TM 5-818-1 / AFM 88-3, Chap. 7
Table 14-3. Design Considerations for Braced and Tieback Walls-Continued
Design Factor
Comments
8. Preloading
Useful to remove slack from system and minimize soil movements .Preload
up to the load diagram loads (fig. 14-10) to minimize movements
9. Construction sequence
Sequence used to build wall important in loads and movements of system.
Moments in walls should be checked at every major construction stage
for maximum condition. Upper struts should be installed early
10. Temperature
Struts subject to load fluctuation due to temperature loads; may be impor-
tant for long struts
11. Frost penetration
In very cold climates, frost penetration can cause significant loading on
wall system. Design of upper portion of system should be conservative.
Anchors may have to be heated
12. Earthquakes
Seismic loads may be induced during earthquake. Local codes often govern
13. Codes
For shallow excavations, codes completely specify support system.Varies
from locality to locality. Consult OSHA requirements
Minimum Design
14. Factors of safety
Item
Factor of Safety
Earth Berms
2.0
Critical Slopes
1.5
Noncritical Slopes
1.2
Basal Heave
1.5
General Stability
1.5
14-16
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