Experimental and Numerical Analysis for Earth-Fill Dam Seepage

Ahmed Mohammed Sami Al-Janabi,Zaher Mundher Yaseen,Abdul Halim Ghazali,Yousry Mahmoud Ghazaw,Nadhir Al-Ansari,Haitham Abdulmohsin Afan

doi:10.3390/su12062490

Abstract

Earth-fill dams are the most common types of dam and the most economical choice. However, they are more vulnerable to internal erosion and piping due to seepage problems that are the main causes of dam failure. In this study, the seepage through earth-fill dams was investigated using physical, mathematical, and numerical models. Results from the three methods revealed that both mathematical calculations using L. Casagrande solutions and the SEEP/W numerical model have a plotted seepage line compatible with the observed seepage line in the physical model. However, when the seepage flow intersected the downstream slope and when piping took place, the use of SEEP/W to calculate the flow rate became useless as it was unable to calculate the volume of water flow in pipes. This was revealed by the big difference in results between physical and numerical models in the first physical model, while the results were compatible in the second physical model when the seepage line stayed within the body of the dam and low compacted soil was adopted. Seepage analysis for seven different configurations of an earth-fill dam was conducted using the SEEP/W model at normal and maximum water levels to find the most appropriate configuration among them. The seven dam configurations consisted of four homogenous dams and three zoned dams. Seepage analysis revealed that if sufficient quantity of silty sand soil is available around the proposed dam location, a homogenous earth-fill dam with a medium drain length of 0.5 m thickness is the best design configuration. Otherwise, a zoned earth-fill dam with a central core and 1:0.5 Horizontal to Vertical ratio (H:V) is preferred.

Highlights

The study of seepage through earth-fill dams is very important for constructed dams to ensure that the control of seepage is sufficient for the safe and sustainable operation of the dam
Comparisons revealed that the location of the seepage line obtained from the three methods was almost the same
When the seepage flow intersects the downstream slope and piping takes place, using SEEP/W to calculate flow rate becomes useless as it cannot calculate the volume of water flow in pipes

Summary

Introduction

Research Background Earth-fill (embankment) dams are the most common types of dam. They are considered as the most economical choice when utilizing locally available materials. They have been part of a usual practice to store and control river water for a long time [1,2]. Such dams are normally built by placement and compaction of a complex semi-plastic mound of various soil, rock, sand, or clay compositions [3]. Seepage rate depends on various factors, including the soil medium, the type of fluid, as well as the dams’ geometric conditions [10,11,12]

Objectives

Methods

Discussion

Conclusion