7:30 am

Registration and Continental Breakfast
 

8:15 am

Welcome
Robert Ballarini, Ph.D.
Record Professor & Head, Civil Engineering
University of Minnesota
 

8:25 am

Kersten Lecture
Integration of Geotechnical and Structural Design in Tunneling

Evert Hoek, Ph.D.
Consulting Engineer
North Vancouver, BC, Canada

In the majority of modern rock tunnels the deformation and hence the stability of the tunnel is controlled by a combination of reinforcement and support systems. The reinforcement consists of rockbolts or cables which modify the properties of the rock mass in much the same was as reinforcement does in concrete. The support systems generally involve steel sets or lattice girders fully embedded in shotcrete and these provide resistance to control the convergence of the tunnel. This paper describes the methods that can be used to optimize the design of tunnels using a combination of reinforcement and support methods. Particular attention is given to tunnels in very weak rock or soil in which large deformations can occur. A case history of a 36 foot span two lane highway tunnel, excavated by top heading and benching in a very weak rock mass, is presented to illustrate the integration of geotechnical and structural design methods.
 

9:20 am

Enzyme Products for Subgrade Stabilization

Mihai Marasteanu, Ph.D.
Associate Professor, Civil Engineering
University of Minnesota

The subgrade stabilization effectiveness of two enzyme products was investigated using resilient modulus testing and chemical analysis. Two types of soil and two types of enzyme products were tested. The resilient modulus results indicate significant differences between the four stabilized soils. The soil clay content and percent of fines appear to play an important role in the effectiveness of enzyme-based stabilizer treatment. The limited effectiveness of one of the enzyme products appears to be due to its surfactant-like characteristics while the other product, which was effective for both soils, exhibited no surfactant-like characteristics.
 

10:00 am

Break
 

10:30 am

Soil Strength and Slope Stability

Steve Wright, Ph.D.
Brunswick-Abernathy Regents Professor, Civil Engineering
University of Texas at Austin

The stability of earth slopes is commonly evaluated using one or more procedures of limit equilibrium slope stability analyses to compute a factor of safety that is defined with respect to shear strength. Depending on the particular loading and slope conditions the appropriate shear strength may be either the undrained or drained shear strength, and either short-term or long-term stability may govern. This paper addresses the importance of using the proper (drained or undrained) shear strength and evaluating the short-term and long-term stability conditions to establish the most critical condition and minimum factor of safety.
 

11:10 am

Rapidly Deployed, Geo-based Systems for Blast Resistance

Richard A. Reid, Ph.D.
Professor & Assistant Dean of Engineering
South Dakota State University, Brookings

Prior to the end of the 20th century, the design and construction of facilities to resist explosions was a consideration typically addressed in high military threat areas or in some industrial facilities. The advent of worldwide terrorism has introduced a new threat to a much wider target set that now includes public buildings, infrastructure, businesses, industrial buildings and individuals. Due to the potential for catastrophic damage, economic and political implications, loss of life and the subsequent psychological impact on the public engineers may be asked to design systems to provide protection and deter this threat. This paper will briefly discuss the background and history of systems designed to resist explosions, general design considerations, and introduce some geo-based systems and their effectiveness.
 

11:50 am

Lunch
 

1:10 pm

Practical Aspects of Implementation of AASHTO-LRFD Procedures

Naresh C. Samtini, Ph.D., P.E.
NCS Consultants
Tucson, Arizona

State and local transportation agencies throughout the US are at various stages of implementation of the Load and Resistance Factor Design (LRFD) as specified by the American Association of State and Highway Transportation Officials (AASHTO). Based on the author’s experience in helping several agencies with implementation of LRFD, this paper will outline practical aspects that may aid in proper implementation of the LRFD approach. Aspects such as live load model, redundancy in deep foundation design, relevance of differential settlement, overstress allowances, concept of limit states, calibration to local geologic conditions, etc. will be outlined and briefly discussed.
 

1:50 pm

Intelligent Compaction: From Theory to Practice

David J. White, Ph.D.
Wegner Associate Professor, Civil Engineering
Iowa State University

The successful implementation of intelligent compaction (IC) technology into earthwork construction practice requires knowledge of the IC measurement values and their relationship to machine operations and various in-situ compaction measurements. This paper/presentation will describe experimental methods to investigate the relationships between in-situ and IC measurement values for a wide range of soils. Based on analysis results and a statistical framework for incorporating measurement variation, guidelines for QC/QA procedures are proposed.
 

2:30 pm

Break
 

3:00 pm

Case Histories

Concurrent Session 1A:
Auger Cast Displacement Piles

Steven D. Gerber, P.E.
Terracon Consultants, Inc.
White Bear Lake, Minnesota

A project site with deep deposits of loose, non-plastic silt and shallow groundwater presented challenges in designing an effective foundation support for heavily loaded structures. Consideration was given to supporting the proposed structures on stone columns; however, stone columns would not likely achieve the high bearing pressure and presented challenges with below grade structures. Auger cast piles were selected as the preferred foundation support alternative. However, there was concern with using traditional auger cast piles due to the likelihood of over rotating the augers during construction. Displacement piles, in contrast, would not remove soil, would likely increase the lateral stresses and generate positive group effects on capacity. Overall the piles were found to be effective and constructible, although there were minor difficulties arising from liquefaction of the silt by the construction.
 

Concurrent Session 1B:
Managing Storm Water with Hot Mix Asphalt Pavements

Jill M. Thomas, P.E.
Minnesota Asphalt Pavement Association
New Brighton, Minnesota

Managing storm water with porous or dense graded hot-mix asphalt (HMA) pavements is attracting attention because of the role it can play in sustainable site design and storm water management. This technology is of interest to public works officials, consultants, engineers, land developers, contractors, environmental engineers, and others with an interest in minimizing the impact of development on the environment. This pavement structure has been used in various climate conditions and can provide the many benefits including: storm water runoff control, groundwater recharge, reduction of drainage structures needed to comply with storm water regulations, reduction of right-of-way for extra retention ponds, reduction of curb and gutter and increased skid resistance and safety.
 

3:30 pm

Case Histories

Concurrent Session 2A:
Blast Vibration Predictions, Damage Assessment and Vibration Monitoring for a Medical Center Expansion

Lee Petersen, Ph.D., P.E.
CNA Consulting Engineers
Minneapolis, Minnesota

The 2003-2004 expansion of a Duluth medical center required rock blasting adjacent to the existing structures, a Mn/DOT retaining wall and other urban structures. This case history describes the methods and results of a blast damage assessment, based on blast parameters, excavation locations, and critical vibration receptors (including surgical suites, a linear accelerator and a major retaining wall). The assessment concluded that blast vibrations would not impact any of the critical receptors. During construction, we reviewed submittals, observed test blasts, reviewed blasting logs and monitored blasting vibrations. Up to 13 seismographs were used simultaneously. Close coordination with medical center operations personnel was necessary to prevent impacts to critical medical procedures. Measured vibrations were clustered around the predicted values, and attenuated at the predicted rate. High-frequency blast vibrations induced low-frequency vibration of the retaining wall. Medical center structures significantly attenuated the ground-borne vibrations.
 

Concurrent Session 2B:
Consolidation of Peat Deposits at Lake of the Isles

Brian Albrecht, Ph.D, P.E.
SEH, Inc.
St. Paul, Minnesota

Since its creation in the early 1900s, Lake of the Isles Park in Minneapolis, Minnesota has been settling. The trails and park space have experienced frequent flooding, even during normal rainfall events. The Minneapolis Park and Recreation Board completed several park renovation projects between 2001 and 2007, two of which used surcharge loading to pre-consolidate peat deposits. This paper summarizes the investigation, testing, design process and monitoring of settlement during these two projects. It appears that surcharging peat deposits to improve open space is feasible at low vertical stress increases, less than 500 psf, when deposit thickness is less than 15 ft. However, methods other than surcharging, or in addition to surcharging, should be considered if more significant stress increases are needed to achieve desired grades.
 

4:00 pm

Case Histories

Concurrent Session 3A:
Electrical Resistivity Imaging in Minnesota

Jason Richter, P.G.
Minnesota Department of Transportation
Maplewood, Minnesota

Electrical Resistivity Imaging (ERI) has become an effective supplement to the subsurface investigation process at the Minnesota Department of Transportation. Mn/DOT has employed ERI on a variety of projects encompassing the scoping, pre-construction and post-construction phases. This lecture will present the findings from electrical resistivity imaging performed on projects related to bridge and roadway design, subsidence/cavity detection, and identification of buried organic/compressible soils.
 

Concurrent Session 3B:
Use of Horizontal Drains for Slope Stabilization

Jed Greenwood, P.E.
Barr Engineering, Co.
Minneapolis, Minnesota

Drainage is an effective approach of stabilizing landslides. This stabilization principle is based on the reduction of pore-water pressures on the slip surface, which increases the effective stresses and thus increases the stability of the slope. This technique is most effective where the geological conditions are conducive to manmade interference with the natural groundwater regime. This technique has been used by the authors successfully on multiple projects.
The paper presents two case histories of slope stabilization using horizontal drains. The first case involves a railroad embankment in northern Minnesota. The second case involves a slope at a petrochemical plant in Houston, Texas. In both cases, monitoring evidence of the effect of the drains in drawing down the groundwater and subsequent slope stabilization are presented and discussed.
 

4:30 pm

Adjournment