Effect of gypsum dissolution on the stability of embankment dams

Other Title(s)

تأثير إحلال الجبص على ثبات السدود الترابية

Dissertant

al-Tarawinah, Isra Salih Abd Allah

Thesis advisor

Ijam, Abbas Zaki Ulwan

University

Mutah University

Faculty

Faculty of Engineering

Department

Civil Engineering Department

University Country

Jordan

Degree

Master

Degree Date

2018

English Abstract

Gypseous soils are often found in arid and semiarid zones where leaching process of the gypsum from the soil cover is insufficient by the rainfall.

Gypseous soils have good engineering properties in their dry state but when saturated by rainwater or a rising groundwater table, the soluble minerals are washed out, resulting in the subsidence of the structures built on them.

The dissolution of gypsum salts causing caves, increasing the permeability of soils, increases of flow rate due to enlarging fissures and causing excessive settlements, all these causes lead to reduce the efficiency of dams in impounding water if it found in their foundations or abutments.

The aim of this study is to understand the behavior of “earthfill” embankment dams and to check their stability if the gypsum materials are found in the embankment body.

The experimental works were done in civil and environmental engineering laboratory in Mutah University, Alkarak, Jordan.

These experiments were done in two parts.

At first, preliminary tests were carried out in soil mechanics laboratory to investigate the behavior of soil samples containing gypsum salts before the main experiments on the embankment were designed.

Then, seven models of homogeneous embankment dam were constructed in Drainage and Seepage Tank.

These models contained different percentages of gypsum salts (0, 1, 2, 3, 4, 5 and 10%).

From the experiments, three kind of information were obtained from each model.

The first one was the seepage line location were the results showed a rise in the seepage line position as gypsum content increases except for the model of four and ten percent gypsum because the failure that occurred in the downstream slope which forced the phreatic line to change its path.

The second was the variation of water flow rate and dissolution rate with time in that all models tested have not reached the steady state condition either in the outflow or the dissolution rates except the zero and one percent model which reached the steady conditions.

The results also showed that increasing the gypsum content in the soil increases the flow values due to the enlargement of the voids caused by the disintegration of the soil by gypsum dissolution.

The third one was the stability of the embankment during operation and after sudden drawdown where the failure began after adding the 4% gypsum content which means that the dam built with same specifications of the embankment model bear 3%of gypsum content as a maximum limit.

Main Subjects

Civil Engineering

No. of Pages

92

Table of Contents

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-1382051