Chapter 6: Retaining Walls

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Section 1: Retaining Wall Selection

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Overview

The project engineer who seals the plans is responsible for ensuring that the retaining wall selected for a given location is appropriate. Use the following criteria to choose a retaining wall:

  • Geometry. Determine applicability of wall type—cut, cut/fill, or fill—based on geometry, site constraints, and wall alignment and location. Identify available right of way. Identify location and type of existing and proposed utilities. Identify location and type of existing and proposed drainage structures.
  • Economics. Evaluate the total cost of wall, including needed excavation shoring. Identify required utility adjustments and costs. Identify project schedule, phasing requirements, and effect on wall construction and design.
  • Stability. Evaluate all walls to ensure that minimum factors of safety are met for global and external stability. When possible, avoid placing walls on slopes. A slope in front of the wall dramatically reduces passive earth pressure (resistance), increasing the probability of wall failure. For situations where walls above a slope cannot be avoided, conduct a rigorous stability analysis following conditions identified in the Design Considerations section of this chapter.
  • Constructibility. Determine whether walls are near water or subject to inundation. Identify access limitations for equipment. Ensure adequate horizontal and vertical clearances are provided for installation of retaining wall types, particularly tied-back, nailed, and drilled shaft walls.
  • Aesthetics. Ensure that the aesthetic treatment of the wall complements the retaining wall and does not disrupt the functionality or selection of wall type. Be careful with aesthetic treatments that involve landscaping: design additional drainage measures if extensive watering is anticipated to prevent excessive hydrostatic pressures from building up behind the wall.

Additional information regarding disregarded depth is available online.

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