Geotechnical Engineering: Moving Beyond Empirical To Analytical
DP- 82 Mechanically Stabilized Earth (MSE) Walls and Slopes
DP-83 Structure Foundations
   - Pile Foundations (Old DP-66)
   - Design of Highway Bridges for Extreme Events
DP-103 Soil Nail Walls
AP-21 Geotechnical Engineering Aids
   - Geotechnical Microcomputer Programs
   - Geotechnical Engineering Circulars

Geotechnical engineering has been critical to highway construction since engineers realized that successful civil works depended on the strength and integrity of the foundation material. Classical geotechnical engineering is usually linked to the pioneering work of Karl Terzhagi, who proposed many of the concepts and relationships upon which today's geotechnical practice is based.

Much of the work in recent years has been to improve on Terzhagi's empirical relationships with the analyses based on rational formulae, field data, and high-speed computers, which make sophisticated analysis possible. As an example, empirical pile driving formulae (for example, the ENR formula) have been replaced with pile driving requirements based on the Pile Dynamic Analyzer (PDA), as demonstrated in OTA's Demonstration Project 66. (No longer active)

Analysis, design, and construction methods have improved dramatically in recent years as a result of concentrated research, development, and technology transfer efforts. Added to this has been the extensive experience gained by demonstration projects on pile foundations (DP-66) and permanent ground anchors (DP-68). The development of microcomputer-based geotechnical software has also accelerated replacement of simplistic empirical methods with rigid analytical procedures.

While the engineering developments have been dramatic, there needs to be technology delivery and technical assistance to support application of these new procedures. The following seven activities will provide innovative technology and new developments in geotechnical engineering to a widespread community of geotechnical, construction and structural engineers:

  1. Beta test and distribute final user-friendly microcomputer programs for design of geotechnical features. Programs under development are MSEW (Mechanically Stabilized Earth Walls), RSS (Reinforced Soil Slopes), Driven, and DEEP.

  2. Conduct a "Conference on Design of Highway Bridges for Extreme Events."

  3. Establish a recommended design method for extreme design conditions on bridges, including ship impacts, scour, and seismic events; issue an FHWA Technical Advisory; conduct a national conference to disseminate technical information on the recommended design method(s) for extreme design conditions and status of the R&D program to develop an improved method.

  4. Implement the results of the geotechnical R&D program to define an improved method of bridge design for extreme events by incorporating the results in the AASHTO code.

  5. Update technical guidance on driven pile foundations and provide NHI training to transportation engineers in design and construction monitoring of deep foundations.

  6. Develop and publish a comprehensive series of Geotechnical Engineering Circulars as state-of-the-art resources on geotechnical engineering practice.

  7. Develop and present a training course on application of the Load and Resistance Factor Design (LRFD) code to design of highway bridge foundations, retaining walls and other geotechnical engineering features.

Project Coordinator
Chien-Tan Chang, HTA-20, (202) 366-6749

U.S. Department of Transportation
Federal Highway Administration