γt = total unit weight of backfill

(1) To develop an improved understanding of the

interaction between gravity walls, their foundations,

and their backfills, an investigation using finite ele-

(2) Analyses indicated that the gravity walls

ment analyses was conducted (Ebeling et al. 1992;

would move only a very small amount during place-

Ebeling, Duncan, and Clough 1990). The analyses

ment of the toe fills and backfills. As a result, the

demonstrated that the backfill settles relative to the

earth pressures on the backs and the fronts of the

wall and develops downward shear loads on the wall.

walls are close to those that exist at rest. Even so,

Some examples are given in Figure 1, which shows

settlement of the backfill relative to the wall as it is

the results of finite element analyses of four walls

placed behind the wall is sufficient to generate a

founded on rock and retaining dry backfill. In Fig-

significant amount of shear force on the wall. Values

of *K*v range from 0.09 to 0.21 for the four cases

expressed in terms of a vertical shear coefficient *K*v,

shown in Figure 1.

which is related to the shear force on the vertical

plane through the heel of a wall by the following

(3) Parametric studies demonstrated that the most

equation:

concrete gravity walls on rock foundations are the

1

γt H 2

(1)

inclination of the back of the wall, and the number of

2

steps in the back of the wall. The following trends

were observed:

where

(a) For low walls, the value of *K*v increases with

increasing wall height because more backfill compres-

heel of the wall (force per unit length of wall)

sion occurs due to self-weight of the backfill. The

resulting increase in differential movement between

2

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