Digging a tunnel, We just entered a heist movie - Now we need rules Options

[Daishi]

Does anyone know what the barier rating of loose rocks and dirt would be?

I would say the range for earth would be from Heavy Material (6/7) to Heavy Structural Material (16/13) depending on composition. Loose soil on the low end with solid hard rock at the top. For the loose rocks we'll have to dig through I'm thinking 10/9 would be appropriate. That puts it a bit under the barrier rating for brick. The rocks might be harder than bricks, but they won't be nearly as solidly mortared together.

I think there are additional items to consider... getting rid of the rocks/earth is not a problem (well, a minor one at least), the real problem is how they are going to cope with 1) shoring the tunnel so it does not collapse 2) what happens if they hit a void underground and 3) what happens when they hit gas pockets. I work for a tunneling contractor, and these are issues we deal with on a regular basis.

Depending on where exactly the job is at, the earth can be very different. For instance, in Texas, it ranges from a very wet sand (gulf regions, Houston for instance, was built on a swamp) which requires ways fo getting the water out of the earth so it doesn't flow in on you (usually invloving a series of large pumps dropped into the ground by way of vertical shafts around the area to be tunneled), to solid granite in North Texas that requires specialized machinery (explosives are no longer allowed in Texas to break up rock).

Modern day shoring is accomplished through a pipe casing that is jacked into place, series of plates that are bolted together as you go, or with wood beam supports. I am sure something can be come up with that is easier and less bulky to work with, but even a rock tunnel is going to need some kind of shoring, otherwise lose rocks will become a hazard.

Gas pockets can be dealt with by use of gas masks, but you gotta have them with you to use.

Just my thoughts on the matter.

Thanks for the info. I had already thought a little about shoring the tunnel and was going to go with wood beams or 2070 imitations as it seemed to be most easily acquired and most easily manipulated illicitly. Though now you've got me thinking about what would they use in 2070. Spray-on nanites to bind the material together into a solid plate? Something like Universal Sealant perhaps. Might be a bit pricey for the whole tunnel, but it could be a worthwhile investment.

Gas masks are always handy, so we'll have those. What does happen when you hit a void? Also, how long does tunneling usually take? Timing is something I'm having a hard time getting a sense of. I believe we'll be tunneling through very rocky soil.

[Dumori]

Also how much shoring dose a 10m tunle need?

[Draco18s]

Also how much shoring dose a 10m tunle need?

3. Every 10 feet.

[DMFubar]

I would say the range for earth would be from Heavy Material (6/7) to Heavy Structural Material (16/13) depending on composition. Loose soil on the low end with solid hard rock at the top. For the loose rocks we'll have to dig through I'm thinking 10/9 would be appropriate. That puts it a bit under the barrier rating for brick. The rocks might be harder than bricks, but they won't be nearly as solidly mortared together.


Thanks for the info. I had already thought a little about shoring the tunnel and was going to go with wood beams or 2070 imitations as it seemed to be most easily acquired and most easily manipulated illicitly. Though now you've got me thinking about what would they use in 2070. Spray-on nanites to bind the material together into a solid plate? Something like Universal Sealant perhaps. Might be a bit pricey for the whole tunnel, but it could be a worthwhile investment.

Gas masks are always handy, so we'll have those. What does happen when you hit a void? Also, how long does tunneling usually take? Timing is something I'm having a hard time getting a sense of. I believe we'll be tunneling through very rocky soil.

Well, when digging by hand (believe it or not, that is still the primary method... those big boring machines you see on tv and in Oceans 13 cost millions... I believe the last time we rented one, it was for a cost of about $500k per month), figure for Rock you will get approximately 2-3 feet of progress per 10 hour shift. Looser soil conditions will go faster, but you will also have to spend more time putting up shoring, so about 12-14 foot per shift there. This is for an approximately 4' Diameter Tunnel. A 12 foot diameter tunnel would be about 3 foot per shift. Using drones, etc. I would double or triple those rates per shift.

I definitely think that nanite spray would be a way to go. Even today they have machines that spray concrete walls on the tunnel as the machine pushes forward. I don't think the cost would be too prohibitive as this would probably be the standard in many forms of industry (building construction, etc.).

As to how much shoring is needed, again, it would depend on soil composition. Rock does not require as much as loose soil (clay or sand). So you can probably put up beams every 10' or so as Draco18s suggests. For looser soil, we have to put up beams as well as boards between the beams, completely sealing the tunnel in. Otherwise, you start having the earth come in on you, sometimes with drastic results (many years ago, a former company I was with had an employee that took a single 2x6 board out of the wall to replace, without putting in anything to support the load. The entire face came in on him, he lived, but it was a miracle that he made it).

Hope that helps, and if you have any further questions, just fire away, if I can't answer them, I have engineers and estimators nearby I can ask.