Application spotlight: TUNNELS

Shotcrete is a concrete coating technique used in construction due to its ability to be placed and compacted at the same time, as well as acting as a stabilization layer in applications such as slopes and tunnels. The main benefit of using shotcrete in a tunnel application, besides the stabilization, would be to prevent falling rock and groundwater from leaking onto the roadway while also providing support and protection to drainage systems installed in various locations around the tunnel.

Before placing the shotcrete in the crown of the tunnel, contractors typically install a primary drainage layer to help capture and move hill water from the top of the crown to the sidewalls, thus minimizing the impact of hydrostatic pressure build up and leaking water which can cause the excavation to become unstable and collapse.

AWD manufactures SITEDRAIN Single-Sided Sheet Drain, which is typically used for the drainage layer in tunnel applications. It is preferred for this application due to its lightweight characteristics, which allows it to be hung easily and secured with numerous different methods. The thickness of the product is also preferred over conventional drainage methods. AWD recommends using the SITEDRAIN Sheet Drain 180 Series, due to its high compressive strength, which is useful in shotcrete spray applications.