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Underground City Design

caters

Sage
I have already taken into concern renewable sources and several other factors.

Here is what I have so far:

Homes

The homes are all at the borderlines of the city. They are chambered and most of what is in the homes is underground. This gives room for wild animals while still allowing a civilization to thrive.

Buildings

The buildings are more towards but still not quite at the center of the city. There are 2 hospitals, 1 general and 1 children's as well as a bank, a store, a restaurant, a lab, and 5 schools.

Education

This education hasn't been established except for 5 basic levels. Those are preschool, elementary, middle, high, and college.

Food

Robin and Lisa have more than enough fruits and vegetables. They don't have any domesticated animals used for meat or eggs yet. Meat and eggs is handled by hunting. Hunting is 1 of a female's jobs. Males do it too but only when the females can't do it.

Light and Time


This is 1 big issue. However, I have solved it by having part of the homes and buildings above ground and the people doing just as well above ground. At least, I think I have. Time during the night is not nearly as important as during the day.

Ventilation

Oxygen easily gets into this underground system via diffusion and likewise CO2 easily goes out. Plants also draw CO2 from the atmosphere, facilitating diffusion of CO2 from high concentration(underground) to low concentration(atmosphere) Oxygen goes the opposite way again via diffusion. And this keeps happening. The only way these people get hypoxic underground besides lung and heart issues is if tunnels collapse on them. This tunnel collapse leads to injury and in some cases hypoxia. Ventilation is no problem.

Questions


1) Will simple diffusion really work for gas exchange between the underground system and the atmosphere like it does in human gas exchange? In other words would this whole biosphere(underground system with people producing CO2, Plants on the surface producing O2, Bacteria producing both those 2 and more) be like giant lungs?

2) Even with part of every building and home above ground, will this sunlight(or moonlight at night) work all the time for telling daytime from nighttime? I mean, it will probably work most of the time but is there a point where the difference between sunlight and moonlight is so miniscule that I will truly need lights there? I know that sometimes(but rarely), moonlight can be just as bright as sunlight(I sometimes get moonbeams in my room from all the moonlight outside).

3) If an earthquake happens, will people underground be in more danger than people above ground or not? I can think of several pros and cons for each.

Stay underground Pros:

Minimum risk of communicable illness

Babies already born kept safe from injury

Most familiar territory so less stress

Stay underground Cons:

Aspiration pneumonia(not an illness but nevertheless a concern)

Risk of hypoxia in tunnels

Risk of injury anywhere but especially in tunnels(fractures, myalgia(muscle strain), organ failure due to loss of oxygen)

Above ground Pros:

Quick evacuation

Knowing the duration of the earthquake

No aspiration pneumonia

Above ground Cons:

Higher risk of injury than underground(fractures, impaled, burns)

Babies aren't safe(could jump out of sling and get injured due to the shaking)

Higher risk of illness(bacterial, viral, fungal, parasitic, doesn't matter)

Universal Cons:

Nausea(In already nauseous people, this could be dangerous)

Preterm labor and miscarriage(stress increased during pregnancy)

Not able to breastfeed(Same thing, stress can dry up milk supply)
 

CupofJoe

Myth Weaver
1) No. CO2 is heavier than air or oxygen, you would need to pump the co2 out and fresh air/oxygen in, to any underground system.
2) As for light, I've seen bundles of fibre optic cables used to bring daylight into internal and underground spaces. Very effective and low maintenance.
3) I have never heard of anyone underground wanting to stay there when there was an earthquake. I'd expect everyone to run in to the nearest open area [field, park, running track etc.] if they weren't already in a specially constructed earthquake shelter [Wiki Earthquake Resistant Structures].
Just about anything that could happen above ground can happen below ground and then a billion tons of rock can bury you in there too.
Hope this helps...
 

Vaporo

Inkling
1) No. CO2 is heavier than air or oxygen, you would need to pump the co2 out and fresh air/oxygen in, to any underground system.
2) As for light, I've seen bundles of fibre optic cables used to bring daylight into internal and underground spaces. Very effective and low maintenance.
3) I have never heard of anyone underground wanting to stay there when there was an earthquake. I'd expect everyone to run in to the nearest open area [field, park, running track etc.] if they weren't already in a specially constructed earthquake shelter [Wiki Earthquake Resistant Structures].
Just about anything that could happen above ground can happen below ground and then a billion tons of rock can bury you in there too.
Hope this helps...

CO2 is heavier than air, but I don' think it's quite as simple as you make it out to be. If it were, the air at sea level in many deep caves would be completely unbreathable. Gasses in the air tend to get mixed up enough that they can be thought of as homogeneous.

Caves can actually be very safe places during earthquakes, and I've heard a couple of stories of people being underground during a quake and never realizing that anything was wrong until they returned to the surface. Try Googling "caves in earthquakes."

Caters' questions:

1. No, a cave's ventilation will absolutely not operate like lungs. Lungs are actively working to pump air in and out, whereas a cave would rely on passive diffusion to move air in and out. If there are only a few people, this could be enough, especially if they're close to the entrance, but the deeper the cavern goes and the more people you have, the larger the ventilation problem becomes. One way to help with this is to construct a large entrance facing towards the prevailing wind and a large exit facing the opposite direction at the other end of the cavern, ensuring that there will usually be some airflow.

2. You say that every building has a part poking above ground. If they're that close to the surface, why are you worried about ventilation at all? Just put an air duct above ground and the problem is solved.

As for telling time: if they're underground all the time, why do they care what time of day it is? They'll sleep when they're tired and work whatever schedule is convenient. If they're advanced enough to build complex underground cities, then I'm sure that they can at least have a clock somewhere. I'd be more concerned about how they'd light this whole thing. If you have the city so close to the surface, you could put skylights above the streets and in the buildings (which binds the residents back to the day/night cycle, though), or rely on something like electric lights, oil lamps, or fireplaces. Actually, fireplaces could help solve the ventilation problem. Air would be constantly rising up the chimneys, sucking air out of the cave and pulling fresh air in.

3. With your city so close to the surface, you can forget that I said anything about caves being relatively safe during an earthquake. Your city is about the last place I would want to be during a quake. It would take almost same brunt of the vibrations as the surface, knocking down tunnels and just causing utter chaos. Unless they have seismographs, an earthquake will come with almost no warning, and it becomes less of a problem of deciding whether to get above ground and more of an issue of evacuating the survivors in the aftermath. I would imagine that the residents who can would take the quickest route above ground as soon as the shaking stops and forget about nausea or other consequences of being thrust into a sunlit environment after being underground for so long. Their houses are literally falling in on them. I sure wouldn't stay there.

If they have advance warning, though, I'd get everyone above ground as soon as possible. Probably the best place to be during an earthquake is lying on the ground in the middle of an open field. Compared to the possibility of hundreds or thousands of people being killed by collapsing caverns, the danger of infectious disease spreading is miniscule. And why would infectious diseases be more of a problem above ground in than in a tightly packed city where everyone is sharing each others' air?

So yes, unless your city is very deep underground it would be much safer to be above ground than in your city during an earthquake.

EDIT: I may have misread your post, though. When you say that you have part of the buildings above ground, do you mean that some of the buildings are constructed above ground and that everything else is underground, or that every building has a part poking above the surface? Either way, the city has to be pretty close to the surface, so my points still stand.
 
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