Underground Gallery

1. In order to be able to excavate a gallery section to the planned width and height, the first step is to install the gallery ceiling. This is achieved by means of small local earthworks combined with the driving of metal sheet piles.

2. Once all the sheet piles are in place, the top beam of the next frame is installed. This is held in place by a system of levers supported by the frames already in place.

3. The entire section can then be excavated, with side (and front) shoring in place. The earth is loaded manually by the workers and removed to the gallery entrance using wheelbarrows.

4. The remainder of the frame (2 legs + lower base) is then placed. If required, concrete blocking can be placed between the lower beams of the various frames to give the whole structure greater stability.

 Repeat the above steps until the desired gallery length is reached.

• Can be applied to all types of soil as long as they are dry or flattened.

• Low risk for buried installations, since you can see what you're doing.

• Very small site footprint (a gallery can be built from a 1.50 m x 1.50 m shaft)

• No need for heavy machinery, so can be used in hard-to-reach locations or near sensitive elements (railroad or streetcar tracks in service, factories in operation, etc.).

• No vibration ;

• Soil extraction necessary ;

• Limited noise production ;

• Stable, dry and flat work platform is required, however the platform can be small and possibly difficult to access.