DEPARTMENT OF THE ARMY
ETL 1110-2-352
CECW-ED
U.S. Army Corps of Engineers
CECW-EG
Washington, DC 20314-1000
Technical
Letter No. 1110-2-352
31 March 1994
Engineering and Design
STABILITY OF GRAVITY WALLS
VERTICAL SHEAR
1. Purpose
sufficient to fully mobilize the shear resistance of the
soil.
This engineer technical letter (ETL) provides guid-
ance for incorporating and calculating a shear force
(2) Past practice has been to assign at-rest lateral
acting along the backs of gravity earth retaining walls
earth pressures against the back of the gravity wall
within the procedures for analyzing the stability of
and set the interface friction between the wall and the
navigation structures, including lock walls, and
approach walls. This shear force is also referred to
the back of the wall corresponds to a zero shear force
as a "downdrag" force or "drag" force. The simpli-
along the back of the wall. In addition, boundary
fied procedure described in this ETL for calculating
water pressures were assigned along the back, front,
the magnitude of shear force is restricted to concrete
and base of the wall for navigation structures. With
gravity earth retaining walls founded on rock.
all forces and their points of action on the free body
diagram of the wall defined, wall stability was
checked against the recommended criteria (EM 1110-
2. Applicability
2-1605, EM 1110-2-2502, EM 1110-2-2602,
ETL 1110-2-22, ETL 1110-2-256, ETL 1110-2-310).
This ETL applies to all HQUSACE elements, major
subordinate commands, districts, laboratories, and
b. Experience with existing gravity walls. Past
field operating activities having responsibilities for
practice has been to use the same stability criteria for
the design and construction of civil works projects.
designing new gravity earth retaining structures and
for reviewing the margin of safety available for exist-
ing structures. Several existing structures, although
3. References
not meeting the referenced stability criteria (EM
1110-2-1605, EM 1110-2-2502, EM 1110-2-2602,
References are included in Appendix A.
ETL 1110-2-22, ETL 1110-2-256, ETL 1110-2-310),
have performed satisfactorily for many years. It may
not be necessary to improve a structure's stability to
4. Background
satisfy the referenced criteria when the remaining life
of the structure is relatively short or when there are
a. Calculation of the stability of gravity walls.
no indications of any stability problem. A research
investigation, performed as part of the Repair, Evalu-
(1) A common procedure used for designing new
ation, Maintenance, and Rehabilitation (REMR) Pro-
gravity walls and for evaluating the safety of existing
gram (Ebeling, Duncan, and Clough 1990; Filz and
gravity walls is the conventional equilibrium method
Duncan 1992), was undertaken to study the stability
of analysis. The conventional equilibrium method
of existing concrete structures. The results of the
involves assumptions regarding the loading and resist-
initial REMR research, and the experience from sub-
ing forces that act on the structures. In most cases of
sequent research programs (Ebeling, Duncan, and
massive retaining walls constructed on rock founda-
Clough 1990; Filz and Duncan 1992), are described
tions, movements of the wall and backfill are not
in Sections 4c and 4d of this ETL.
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