ABSTRACT
Deep excavations are expensive works of civil engineering. They usually come about under a civil engineering contract let to a construction company after planning and design by engineers. Fundamentally, for deep excavations, the surrounding ground should remain stable. Several techniques have been developed to install earth retaining walls from the surface before excavating the bulk of soil from the site. Steel sheet piling has been used for many years as earth retaining structures. Contiguous piled walls are formed by constructing rows of bored piles along the alignment for each side of the proposed excavation. Secant piles are also used for constructing walls by forming a row of bored piles in the same way contiguous piles are built in a row. Diaphragm walls are so-named because the panels of reinforced concrete usually have steel reinforcement with structural capacity both horizontally and vertically, and each panel can act as a structural diaphragm. Diaphragm walls are often used for temporary and permanent walls.
