Page 59

2014SprShotcreteEMag

Shotcrete FAQs and concrete. Shotcrete is a method of placing concrete and issue. Many soil nail wall systems incorporate a drainage ditch the same parameters used in concrete design apply to shotcrete at the top of the wall that catches the runoff and takes it to the placements. Many pools of this size are designed and built ends of the wall. Your concept of a catch basin and drain without expansion joints, but it is beyond the scope of our between the layers is not something we have seen in the past association to provide further guidance. and we are not qualified to express an opinion on this. We have seen systems with catch basins at the top of the wall and the Question: We are developing a tunnel. At the tunnel portal drains behind the initial layer of shotcrete requiring notching (entrance), we have high walls around the portal about 60 ft the subgrade. To answer your question, yes, a 6 in. (152 mm) (18 m) tall. They will have an inner structural shotcrete layer pipe can be fully encased in shotcrete between the layers. (4 in. 102 mm) and outer architectural shotcrete (12 in. Complete encasement of an embedment of this size needs an 305 mm). Between the structural shotcrete and rock/soil, we experienced shotcrete nozzleman with properly sized equip- have a drainage system to handle the groundwater. At the same ment, appropriate concrete mixture design, and a trained shot- time, we may have water at the top ground surface that will crete crew. The issue of appropriateness of the approach is drain from top to bottom of the wall. better answered by a licensed professional engineer familiar The owner didn’t want to make the water flow as a sheet over with soil nail systems or retaining walls, and shotcrete/concrete. the wall surface. We proposed an inlet and vertical 6 in. (152 mm) pipe drop from the top to bottom and band to a ditch at the Question: I am currently involved in the design of several long base of the wall. Can we locate the 6 in. (152 mm) pipe between retaining walls. One option under consideration is the use of the structural shotcrete and the architectural shotcrete? soil nails with shotcrete reinforced by welded wire fabric (WWF) and the other is the use of mechanically stabilized earth Answer: The Federal Highway Administration’s “Manual for (MSE) reinforcement (geogrids) with shotcrete reinforced by Design & Construction of Soil Nail Walls” should address this WWF. What is the best method (or product) to anchor each OnLine All ASA members and subscri- bers now have access to the electronic version of Shotcrete magazine. A link to this e-mag- azine is sent as an item in the “What’s in the Mix” e-newsletter. To ensure that you receive access to all future issues of the electronic version of the magazine, send your e-mail information to info@shotcrete.org. Shotcrete • Spring 2014 57


2014SprShotcreteEMag
To see the actual publication please follow the link above