Underground Portal

UndergroundRelease of New ASTM Round Panel Test

Stefan Bernard

Following a 3-year development period, a new test for post-crack performance assessment of fiber-reinforced shotcrete (FRS) and fiber-reinforced concrete (FRC) based on round panels was passed by ASTM Committee C 09 in June 2002. The standard test method, known as C 1550-02, œStandard Test Method

UndergroundInternationalShotcreting in Australian Underground Mines: A Decade of Rapid Improvement

Matthew Clements

Over the last decade, dramatic improvements in spraying technology have allowed shot-crete to become the first-choice ground support in many underground mines in Australia. Before 1994, only a very small amount of dry spray shotcrete was used. Since then, the increased use of wet-mix fiber-reinforced

UndergroundStructuralShotcrete for Ground Support: Current Practices in Western Canada

Cesar Chan, Roland Here, and Dudley R. Morgan

Historically, in Western Canada, the stabilization of rock slopes and construction of excavations have been achieved using methods such as soldier piles and lagging or construction of cast-in-place concrete retaining walls. In the case of reinforced cast-in-place concrete, there is a requirement for erection of

UndergroundShotcrete in Fires: Effects of Fibers on Explosive Spalling

Peter C. Tatnall

In those of us in the concrete industry, the events over the last year have caused many of us to focus on the effects of blasts and fire on concrete structures. Information on the effects of fire on normal strength concrete (NSC) less than 7000

RepairUndergroundThe Art of Tunnel Rehabilitation with Shotcrete

Harvey Parker, Paul Godlewski, and Roberto Guardia

The art of rehabilitation of tunnels has flourished and developed significantly over the last couple of decades. Several hundred railroad, highway, and conveyance tunnels have been successfully rehabilitated, converted, and/or enlarged. Much of this development can be attributed to the successful use of steel fiber-reinforced

UndergroundStructuralSoil and Rock Slope Stabilization Using Fiber-Reinforced Shotcrete in North America

Mike Ballou and Matt Niermann

UndergroundStructuralDesign Guidelines for the Use of FIber-Reinforced Shotcrete in Ground Support

F. Papworth

Developments in Shotcrete in Hobart, Tasmania, Australia in April 2001. One of the outstanding papers presented at the Conference was a paper by Grant, Ratcliffe and Papworth on œDesign Guidelines for the use of SFRS in Ground Support. Frank Papworth was asked to submit an

UndergroundStructuralDetermination of Early-Age Compressive Strength of Shotcrete

Roland Here and Dudley R. Morgan

Tere has long been a need for a reliable, simple-to-use means of determining the early-age rate of strength gain in shotcrete.During approximately the first 24 hours after shotcrete has been placed, its compressive strength is typically too low to measure using standard core-extraction and testing

UndergroundShotcrete for Ground Support: Current Practices in Western Canada

Cesar Chan, Roland Here, and Dudley R. Morgan

Each ground-support project is unique and will likely have its own design and performance re-quirements. Performance requirements for shotcrete can generally be divided into two groups: fresh state parameters and hardened state parameters. The following briefly elaborates on the variables included in each of these

UndergroundWelcome to Underground Atlanta

Charles M. Brown

We are standing in the very bowels of the City of Atlanta. This isn™t the trendy œUnderground Atlanta of rock-till-you-drop nightclub fame. The millions of busy Atlanta citizens above us today don™t have any idea that we are down here. All they care about is