Note: This article will assume the reader is familiar with the concepts of statics and soil mechanics (mainly the topics of shear strength in soils and effective pressure). 1.1 Introduction Retaining Walls A wall designed with the purpose of keeping a level difference of the soil on its both sides is called a Retaining Wall. These supporting elements can be considered either rigid or flexible. The rigid type are mainly those made of masonry, simple concrete or reinforced concrete. The flexible type are known as sheet pile walls. They are usually made of steel. Retaining walls can also be classified due to their primary function to hold the soil mass. They can be of gravity, cantilever, and counterfort. http://usera.imagecave.com/Cyclovenom/CIMG9836-copy.jpg This is a retaining wall of the gravity type. It is made with masonry units of rocks and mortar. http://usera.imagecave.com/Cyclovenom/Imagen007-copy.jpg This wall is of the cantilever type with steel diagonal supports. It is made of precast concrete sheets. http://usera.imagecave.com/Cyclovenom/Imagen014-copy.jpg This is a gravity wall, but less rigid than the usual. It is known as gabion. It is a very popular solution because gabions are easy to install, economic, offer drainage, and can withstand ground movement better than its counterparts.