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FHWA Apparent Lateral Earth Pressures

FHWA Apparent Pressures in Deep Excavations


FHWA Apparent Pressure Diagrams

FHWA apparent earth pressure diagrams are prescribed by the Federal Highway Administration for design purposes of vertical "flexible" retaining walls for transportation projects. FHWA recommends a number of diagrams that depend on soil type, and number of brace supports. In general, FHWA recommends using trapezoidal earth pressure diagrams that derive from active earth pressures times a factor that ranges from 1.1 to 1.3. For undrained clays a multiplication factor of 0.2 to 0.4 is recommended. One of the oversights of FHWA is that the apparent earth pressure diagrams reduce to zero at the excavation base. Applying zero earth pressure at subrade can result in undersizing of the required wall embedment. As engineers we should recognize the limitations inhereted with apparent earth pressure diagrams. For this reason, FHWA apparent earth pressure diagrams should be used as preliminary tools that can complement more comprehensive non-linear solutions.


Figure 1 below shows the basic FHWA recommendations for apparent earth pressure diagrams. Figure 2 shows an apparent earth pressure diagram as calculated by our DeepEX software program.

Figure 1: Basic recommendations by FHWA


Figure 2: FHWA Apparent Pressures Diagrams - DeepEX Software

 

DeepEX Software can Calculate all Soil Pressure Types for Deep Excavations Active/Passive, At-Rest, Peck Apparent, FHWA Apparent, Custom Trapezoidal, AASHTO 17 and more!


 

Solutions for Geotechnical Engineering Professionals:


DeepEX: Deep Excavations Design Software

DeepEX: Deep Excavations Design Software




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DeepFND: Pile Foundations Design Software




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HelixPile Helical Piles Design Software




SnailPlus: Soil Nail Walls Design Software

SnailPlus: Soil Nail Walls Design Software





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