UndergroundMechanical Application of Shotcrete in Underground Construction
Position Statement #4 ASA Underground Committee
Read MoreThe manual hand application of shotcrete began over 100 years ago and continues today in a wide range of applications and projects. To provide a proper distance of the shotcrete nozzle tip to the underground surface wall, surface receiving shotcrete or ‘substrate,’ the hand application of shotcrete in larger diameter underground structures required the nozzlemen to operate from a man-lift or similar equipment. Working from elevated platforms and the close proximity of the nozzleman to the substrate added safety challenges to projects. Thus, as more underground projects started to use the wetmix shotcrete process, spraying shotcrete with mechanical arms began to address these safety concerns.
UndergroundSite-Specific Mine Site Safety in North America
Mike Ballou
Read MoreShow me a person who tells you that safety on a mine site is just plain common sense, and I’ll show you someone who doesn’t understand mine safety completely. Mine safety is not simply common sense. It is that, and a whole lot more. Most mines have their own set of mine-specific regulations and rules. Nearly all mines, in Canada, the USA, and Mexico, are required by law, to follow government-mandated requirements such as U.S. Department of Labor- Mining Health & Safety Administration (MSHA) and/or the Occupational Safety & Health Administration (OSHA). Canada and Mexico have their government agencies governing mining as well. Even with strict government regulations, most mines have safety regulations specific to each individual mine. Anyone who desires to visit a mine site needs to accept one thing- whatever the rules and regulations are for a particular mine- these regulations are serious business and are meant to be enforced.
UndergroundSafety in Shotcrete Application in Underground Construction
Raul Bracamontes
Read MoreBecause of its durability, strength, and flexibility in application, shotcrete is often used for the construction and stabilization of tunnels and other underground structures. The fact that tunneling involves general construction risks as well as tunnel specific environmental risks, makes this type of application potentially quite dangerous, and must be treated with caution. Risks cannot be eliminated, but we can implement measures to lower the risk.
UndergroundGeneralASA Real-Time In-Situ Article
Benny Chen, Christian Reich, Peter Ayres, and Nicholas Carter
Read MoreConstruction of sprayed concrete lining (SCL) ground support across the world utilizes the construct, verify and rework cycle. This methodology typically requires survey verification of the as-built result against design for each stage of the ground support installation. However, processing and analyzing the measurement data
RepairArchitecturalUndergroundStructuralGeneralShotcrete Incorporated into ACI 318-19 Building Code
Charles Hanskat, Terence C. Holland, and Bruce A. Suprenant
Read MoreSince the shotcrete process originated well over 100 years ago, improvements in materials, equipment, and placement techniques have enabled it to become a well-proven method for structural concrete placement. The efficiency and flexibility of shotcrete have been used to great advantage in sizable structural projects, as
UndergroundGeneralPerformance of Synthetic Sheet Waterproofing Membranes Sprayed with Steel Fiber-Reinforced Shotcrete
Antoine Gagnon, Marc Jolin, and Jean-Daniel Lemay
Read MoreThe recent Position Statement #2, “Spraying Shotcrete on Synthetic Sheet Waterproofing Membranes,” published by the ASA Underground Committee, pointed out many aspects critical to successful performance and raised some potential issues affecting the placement.1 In the position statement, specific techniques are presented to prevent problems
UndergroundGeneralFiber-Reinforced Shotcrete Applications and Testing Overview
Antoine Gagnon and William (Bill) Geers
Read MoreThe 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
UndergroundMaryland Purple Line Plymouth Tunnel
Nick Tabor and Norbert Fuegenschuh
Read MoreThe 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
RepairUndergroundQueens Midtown Tunnel Rehabilitation
Ashley Cruz
Read MoreThe Queens Midtown Tunnel (QMT) is a twin-tube, tolled, four-lane highway that serves over 90,000 vehicles each day.
RepairUndergroundTiber Creek Sewer Rehabilitation
John Becker and Randle Emmrich
Read MoreAs 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.