Engineering and Construction

As mentioned in the previous section, in order for the active wedge (Fig. 11.3) to be developed, there must be sufficient movement of the retaining wall (Table 11.1). There are many cases where movement of the retaining wall is restricted. Examples include massive bridge abutments, rigid basement walls, and retaining walls that are anchored in non-yielding rock. These cases are often described as restrained retaining walls.

In order to determine the earth pressure acting on a restrained retaining wall, Eq. 11.1 can be utilized where the coefficient of earth pressure at rest (ko) is substituted for kA. The value of ko can be estimated from Eqs. 4.19 and 4.20. A common value of ko that is used for restrained retaining walls is 0.5. Restrained retaining walls are especially susceptible to higher earth pressures induced by heavy compaction equipment and extra care must be taken during the compaction of backfill for restrained retaining walls.


For either a line load or point load acting on the ground surface behind the restrained retaining wall, Fig. 11.8 can be used to determine the additional horizontal force PH acting on the restrained retaining wall and the location of this horizontal force above the base of the wall. The upper plots in Fig. 11.8 can be used to determine the horizontal pressure distribution acting on the retaining wall due to the line load or point load.

If there is a uniform surcharge Q acting upon the entire ground surface behind the wall, then there would be an additional horizontal pressure exerted upon the restrained retaining wall equal to the product of ko
times Q. Thus the resultant force P Q, in pounds per linear foot of wall or kilonewtons per linear meter of wall, could be calculated by using Eq. 11.3 and substituting ko for kA.


In summary, for the retaining wall shown in Fig. 11.5, the values of the earth pressure acting on the wall are as follows: