Bauer company introduced for the first time in the region the underground pedestrian crossing tunnels. It started first in UAE in 2001 where 22 tunnel were constructed. Thus after this technology was used in Qatar since 2013. The process is comprising by means of soil stabilization around the proposed tunnel with the aid of installing injection pipes using very precise directional drilling technique and injecting a dual mix consisting of sodiom silicate solution and ultrafine cement. The stabilized soil then could be excavated following the size and shape of the tunnel horizontally in sections without stopage of the running traffic above the tunnel area.

Types of Construction Method

The pipe roofing consists of an arch made of steel casings with a spacing center to center as per drilling. They will be placed on a circle. Depth of arch vault varies at each location. Minimum ground cover above pipes needs to be considered to avoid clashes with utilities embedded in ground.

The Bauer tunneling technique is a trenchless technique which allows tunnel excavation under heavy traffic load without closing or diverting the traffic flow. Horizontal directional drilling and grouting is carried out from the starting on/or receiving shafts in a completely digitally controlled manner. Once the injection pipes are installed into the directionally drilled holes and the combined grout scheme executed (UFC and silicate), allowing for a curing time of minimum seven days after grouting, the sectional excavation (2 m max.) of the tunnel can proceed followed by the shotcrete layer, water tight membrane, concrete structure and finishing works.