Civil Engineering Reference
In-Depth Information
Chapter 7
Parametric Study of Earth Pressure behind
RFERS at Backfill Stage
Abstract.
This chapter presents the results of parametric finite element analyses
performed to explore the relationship between earth pressure and the stiffness of
Rigidly Framed Earth Retaining Structures (RFERS). A plane strain model was
employed. The stages of construction were incorporated in the analysis to simulate
an initial stage where a structural frame is first completed followed by the addition
of backfill soil in several stages. The displacement of the structures, as well as the
earth pressure and resultant load developed behind them were obtained to examine
the relationship between the stiffness of the retaining structure and the
development of lateral earth pressure in the retained soil mass.
7.1 Introduction
All retaining structures undergo some form of displacement after the application
of lateral earth pressure before reaching a state of equilibrium. The lateral part of
the displacement transforms the state of stress in the ground depending on the
amount and type of displacement (FHWA, 1976 pp 32). An infinitely rigid
retaining wall, for instance, may undergo lateral displacements in the form of pure
translation, rotation about the bottom, rotation about the top, or a combination
thereof. A flexible wall, on the other hand, may undergo the same type of
displacements as a rigid wall, in addition to displaying flexure under lateral loads.
Moreover, flexible retaining walls which are braced or tied may also undergo
similar displacement types but with different flexural deformation characteristics.
The state of stress in the retained soil mass is generally dependent on the type
of displacement and the shape of the displaced retaining structure (Winterkorn and
Fang, 1975 pp 216-218). Fig. 7.1 (Finn, 1963) presents elastic solutions for lateral
pressures on walls produced by two types of lateral displacement namely
translation and rotation about the bottom. The resultant lateral load is shown to
vary with the type of wall displacement for the same material.
Despite the existence of a voluminous amount of literature and research work
on the subject of lateral earth pressure for various types of retaining structures and
soil material, nevertheless, the authors are not aware of any research or published
