model and analyze steady-state seepage through earth dams using GEO5 FEM software. They will gain practical experience in setting up seepage models, interpreting the results for phreatic line location, pore pressure distribution, and water flow velocities, and ensuring that the dam meets safety and performance criteria.

Conclusions:

The manual concludes that the location and shape of the phreatic line depend solely on the boundary conditions, geometry, and material properties of the dam. The analysis shows that for water levels at 2 m and 9 m, outflow occurs only below the terrain surface, while at 10.8 m, the phreatic line reaches the downstream face, resulting in surface outflow. These results emphasize the importance of accurate seepage analysis for ensuring the stability and safety of earth dams.

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