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Brierley Presenting at North American Tunneling Conference


Brierley Associates tunneling specialists will be speaking at four technical sessions at NAT. And join us at the Women in Tunneling Breakfast, Monday, June 24th at 7 am.

To request the slides from these presentations, jump to the form at the bottom of this page.

Short Course: Critical Infrastructure Crossings

Jacked Box Design Solutions and Considerations and Case Study of the Empire State Trail Box Tunnel

Sunday, June 23 | 8 am – 4 pm

Authors: Jeremiah Jezerski, AJ McGinn

Post-tensioning has been used in bridge and building construction in the U.S. for more than 7 decades, with great success. For more than a decade, Brierley Associates has been adapting post-tensioning tools and methods to tunnel under critical transportation infrastructure with minimal disruption to the roadway or railroad above. The new approach pulls the boxes through the railroad embankment via post-tensioning tendons installed through the embankment and walls of the tunnels.

Learn more about these jacked box tunnel projects: Empire State Trail Box Tunnel and Twin Box Tunnels at Liberty University. about our innovative approach to constructing jacked box tunnels without disruption to the infrastructure above.

Case Study – Globeville Rail Crossing and Canopy Grouting

Sunday, June 23 | 11:30 am – 12 noon

Author: Bill Zietlow

Traversing under 19 railroad tracks, these twin 515-ft long 96-inch diameter tunnels posed many project challenges. Mixed-face conditions consisting of well-graded sand with gravel zones and lean clay were identified and there were indications of a buried pipe was within the tunnel alignment. During the first tunnel drive utilizing a microtunnel boring machine (MTBM) a zone of crushed and intact concrete made it difficult to maintain machine slurry pressure. Before the second drive, a grouted pipe canopy was installed from the receiving shaft to mitigate settlement effects. Additionally, consolidation grouting was performed from the ground surface into the crushed concrete pipe zone. Implementation of this solution was key to successfully complete the second tunnel.

TBM Rescue Shaft, Tunnel, and Relaunch in Karst Conditions

Monday, June 24 | 2:05 PM

Authors: Dan Swidrak, Affholder Construction and Bill Zietlow; Brierley Associates

Halfway through a 17,770-ft long stormwater tunnel, an 11-ft diameter TBM encountered a karst void below the Mississippi River in Missouri, resulting in significant inflow. It was decided that the TBM could not safely advance without external intervention. Bill and Dan review the methods used to advance the tunneling operation and successfully complete the tunnel.

Tunneling Through Reef Structures: Identification, Characterization, and Potential Impacts

Tuesday, June 25 | 11:50 AM

Authors: Ike Isaacson, Brierley Associates; Michael Miller, Citizens Energy Group; Jarek Trela, Illinois State Geological Survey

Despite reef structures being relatively common in carbonate rocks around the world, tunneling experience in reefs is extremely rare and the impacts and risks of tunneling are relatively unknown. A new reef was encountered during construction of the Lower Pogues Run Tunnel in Indianapolis, resulting in adverse impacts on construction. Analysis of investigation data and construction from this encounter provide insight into the identification and characterization of reefs along tunnel alignments as well as the potential impacts on construction for future tunneling within reef structures.

To Swell or Not to Swell – Design of Underground Structures in the Presence of Swelling Clays

Tuesday, June 25 | 2:05 PM

Author: Daniel Maine, Brierley Associates

Swelling clay soils have been problematic to many types of infrastructure in the United States. However, their impact on underground construction is often misunderstood. The use of swell pressures in design of initial tunnel and shaft support lacks proper guidance and is often mis-interpreted. This paper provides insight and guidance on how to implement a geotechnical investigation program to determine if swelling soil exists at a site and how it impacts the design of temporary support systems for underground projects.

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