1. Research Needs: The Academic Perspective
International Workshop on Micropiles 2003
Research Needs: The Academic Perspective by
Adrian Rodriguez-Marek
Washington State University
Seattle, September 2003
Say: My objective is to paint a picture of where we have the greatest need for research. This is not a lecture on the state of the art of research, but rather the creation of a “laundry-list” of items where research within the academic community can result in an improvement in practice. I will make mention to where research has been done, but by no means I will paint a comprehensive picture of the state of the art in research.

2. Outline User driven research needs Tools for performance prediction
Design methodology
“Academic” driven research
Advancement of the State of the Art of methods for performance prediction

3. Design Specifications
Practical design tools
Capacity
Displacement
Design Specifications
State of the Art Methods
Behavior Prediction
Soil-Micropile- Structure Interaction

4. User-Driven research needs
p-y curves
“Shadow effect”:
Currently: use factors from drilled shafts or pile groups
Does s/d extrapolate to small diameter micropiles?
Scale effects
Scale effects: in dense sands, research for large diameters CIDH piles showed insensitivity of p-y curve stiffness to diameters. Not so in loose sand.

5. User-Driven research needs
Simplified design methods: group efficiency factors
No database of field tests to correlate factors with performance

6. User-Driven research needs
Guidelines for structural design
What is the fixity condition?
Connection detailing
Full Scale Field tests are needed

7. FIELD AND MODEL TESTING
Practical design tools
Capacity
Displacement
Design Specifications
State of the Art Methods
Behavior Predicition
Soil-Micropile-Structure Interaction

8. Role of Academia Partnership with industry to perform field tests
Dissemination
Peer-review
Quality control
Push for testing in projects involving Micropiles
Innovation in testing methodologies
Is the Micropile-soil mass behaving as a unit?

9. Advancement of the State of the Art
State of the art tools for performance assessment
Numerical Tools: FE, FD
3-D, Dynamic
Adequate modeling of Boundary Conditions
Constitutive models of soil behavior
Evaluation of “as-built” Micropiles
Non-destructive evaluation methods
Effects of construction methodology on soil properties

10. Advancement of the State of the Art
Constitutive Models for Dynamic Soil Behavior
Must be able to describe change of stiffness and damping with strain
Must be able to adequately describe small strain non-linearity
Must adequately model effect of confining pressure on stiffness
Essential for Networks

11. Advancement of the State of the Art
Effects of construction method
Soil model must be sensitive to the effect of increased confining stress due to network effects
How do soil properties change with Micropile construction?
Cavity expansion modeling

12. Non-destructive Testing
Three problems with NDE techniques
High length-diameter ratios
Non-uniform diameters
Small diameter heads

13. Role of Academia Technology “transfer” Model Development
Models that at the same time have confining-stress dependent stiffness, small strain nonlinearity, adequate large strain non-linearity
Models that incorporate elemental soil behavior (e.g. state-parameter based models)

14. Role of Academia
Analysis of full soil-pile-structure interaction problems
Structural detailing: model and full scale tests