Article

UndergroundGeneralFiber-Reinforced Shotcrete Applications and Testing Overview

Antoine Gagnon and William (Bill) Geers

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The addition of fibers to concrete and mortars as reinforcement is not a new concept. The ancient Egyptians used straw to reinforce mud bricks for use in structures like the core walls of the pyramids. During the first century AD, the Romans incorporated horsehair fibers

Article

UndergroundMaryland Purple Line Plymouth Tunnel

Nick Tabor and Norbert Fuegenschuh

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The Plymouth Tunnel is a 1020 ft (311 m) sequential excavation method (SEM) tunnel located in Silver Spring, MD, that makes up a portion of the Maryland Transit Authority’s (MTA) Purple Line light rail connecting the existing metro lines around Washington, DC. The Purple Line

Article

RepairUndergroundQueens Midtown Tunnel Rehabilitation

Ashley Cruz

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The Queens Midtown Tunnel (QMT) is a twin-tube, tolled, four-lane highway that serves over 90,000 vehicles each day.

Article

RepairUndergroundTiber Creek Sewer Rehabilitation

John Becker and Randle Emmrich

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As part of the DC Clean Rivers Project ? Division 1 Main Pumping Station Diversions, the Tiber Creek trunk sewer was designated to receive a new structural liner in a 122 ft (37 m) section near the intersection of New Jersey Ave. and Tingey St.

Article

UndergroundFlood Control Channels Made with Shotcrete

Raúl Bracamontes

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Flooding is a temporary overflow of water onto land that is normally dry. Floods are the most common natural disaster in the United States.

Article

UndergroundStructuralStructural Modifications to Hydroelectric Turbine Draft Tube Ceiling

Shaun M. Radomski, Dudley R. (Rusty) Morgan, Lihe (John) Zhang, and David Graham

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The U.S. Army Corps of Engineers (USACE) is engaged in structural modifications to the reinforced concrete draft tube exits from the turbines in the Ice Harbor Lock and Dam located on the Snake River near Burbank, WA.

Article

UndergroundTunnel Shotcrete Lining for Hydroelectric Projects

Lihe (John) Zhang, Dudley R. (Rusty) Morgan, Serge Moalli, David Gagnon, and Danny Dugas

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In British Columbia (BC), Canada, the primary source of power supply is hydroelectricity.

Article

UndergroundOverhead Shooting against PVC Membrane

Frank E. Townsend III and Dennis Rubi

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Overhead shotcrete application against any substrate is challenging. Shooting against a polyvinyl chloride (PVC) membrane waterproofing system increases the difficulty and danger of the process.

Article

RepairUndergroundCreating a Foundation for Success: The Use of Lidar in Tunneling Projects

Carlos Gonzalez

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Shotcrete placement requires close attention to safety; when combined with the difficult working conditions of a tunnel, overhead placement requires even greaterawareness of potential hazards.

Article

UndergroundStructuralShotcrete Lining Innovations in the United States

Andy Thompson and Frank E. Townsend III

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Historically, the permanent concrete linings for underground structures have been installed using form-and-pour methods but the use of shotcrete or sprayed concrete for the structural linings is becoming increasingly more common.