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Friday, February 22, 2019

7:30 am Registration and Continental Breakfast
8:15 am Welcome
  Distinguished Representative
College of Science and Engineering
University of Minnesota
8:25 am Kersten Lecture
Ground Deformation Effects on Subsurface Pipelines and Infrastructure Systems

Thomas O’Rourke, Dist. M. ASCE, NAE, FREng
Civil and Environmental Engineering
Cornell University, Ithaca, New York

There are tens of millions of km of pipelines worldwide used in water supplies, gas and liquid fuel delivery systems, electric power networks, and wastewater conveyance facilities. An overview of these critical infrastructure assets is provided. Soil-structure interaction affecting pipeline and underground conduit response to externally imposed ground deformation is examined, starting with stress transfer from soil to the circular surface of the pipe. Various models for soil-pipeline interaction are described, and a methodology is proposed for evaluating soil-pipeline interaction in granular soils for any direction of pipe movement at any depth. Suction-enhanced soil reaction to relative soil-pipe movement is discussed. Guidance is provided regarding soil-pipeline interaction modeling in which the pipeline is represented as a beam vs a three-dimensional shell. Large-scale laboratory testing and numerical modeling for the next generation hazard-resilient pipelines are described, and innovative ways of accommodating ground deformation are illustrated. Water supply system response to widespread liquefaction-induced ground deformation during the Canterbury Earthquake Sequence in New Zealand is evaluated with high density LiDAR and GIS analyses, and a methodology is presented for estimating pipeline damage as the combined response to liquefaction-induced differential settlement and lateral ground strain.

9:20 am Slope Instabilities Associated with Debris Flows

Kimberly Hill, PhD
Civil, Environmental, and Geo- Engineering
University of Minnesota, Twin Cities

When a debris flow – a large flow of boulders, gravels, sands, and mud – moves down a slope, it can entrain materials many times the initial mass of the flow. The amount of material entrained influences the potential damage inflicted on communities in its path, making it an important parameter for hazard mitigation models. We present experiments in a novel laboratory flume to study particle-scale controls on entrainment and deposition due to debris flows. We control particle size distribution and fluid content in the flow itself and in an erodible bed over which the mixture flows, and monitor pressures, particle velocities, and average and fluctuating stresses. While a common technique for including entrainment rates in hazard mitigation models involves average stress in the flow, we find that this is not typically the case. Rather, the entrainment rates are strongly influenced by particle size distribution, which controls the magnitude of stress fluctuations and spontaneous sorting of the flowing particles in the shear flow. We show how this can be incorporated into a better understanding of field-scale measurements and, ultimately, better hazard prediction models.

10:00 am Break
10:30 am SHANSEP Method to Assess Driven Pile Side Resistance in Cohesive Soils

Steve Saye, PE, PhD
Senior Geotechnical Engineer
Kiewit Engineering Group Inc, Omaha, NE

The adaptation of the stress history and normalized soil engineering properties, SHANSEP, equation to relate the soil over consolidation ratio, OCR, to the normalized side adhesion in cohesive soils described by Saye et al. (2013) provides an efficient approach to assess the capacity of driven closed-end and open-end pipe piles in cohesive soils. The assessment of OCR based on screened oedometer tests and unconsolidated-undrained compression tests is thought to provide an assessment of soil properties with a minimum of sample disturbance effects, especially for low OCR soils. This approach is updated with the addition of a construction influence factor, CI, to assess pile installation procedures that are thought to damage the pile side resistance, including re-driving after set up, long installation time, and use of a vibratory hammer.

11:10 am Regional LRFD Calibration of Drilled Shafts

Jeramy Ashlock, PhD
Civil, Construction, and Environmental Engineering
Iowa State University, Ames, Iowa

Following successful implementation of Load and Resistance Factor Design (LRFD) calibration for driven piles in Iowa, similar LRFD calibration studies for drilled shafts have been sponsored by the Iowa Department of Transportation. Through this effort, the drilled shaft load test database DSHAFT has been continually updated with new load tests and associated site characterization data. Several issues that make regional calibration of resistance factors for drilled shafts more challenging than for driven piles will be discussed. To eliminate the need to extrapolate typical load test data to determine the ultimate unit side shear, two top-down and three pullout tests were performed on reduced-diameter shafts. Results of the load tests and LRFD calibrations will be presented.

11:50 am Lunch
1:00 pm Seismic Landslide Assessments: Bridging the Gap between Engineers and Earth Scientists

Ellen Rathje, PE, PhD
Civil, Architectural, and Environmental Engineering
University of Texas, Austin, Texas

Earthquake-induced landslides represent a significant seismic hazard, as evidenced by recent earthquakes in Kaikoura (New Zealand) and Gorkha (Nepal) and proper planning/mitigation requires accurate evaluation of the potential for landslides. Engineers often tackle this problem through a detailed evaluation of individual slopes and more recently have introduced performance-based engineering (PBE) concepts into the analysis. Recognizing the compounding effects of multiple landslides across an area, earth scientists often evaluate landslides at a regional scale. This approach sacrifices details but provides a broader assessment of the impacts of earthquake-induced landslides. This presentation will describe the integration of performance-based engineering concepts into regional-scale landslide assessments. The basic PBE framework for seismic landslides will be introduced along with the modifications required to apply it at a regional scale. The application of the approach for a seismic landslide hazard map will be presented. The use of seismic landslide inventories to validate regional landslide assessments will be discussed, along with advancements in developing seismic landslide inventories using remote sensing techniques.

1:40 pm Landslide Mitigation using Anchored Shear Piles

Thomas Westover, PE
Associate Engineer
Cornforth Consulting, Portland, Oregon

Anchored shear piles (ASP) can be used to develop full-depth restraint of large landslide masses with limited post-construction deformation. This presentation highlights a case study for landslide mitigation in Multnomah County, Oregon. The original bridge was built in 1925 at the site of an ancient landslide located along the west bank of the Willamette River. The landslide, approximately 800 feet long, 500 feet wide, and 50 feet deep, had moved in excess of three feet toward the river channel during the old bridge’s 90-year history, which caused severe buckling and cracking of the bridge deck and abutment piers. The landslide movement was mitigated using an ASP system to facilitate construction of a three-span arch bridge. An ASP system can provide full-depth resisting force to a landslide, without the risk and right-of-way impacts of large open-cut excavations and buttressing. An innovative “re-stressing” program, tailored to the instrumented performance of the system during the four-year construction period, was implemented by using existing elements to add load into the system to meet design and seismic deformation criteria.

2:20 pm Break
2:50 pm

Case Histories

Concurrent Session 1A:

Building a Causeway through a Swamp: Column Supported Embankment for TH-169

Alex Potter-Weight, PE
Regional Design Manager
Menard Group, Chicago, Illinois

To replace an aging bridge carrying traffic on Trunk Highway 169 over Nine Mile Creek and the surrounding watershed in Hopkins, MN, the MnDOT applied a design-build approach to allow the project to be completed on an accelerated timeline. The bridge was replaced by a causeway formed by 3000-foot long MSE walls on both sides, with a 500-year flood elevation approximately halfway up the wall. The walls and the retained fill between them required ground improvement prior to construction in the form of a column supported embankment (CSE) system. As part of the project, a robust instrumentation program was also installed to monitor the performance of the causeway in real-time before and after construction. The columns for the CSE consisted of rigid inclusions, which are displacement-drilled grouted columns, and the system included a geosynthetic-reinforced load transfer platform to transmit the embankment stresses into the columns. The soft, organic, and variable nature of the wetland soils caused numerous challenges to the CSE design and construction.

Concurrent Session 1B:

Wabasha Street Rock Slide Assessment

Ryan Peterson, PE
Senior Engineer
Itasca Consulting Group, Minneapolis, MN

A rock slide blocked Wabasha Street in Saint Paul, MN in late April 2018. A Platteville limestone block weighing approximately 384,000 lb toppled off the bluff, broke into pieces, slid down the slope, overtopped a concrete wall, and blocked the west sidewalk and lanes of Wabasha Street. The bluff consists of five geologic layers, from top down: soil, weathered Platteville limestone, hard Platteville limestone, Glenwood shale, and St. Peter sandstone. The block that toppled was from the hard limestone layer; adjacent and overlying soil and weathered limestone were also part of the slide. Itasca Consulting Group conducted a thorough assessment of the cause of the rock slide; assessed the immediate and long-term threats posed by the rock slide and remaining materials; developed remedial measures for review by the City, and ultimately prepared construction plans.


3:20 pm Concurrent Session 2A:

Large Diameter Drilled Shafts on the Highway 63 Mississippi River Bridge

Nathan Iverson, PE
Chief Geotechnical Engineer
Veit & Company, Rodgers, MN

The new Highway 63 Bridge project replaced the old Eisenhower Bridge that had been deemed “fracture critical.” The bridge design included two large river piers supported on 9 and 10 ft diameter drilled shafts bearing 13.5 feet into bedrock up to 90 feet below river elevation. Pier 2 is located on the Wisconsin side and was drilled from a barge, while Pier 1 is located on the Minnesota side and accessed via a small access road alongside an active railroad track. The case study details the mass concrete performance, self-consolidating concrete mix performance, concrete placement techniques, thermal modeling, thermal integrity results and challenges associated with the access and construction of the foundations for the new bridge.

Concurrent Session 2B:

Stabilization of WAS-7 Landslide Using a Single Row of Drilled Shafts

Mohammad M. Yamin, PE, PhD
Civil Engineering
Minnesota State University, Mankato, MN

The site description, subsurface profile, slope stability analysis, instrumentation, and monitoring results of a stabilized slope will be presented. The slope was 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 contained inclinometers 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 will be discussed


3:50 pm

Concurrent Session 3A:

Design and Construction of Deep Foundation Elements in Decomposed Bedrock Conditions

Ryan Drury, PE
Associate Principal, Project Engineer
Braun Intertec Corporation, Minneapolis, MN

During field exploration and geotechnical evaluation for a new 13-story building in Rochester, Minnesota, Braun Intertec encountered extremely variable and decomposed bedrock conditions approximately 30 feet below ground surface, corresponding to the unconformity between the St. Peter Sandstone and Shakopee Dolostone. The decomposed conditions included layers of dolostone between soil-filled cavities and areas of bedrock decomposed to a soil-like consistency. Braun Intertec evaluated several foundations methods and worked with the owner and design team to develop the appropriate method for the site conditions. We will discuss the risk tolerance and design approaches for the project and the various foundation elements used to support the structures (spread footings, drilled shafts, and micropiles).

Concurrent Session 3B:

Geotechnical Monitoring: A Key Element of the Creative and Effective Landslide Remediation Solutions for Minnesota Highway 210 in Jay Cooke State Park

Derrick Dasenbrock, PE
Geotechnical Engineer
MnDOT, Maplewood, MN

In June 2012, more than ten inches of rain fell in two days on parts of northeastern Minnesota causing slope failures in the greater Duluth area. Minnesota Highway 210, through Jay Cooke State Park, was significantly damaged in many locations by landslides and in other locations completely destroyed by wash-outs. Beginning in 2015, MnDOT repaired and stabilized 74 discrete landslide sites totaling more than 28 acres of steep slopes along approximately 3.5 miles of the highway using a design-build contracting framework. The performance-based project allowed the contractor to use a large variety of site-specific geotechnical and structural designs to effectively stabilize the roadway and slopes. A robust monitoring program was used to evaluate the performance of each repair. The paper focuses on the variety of design solutions and the associated challenges and benefits of multi-year continuous performance evaluation for landslide stabilization.


4:15 pm Adjournment
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