Civil Engineering Reference
In-Depth Information
Chapter 2
Classical Earth Pressure Theory Related to
Framed Structures
Abstract.
The development of earth pressure theory as it relates to rigidly framed
earth retaining structures is chronicled in this chapter. Inadequacies of classical
theories are explored along with studies related to earth pressure acting against in-
tegral bridges, which resemble, in some ways, a single story rigidly framed earth
retaining structure.
2.1 Introduction
Earth retaining structures have been used for centuries to support vertical or near
vertical soil and rock faces, as well as slopes steeper than their angle of repose.
This class of structures has taken the numerous forms, constructed of various ma-
terials, such as wood, masonry, stone, steel or concrete, or a combination thereof,
with diverse geometries and stability mechanisms.
A very common type of retaining structure is the backfilled retaining wall, of-
ten constructed of timber, masonry, or concrete. Early retaining walls consisted
mostly of stone, masonry or mass concrete, where they derived their resistance to
the retained soil loads from their own weight. These walls are known as gravity
walls. More recently, however, and with the introduction of reinforced concrete,
other types of retaining walls became more dominant, such as the cantilever, semi-
gravity, and counterfort walls, sometimes referred to as structural walls. Unlike
their earlier counterparts, these walls relied on the weight of the retained backfill,
as well as on their own weight, for stability.
Alongside the extensive use of structural walls, other retaining wall systems
were also growing in popularity, examples of which are the crib walls, and the re-
inforced-earth walls. These structures derived their stability from their own weight
and from the strength of the soil retained within them.
Where deep excavations were proposed, in temporary works or on permanent
basis, the earth retention systems of choice took the form of sheet pile walls, dia-
phragm walls, or bored-pile walls. The latter structures were also built with vari-
ous materials, such as wood, steel or concrete, and were often installed in place
prior to the earthwork. They are generally built as cantilevered, anchored, or
braced walls.
