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Friday, February 23, 2018

7:30 am Registration and Continental Breakfast
8:15 am Introduction & Welcome, Room 135
Chris Behling, Chair
Chief, Geotechnical and Geology Section
U.S. Army Corps of Engineers
St. Paul District
Mos Kaveh, Interim Dean
College of Science & Engineering
Professor, Electrical & Computer Engineering
University of Minnesota
8:25 am Kersten Lecture
Protecting the Environment with Geosynthetics: a Perspective

Kerry Rowe, NAE, P.Eng., Ph.D.
Professor, Civil Engineering
Queen's University, Kingston, Ontario, Canada

Geosynthetics are now widely used to contain fluids and protect the environment. Applications include most modern landfills, lagoons for contaminated fluid and drinking water, dams, and mining applications such as heap leach pads and in tailings storage facilities where loss of fluid to surface water or groundwater must be minimized. These systems often involve a single liner with welded panels of geomembrane liner, a geosynthetic clay liner, or a composite liner with a geomembrane over a clay liner. For large landfills or other higher-risk applications, a double liner system with a geocomposite or granular drain between two liners is used. Most frequently designs have used materials that meet a minimum set of commonly specified index parameters. This lecture draws together field observations, long-term experimental data, and theory to show how, and why, these systems have worked so well while highlighting the importance of design and construction considerations that, if overlooked, can cause problems. It then discusses the means of avoiding pitfalls.

9:20 am Paul-Mohr-Coulomb Failure Criterion for Rock and Soil

Joseph Labuz, P.E., Ph.D.
MSES/Kersten Professor, Civil, Environmental & Geo- Engineering
University of Minnesota, Twin Cities

The popular Mohr-Coulomb (MC) failure criterion is a reasonable approximation to strength data for both rock and soil, featuring a linear relation between major and minor principal stresses. Criticisms of MC are the absence of the intermediate principal stress and the inability to represent a curved failure surface. Paul-Mohr-Coulomb (PMC) removes these limitations by (a) including all three principal stresses and (b) approximating a nonlinear failure surface with piecewise linear segments. The material parameters for PMC are (1) the friction angle for axisymmetric compression, (2) the friction angle for axisymmetric extension, and (3) a strength parameter such as the (theoretical) isotropic tensile strength. Failure criteria are reviewed and experimental data for several rocks and soils are used to evaluate the PMC material parameters. The results show that the friction angle in extension is larger than the friction angle in compression, indicating an intermediate stress effect.

10:00 am Break: Upper Lobby, Refreshments & Snacks
10:30 am Design and Installation Monitoring of Helical Piles and Anchors

Alan Lutenegger, P.E., Ph.D.
Professor, Civil and Environmental Engineering
University of Massachusetts, Amherst, Massachusetts

The basic design procedures used to estimate the capacity of helical piles and anchors are reviewed. Engineers face a number of design challenges that relate to the specific geometry of the helical pile or anchor, i.e. number, size, and spacing of helical plates; and size and shape of the central shaft. The behavior of helical piles and anchors also depends on the quality of the installation. Poor quality installation generally produces poor performance. Key parameters for monitoring installation of helical piles and anchors will be described and examples will be presented illustrating typical results from installation monitoring and the impact of poor quality installation on behavior.

11:10 am Evolution of USACE Seepage Barrier Wall Contracts

Georgette Hlepas, P.E., Ph.D.
Geotechnical Engineer
U.S. Army Corps of Engineers, Huntington, West Virginia

A major goal of each US Army Corps of Engineers (USACE) project is to capture lessons learned and communicate them forward from project to project. This permits sharing of knowledge and experiences nationwide and helps improve the USACE contractual methodologies, reducing overall costs, and improving designs. An example of this is the evolution of seepage barrier wall contracts. From the first Wolf Creek Dam cutoff wall in the 1970's to the more recent Bolivar and East Branch Dam cutoff walls, documentation and sharing of lessons learned have increased the efficiency and effectiveness of barrier wall designs and contract specifications. The evolution process includes updates in contract philosophy, methods for verifying that construction meets design requirements, and inclusion of effective data management solutions for use during both construction and long-term documentation of the project.

11:50 am Lunch
1:00 pm Lessons from the Bingham Canyon Slide – Monitoring Methods

Brad Ross, Ph.D.
Professor of Practice and Co-Director
Lowell Institute of Mineral Resources, University of Arizona, Tucson, Arizona

On April 10, 2013, the Rio Tinto Kennecott's Bingham Canyon Mine experienced the largest highwall failure in mining history, when 144 million tons of material exploded out of the highwall and flowed to the bottom of the gigantic pit. Most who saw the photos after this massive event believed that the historic mine was finished and would never operate again. The events will be reviewed and the details of how the mine suffered incredible damage to the face of the pit and equipment, but were able to keep people safe, will be presented. The geotechnical monitoring used to predict the failure will be discussed, as well as how this landslide was different from any other in the 107 year history of the mine. Finally, some of the lessons learned on how the mine used leadership, innovation, and teamwork to recover and return to full production will be explained.

1:40 pm Improving Roadway Performance by Wicking Geotextile to Reduce Soil Moisture

Jie Han, P.E., Ph.D.
Professor, Civil, Environmental & Architectural Engineering
University of Kansas, Lawrence, Kansas

It is well recognized that water has detrimental effects on roadway performance due to the increase of soil weight, expansion-shrinkage, and freeze-thaw potential and the reduction of soil strength and modulus. Reduction of soil moisture can improve the roadway performance, often through drainage and dewatering, which require saturation of soil and hydraulic gradient. However, soil in roadways may not always be saturated. Even under partially saturated conditions, soil may have a high moisture content that is still problematic to roadway performance. A new and innovative geotextile product (named the wicking geotextile) has deep-groove fibers with large surface areas that can generate capillary or suction force to suck water into the fibers when they are in contact. The sucked water can be transported to the exposed surface of the geotextile where it can evaporate into air. This process continues until the suction in the fibers is equal to that in the soil. This presentation will discuss the detrimental effects of water to roadway performance, explain the mechanisms of wicking geotextile, present laboratory investigation and results of the wicking geotextile put through various tests, discuss field verification of the wicking geotextile to reduce soil moisture and eliminate freeze-thaw problems in unpaved and asphalt paved roads and discuss the procedures developed for designing asphalt paved roads using the wicking geotextile.

2:20 pm Break
2:50 pm

Case Histories

Concurrent Session 1A:

Instrumentation and Monitoring of JEF-152 Landslide in Ohio

Mohammad Yamin
Assistant Professor of Civil Engineering
Minnesota State University, Mankato

A case study of a slope stabilization project using a single row of rock socketed drilled shafts is presented here. The design method, instrumentation program, and slope/drilled shafts monitoring results are presented. The slope is instrumented with inclinometers to obtain soil movement, piezometers to observe the ground water table (GWT) line, and soil pressure cells to measure earth pressures in different zones. Two drilled shafts are instrumented with an inclinometer in each one to measure the shaft deflection. Furthermore, strain gages and pressure cells were also embedded in the drilled shafts to measure the strain in the longitudinal reinforcement and contact earth pressures at the contact interface between the shaft and the soil. Observations and conclusions regarding the effectiveness of drilled shafts in stabilizing the reconstructed roadway embankment are presented.

Concurrent Session 1B:

Geotechnical Performance Monitoring of Foundations and Rock Slopes on the US 53 Realignment in Virginia, MN

Derrick Dasenbrock, P.E.
Geomechanics/LRFD Engineer
MnDOT, Maplewood, MN

Two new bridges and 3.2 miles of new roadway were constructed as part of a high-profile project to relocate US highway 53 in Virginia, MN. The construction work included several interrelated aspects of short-term and long-term geotechnical foundation and rock slope instrumentation, performance monitoring, and evaluation. Several pre-design pile load tests were conducted on drilled pipe piles, for a large 3-span bridge crossing the Rouchleau Mine Pit, to help characterize pile behavior prior to the bridge foundation final design. Strain sensors were installed in two of the 18 piles supporting the west pier of the bridge. A small bridge constructed for local access to MN highway 135 was constructed on spread footings; these foundations were monitored for settlement during construction. In addition, as part of both the short-term construction monitoring and the overall corridor long-term maintenance plan, four rock slopes were instrumented with ShapeAccelArrays and optical prisms to monitor their behavior over time. The geotechnical character of the site, the new bridge and roadway assets, the geologic and long-term site risks, and challenges and benefits associated with the geotechnical performance monitoring of the foundations and slopes will be discussed.

Concurrent Session 1C:

Mesa Verde National Park, Spruce Tree House Alcove Local Arch Analysis

Lee Petersen, P.E., Ph.D.
Principal Engineer
Itasca Consulting Group, Minneapolis, MN

Mesa Verde National Park, located in southwestern Colorado, is the site of Spruce Tree House, which is the third largest and best-preserved cliff dwelling in the Park. The Spruce Tree House cliff dwelling was constructed about 800 years ago, in a naturally-formed alcove about 216 ft wide by 89 ft deep. The alcove is located across a deep, narrow canyon from the Park museum, and is a very popular destination. The nose of the alcove contains a thin arch delineated by a persistent curved crack, which extends about 270 ft north from above the south end of the alcove. The crack is up to several feet wide, and the arch cross section is roughly 10 ft thick by 20 ft high. A 1960s investigation led to a stabilization program that included rockbolts and a thorough cleaning and grouting of the crack. Recently, rockfalls from the arch and adjacent rock surfaces demonstrated the need for a new assessment of arch stability and stabilization. The presentation will describe the arch geometry, site characterization, statics-based stability assessment, development and calibration of a 3DEC model, and use of the model to develop a stabilization plan.


3:20 pm Concurrent Session 2A:

US Highway 14 Embankment Over Soft Soils – Success with Ground Improvement and Modern Instrumentation

Richard Lamb, P.E.
Foundations Engineer
MnDOT, Maplewood, MN

In 2016, MnDOT constructed a new segment of Westbound US Highway 14 near Nicollet, MN over a deep layer of highly compressible soils using a combination of wick drains, surcharge fills and extended waiting periods. During design, several ground improvement methods were presented as feasible options to mitigate the estimated 3 ft of settlement expected from the placement of 7-10 ft embankment fills. These options included excavation and replacement, lightweight fill, column supported embankment, and wick drains with soil surcharge and waiting periods. After reviewing each option, the District chose to proceed with the wick drain-surcharge option because it represented a good balance of low cost and acceptable risk and fit well with the proposed construction schedule. To help reduce long term settlement risk, a robust geotechnical instrumentation monitoring program was designed to control the rate of fill placement and measure the magnitude and velocity of vertical displacements. The instrumentation included a precise horizontal inclinometer (MEMS ShapeAccelArray) and several nests of vibrating wire piezometers all connected to an automated data collection system with real-time online data posting. A summary of the project challenges, ground improvement decision process, and details on the instrumentation monitoring and results will be presented.

Concurrent Session 2B:

Shallow Bridge Foundations on Large Rock Fill

Brent Theroux, P.E.
Senior Geotechnical Engineer
Barr Engineering, Minneapolis, MN

As part of the recent TH 53 realignment through Virginia, Minnesota, which includes a new 1133-feet long bridge crossing the Rouchleau Mine Pit, the old interchange connecting TH 135 to TH 53 was replaced with a new interchange. The new interchange would include approach embankments consisting of up to 36 feet of new fill separated by a two span bridge. Subsurface conditions beneath the embankments and substructures consisted of soft glacial till overlying shallow bedrock of the Pokegama formation. The roadway design included extensive soil correction of the soft clay till. Supporting the bridge substructures on piles or other deep foundations was disadvantageous due to potential large drag loads induced on the piles and anticipated challenges achieving suitable pile penetration into the Pokegama. The final design consisted of supporting the foundations on shallow spread footings. Because shallow foundations are not traditionally used to support MnDOT bridges, the foundation design included an automated instrumentation and monitoring program to track settlement of the spread footings from the beginning through the end of construction and afterward. Prior to construction, the contractor proposed using large excavated blast rock and mine waste rock for the compacted structural fill beneath the bridge foundations. Use of the excavated rock fill was contingent on successfully performing field test sections to demonstrate acceptable compaction of the material. A detailed description of the testing will be provided.

Concurrent Session 2C:

U.S. Bank Stadium Earth Retention and Other Underground Construction

Doug Hardin, P.E.
Senior Design & Construction Manager
Schnabel Foundation Company, Cary, Illinois

The earth retention systems for the U.S. Bank Stadium, home of the Minnesota Vikings, were built during the winter of 2013-2014, the coldest in the Twin Cities in 35 years with an average temperature below 10°F. Schnabel Foundation Company designed and constructed permanent tieback soldier pile and wood lagging support systems up to 40 feet high to resist permanent lateral loads along the stadium below grade walls. Additionally, Schnabel installed temporary tieback soldier pile and wood lagging walls, rock anchor tie-downs for the stadium foundations, tiebacks for other temporary excavation support systems and drilled piers for a tower crane foundation between December 2013 and May 2014. The project's ground conditions created difficult challenges that required specialized equipment and tooling. The design and construction of the earth retention systems along with other site challenges and teamwork required to complete the work within the project's aggressive schedule will be presented.


3:50 pm

Concurrent Session 3A:

Behavior of Soft Lake Marl at a Preload Test Site in the Great Lakes Region

Mark Muszynski, P.E., Ph.D.
Assistant Professor, Civil Engineering
Gonzaga University, Spokane, Washington

Lake marl is found throughout the world, often in post-glaciated regions where inland lakes or low-lying areas and calcium-rich conditions exist. This rock has traditionally posed challenges for foundation support. The subject of this study is a residential development in Northern Michigan. The project required raising the existing site grade by up to 2.7 m (9 feet). Soil borings performed on the site revealed soft lake marl underlain by a more competent clayey silt deposit, followed by medium dense sand. Specimens within the lake marl stratum were recovered for consolidation and other index testing. Consolidation testing confirmed known compressibility characteristics. A variety of methods used to obtain preconsolidation pressure and coefficient of consolidation from the laboratory incremental loading oedometer consolidation tests are compared as part of this study. A field preloading test was conducted on the site after laboratory testing and prior to raising the site grade. The preload test was conducted for sufficient duration to allow observation of primary and secondary settlement behavior of the marl deposit. Settlement and porewater pressure observations taken during the field preload tests were evaluated using various methods and compared to predictions based on the laboratory testing program. Practical discussion of engineered fill placement in stages is offered, along with other observations concerning the special sampling and testing considerations of lake marl.

Concurrent Session 3B:

Construction Projects Requiring Rock Socket Construction in Precambrian Age Rock

Stanley Vitton, P.E., Ph. D.
Associate Professor, Civil and Environmental Engineering
Michigan Technological University, Houghton, Michigan

Two construction projects were completed in the western portion of Michigan's Upper Peninsula in Precambrian rock that contained some fractures, but was essentially hard and competent. The first project involved a bridge foundation on US-2 near Loretto, MI constructed in the Negaunee Iron Formation. The second project involved reconstruction of a bridge located on state highway M-28 near Covington, MI. Both projects involved rock socket construction. The lessons learned in the two projects are as follows: first, rock testing should be conducted on rock core when constructing rock sockets to better determine the required drilling technique, especially when constructing rock sockets in Precambrian age rock. Second, rock types can have a very wide range of intact strengths. Finally, various reasons can be given for why a rock core can become highly fractured during drilling with the most likely cause being poor drilling techniques. Another possibility, however, is the potential for residual stresses causing premature fracturing similar to rock disking. The presentation provides numerical simulation calculation to possibly explain high fracture rates in hard, brittle rock under lower stresses during drilling if residual stresses do in fact exist. Further, a hypothesis is provided for the possible existence of residual stresses in metaphoric rock.

Concurrent Session 3C:

Permanent Soil Nail Retaining Wall, University of Minnesota Combined Heat and Power Plant, Minneapolis, Minnesota

Chad Underwood, P.E.
Principal Engineer
Engineering Partners International, Richfield, MN

The University of Minnesota recently completed a major upgrade to the Old Main Heating Plant, now referred to as the Combined Heat and Power Plant (CHPP), located on the East Bank of the Minneapolis campus. The project involved the removal of existing coal-fired boilers, and the installation of new dual fuel Combustion Turbine and Heat Recovery System Generators. In addition, the Incinerator Building was demolished, and a new access road was constructed into the site. To accommodate the large grade change that came along with this, the project design team originally planned to construct a cast-in- place concrete retaining wall anchored to bedrock, which was anticipated to be present at relatively shallow depths over much of the wall alignment. Due to deeper bedrock than expected, a temporary earth retention system would be required to allow excavation to the bottom of retaining wall footing elevation. Following completion of supplemental geotechnical exploration, the cast-in- place retaining wall was redesigned as a soil nail wall. The use of a soil nail wall allowed the retaining wall to be constructed in a top-down manner, eliminating the need for a separate temporary earth retention system. The challenges associated with constructing a permanent soil nail wall in a complex geologic setting, under a tight timeline, and with special architectural requirements due to high visibility of the wall will be discussed.


4:15 pm Adjournment
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