3 ms·

I'm not a construction engineer by any means but there are a few things I can't warp my head around. Why are they using robots at all? It seems like a pretty bi

I'm not a construction engineer by any means but there are a few things I can't warp my head around. Why are they using robots at all? It seems like a pretty big hassle to construct those robots that deposit large amounts of material with high pressure through a hole that needs to be drilled in their own tunnel. Why not excavate the volume between the small boring holes with the same technique they used to create them in the first place? Bore those smaller holes with equal spacing, fill them with concrete, and then repeat for the volume in between. What about steel? Not needed for in tunnels?

jaclaz 4y ago
When you tunnel in very loose material, it is a long established technique to drill steel reinforced micropiles (in jargon often called "umbrellas") like in this sketch: https://www.rodio.ch/rodio-geotechnik-ag/pipe-umbrella-rodio-geotechnik-ag.html https://www.rodio.ch/rodio-geotechnik-ag/pipe-umbrella-rodio... Typically these are no longer than 18 meters and have a 3 meters overlap, there are limits in the precision of the drilling and to allow the "next" umbrella to start at the right height/width holes need to have a slightly open angle. Even if it doesn't seem so to the casual viewer, drilling a (usually) 120-150 mm diameter hole 18 m long results in a non-straight hole due to the flexibility of the drilling rods and the possibility of deviations caused by the presence of different materials, it is not at all an "exact science" and there can be easily errors at the end of the 18 m hole of up to 50 cm or so. There are of course techniques that allow to drill much straighter holes using external casings, like the type that seem to be used in the video, but they are much more complex (and costly), and anyway the precision of these is far from being "high", in case of long holes.

jaclaz 4y ago

When you tunnel in very loose material, it is a long established technique to drill steel reinforced micropiles (in jargon often called "umbrellas") like in this sketch: https://www.rodio.ch/rodio-geotechnik-ag/pipe-umbrella-rodio-geotechnik-ag.html https://www.rodio.ch/rodio-geotechnik-ag/pipe-umbrella-rodio... Typically these are no longer than 18 meters and have a 3 meters overlap, there are limits in the precision of the drilling and to allow the "next" umbrella to start at the right height/width holes need to have a slightly open angle. Even if it doesn't seem so to the casual viewer, drilling a (usually) 120-150 mm diameter hole 18 m long results in a non-straight hole due to the flexibility of the drilling rods and the possibility of deviations caused by the presence of different materials, it is not at all an "exact science" and there can be easily errors at the end of the 18 m hole of up to 50 cm or so. There are of course techniques that allow to drill much straighter holes using external casings, like the type that seem to be used in the video, but they are much more complex (and costly), and anyway the precision of these is far from being "high", in case of long holes.