Underground Vent Shaft detail

[sbw]

I'm hoping someone can help with a suggested resource for a small diameter (12"-36" diameter) vertical shaft design. Maximum depth of the shaft is about 30'. Shafts are for utility and air supply for and undergound tunnel in rock and are to be installed by drilling a hole, dropping in the liner, and grouting the void. The current layout has some shafts penetrating the tunnel liner (reinforced shotcrete) directly through the ceiling and others adjacent to the tunnel liner and tied in at the base. Based on prelim. check, the grouting pressures seem to control the liner. The ground is fractured sandstone. One of the concerns is moisture/condensation within the pipe. Also, if there's a better forum to post this in, please let me know.

Thanks in advance.

 

[miningman]

Check out Cubex.net in Winnipeg Canada with their V30 head. This will give you as small as 6 inch , thru 12-15 inches right up to 30 inches.

Other sources are any competant water well drilling outfit.

 

[cvg]

this sounds more like a drilled shaft for a bridge foundation, which is not typically done by a water well driller. check with the highway contractors to get a recommended driller or perhaps with a jacking / boring contractor.

 

[BigHarvey]

You could use a VDW ( Vor dem Wand ) drilling method. It is a drilling method using a cased continuous flight auger and a twin rotary head. You can see them on ABI gmbh site ( drilling rig manufacturer ) or Eurodrill ( twin rotary head manufacturer ). You can go up to 800 mm diameter to depths of 17 meters. You would just have to leave the steel casing in place after drilling. Does not work if soil or weathered rock is too hard for an auger.

 

[sbw]

Thank you all for your replies, but I think I've lead you astray. I know the drilling company and their methods for drilling the hole, so I'm o.k. there. My question is, for a commercial project utilizing the shaft for ventilation and utility (from surface) access, how should I detail the final liner of the shaft to ensure water and moisture are not an issue.

Thanks.

 

[miningman]

This now appears to be a dicussion on the practicalities of grouting. I cant supply definite recommendations without a lot more information but here are my immediate thoughts. You are proposing to break the shaft into an existing tunnel. How much water is flowing in the tunnel today, and how much of an increase in flow is acceptable??


In terms of grouting the annulus around your shaft lining, your drilling contractor should be able to provide recommendations but if you arent at least somewhat familiar with grouting techniques, you could very easily end up with an unsatisfactory project.

What is the level of the local water table in the sandstone?? How permeable is the sandstone?? What pressures do you intend grouting to? Do you intend to use regular cement, or a microsil product or a chemical grout??

 

[civilperson]

I recommend NOT grouting the annulus exterior to the pipe used as vertical vent. Rather, drive the pipe with a standard piling rig and auger the interior spoil out of the top of vacuum excavate if depths are shallow. Leave the top of the pipe pile above finish grade to assure minimal water flow from surface and epoxy seal the intrusion into the tunnel.