7:30 am

Registration and Continental Breakfast
 

8:00 am

Welcome
 
Distinguished University Representative
University of Minnesota
 

8:15 am

Kersten Lecture
Geosynthetic Reinforced Soil: From the Experimental to the Familiar

Robert D. Holtz, Ph.D., P.E., D.GE
Professor Emeritus
University of Washington, Seattle, WA

The lecture begins with a historical review of reinforced soil technology. The advantages and basic behavior of geosynthetic reinforced soil (GRS) are presented along with an overview of current design procedures and with reference to university research results. Practical suggestions are given for dealing with creep, pullout, and backfill drainage. Geosynthetic properties are then discussed, again with reference to university research. Although GRS is quite a mature development, a few technical and professional issues remain; primarily, too many failures of these structures occur. Reasons for these failures and some suggestions as to what the profession can do about them are presented. The lecture ends with several examples of successful applications of GRS and reinforced soil technology.
 

9:20 am

On the Earth Pressure Cell with Case Histories

Joseph F. Labuz, Ph.D., P.E.
MSES/Miles Kersten Professor
University of Minnesota, Minneapolis, MN

Perhaps the most maligned transducer in geotechnical engineering is the earth pressure cell (EPC), a device used to determine normal stress on a plane within a soil mass or at a soil-structure interface. Essentially, the response of an EPC is governed by force equilibrium, and the difficulty with the interpretation of the transduction process involves the actual distribution of normal stress and a possible arching phenomenon, which can lead to either over- or under-registration of a given normal stress. Furthermore, the transducer itself may complicate the measurement because of a perturbation of the stress field, although this inclusion effect is reduced through proper design of the EPC. The structural response of an EPC will be reviewed, and calibration procedures for evaluating nonuniform normal stress and arching will be discussed. Two case histories will be presented to demonstrate that, with consistent placement procedures and proper calibration, the EPC can provide meaningful data for evaluation of performance.
 

10:00 am

Break
 

10:30 am

Performance Monitoring and Construction Control: Woodrow Wilson Bridge - Maryland Portion

Barry R. Christopher, Ph.D., P.E.
Geotechnical Engineering Consultant
Atlanta, GA

This presentation will provide a description of the geotechnical challenges and solutions used for the Woodrow Wilson Bridge replacement project on the Maryland side of the Potomac River. This section of the project required construction of an asymmetrical embankment over highly differential soil conditions. Geotechnical features that will be reviewed include the use of extremely high strength geotextile reinforcements to improve the support conditions under the embankments, piled supported embankments used in one section where rubbilized fill was encountered, and light weight fill to decrease wall loads to address stability issues. In addition, an extensive instrumentation program in critical sections to control risk during construction will be presented.
 

11:10 am

Applied Unsaturated Soil Mechanics

Sandra L. Houston, Ph.D.
Professor of Civil Engineering
Arizona State University, Tempe, AZ

Construction in unsaturated soils is dominant due to relative ease of construction above the groundwater table. Additionally, geoenvironmental applications are strongly dependent on unsaturated soil properties and behavior. Unsaturated soils have a tendency to be sensitive to the moisture content increases that accompany urbanization, which accentuates the importance of unsaturated soil mechanics for design and construction. There is evidence that the design changes between doing typical and doing extensive geotechnical testing and analysis on unsaturated soils can be extremely significant. Therefore, the motivation for implementation of unsaturated soil mechanics into geotechnical practice is great. The adoption of a hierarchical approach to encourage routine use of unsaturated soil mechanics theory is recommended.
 

11:50 am

Lunch
 

1:00 pm

GeoRisk in the Business Environment

William Brumund, Ph.D., P.E.
Golder Associates
Jacksonville, FL

Companies are exposed to many georisks that arise from work done on engineering projects or are not specifically related to performance on a project. This paper considers risks that may arise from the characterization of the subsurface conditions and how engineers conceptualize and model these conditions and related uncertainties. One of the areas of greatest exposure to companies is incorrectly defining the mode(s) of deformation or failure (the conceptual model). Business risks can arise from large, long-term projects, from events that are rare, have extreme impacts, and are unpredictable or extremely difficult to predict. The limitations and business risks for companies that have project opportunities in OFAC countries is also discussed.
 

1:40 pm

Why Monitor Geotechnical Performance?

W. Allen Marr, Ph.D., P.E.
President and CEO
Geocomp Corporation, Acton, MA

The reasons for monitoring geotechnical performance will be reviewed and discussed to help engineers develop justifications for geotechnical instrumentation programs on their projects. A simplified method will be presented for estimating the potential benefits of a geotechnical instrumentation program. This method can help engineers estimate how much of a geotechnical instrumentation program is justified for a project to reduce the risk costs from uncertainties, damages, and delays.
 

2:20 pm

Break
 

2:50 pm

Contribution of Case Histories for Design and Installation of Driven Piling

James H. Long, Ph.D.
Associate Professor
University of Illinois, Urbana, IL

Case histories provide essential information for improving the design and installation of driven piling. A review of a large number of case histories provides perspective and an overall sense of reliability for which predictions can be made. Several individual case histories will be discussed to illustrate the importance of time effects, the difference between capacity based on driving behavior and capacity based on static load tests, or restrikes, and driving behavior of closed in pipe piles versus H-piles. Results of database studies provide an overall perspective of how well predicted and measured capacity agree. These results are presented in terms of simple graphs and statistics. The impact these results have on selecting appropriate resistance factors in LRFD design is discussed.
  

3:30 pm

Case History 1

Shear Strength of Lake Agassiz Clays and its Role in Slope Stability

Ivan A. Contreras, Ph.D., P.E.
Barr Engineering Company
Minneapolis, Minnesota

Slope instability along the banks of the Red River and its tributaries is a common phenomenon observed where “Lake Agassiz Clays” are present. Lake Agassiz clays have been recognized as a poor foundation material and they are often characterized as soft clays. However, it has been observed that these clays exhibit a medium to stiff consistency and that the presence of fissures and micro-fissures play a major role in the softening phenomena and mobilization of their shear strength. The paper presents the results of an extensive laboratory testing program in Lake Agassiz clays and illustrates the role of the shear strength on the stability analysis and stabilization measures of landslides in these clays
 

4:00 pm

Case History 2

Measured Live Load Effects on Driven Pipe Piles with Established Dragload

Derrick D. Dasenbrock, P.E..
Minnesota Department of Transportation
Maplewood, Minnesota

The north abutment of Minnesota Department of Transportation Bridge 27R20 was outfitted with 12 vibrating-wire strain gages distributed along each of two production piles. The sensors were used to examine the behavior of the instrumented piling under live load conditions. The study showed that dead load, dragload, and live load can coexist. Data from the live load tests suggests that the live loading, as well as dead load applied after consolidation settlement was complete, is distributed differently along the pile than initial dragload and early construction dead loads. Additional observations related to the data from the live load test and data acquired following the test, after the span was open to regular vehicle traffic, are discussed.
 

4:30 pm

Adjournment