Building on a mountain side with fault lines
Building on a mountain side with fault lines
(OP)
There is a .25 acre residential plot on the side of a mountains in Utah. There is houses all around it, but they were all built 30 years ago when the building code was not as strict. The property is on a pretty good slope. After the survey was done, it was found that the property had 3 fault lines cutting the property into about 3 equal sections. Because of this, the property was not able to be built on. The question is if you put in reinforced cement pillars on each of the outside sections deep into the ground and then connect them with steel beams, so bypassing the middle section all together, wouldn't that meet the building code?
I have attached a quick picture of what I am talking about. The blue circles would be where the cement pillars would be install. Or can you never cross any fault line when building a house? Some reason in my mind I would think the 2 outside sections would have the same stability and the middle one would be the one that would flow the other direction in the case of a earth quake. I could be completely wrong since I study Mechanical not civil. Thinking about it more, I think i am trying to apply tectonic plate movement to simple faults on a mountain side, as if the outside sections would move the same, or shift the same since they both are up against the middle section. The code probably has more to do deal with mountain soil movement and stability then anything to do with earth quake stability. If this is right, then it wouldn't matter if you connect the outside 2 sections, the only option would be to put the cement pillars in deep enough to overcome the issue of the soil movement. Again, I am a mechanical not civil so these are all guesses.
Thanks
Brad
I have attached a quick picture of what I am talking about. The blue circles would be where the cement pillars would be install. Or can you never cross any fault line when building a house? Some reason in my mind I would think the 2 outside sections would have the same stability and the middle one would be the one that would flow the other direction in the case of a earth quake. I could be completely wrong since I study Mechanical not civil. Thinking about it more, I think i am trying to apply tectonic plate movement to simple faults on a mountain side, as if the outside sections would move the same, or shift the same since they both are up against the middle section. The code probably has more to do deal with mountain soil movement and stability then anything to do with earth quake stability. If this is right, then it wouldn't matter if you connect the outside 2 sections, the only option would be to put the cement pillars in deep enough to overcome the issue of the soil movement. Again, I am a mechanical not civil so these are all guesses.
Thanks
Brad





RE: Building on a mountain side with fault lines
Mike McCann, PE, SE (WA)
RE: Building on a mountain side with fault lines
Mike McCann, PE, SE (WA)
RE: Building on a mountain side with fault lines
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RE: Building on a mountain side with fault lines
When you look at utah mountians and see the lines in them, they call them fault lines, so I am not sure why these wouldn't be called fault lines?
Thank
Brad
RE: Building on a mountain side with fault lines
Fracture zones can be smaller faults, per se, not shown on geologic maps, but they can also be areas where the rock has fractured or weathered due to freeze thaw action. It depends on your local area.
I would really be surprised for three fault lines, where documented seismic movement has occurred, to be located on one building lot. How big is the lot?
Mike McCann, PE, SE (WA)
RE: Building on a mountain side with fault lines
If those faults are active, I wonder about the wisdom of erecting a new building amongst them, no matter the countermeasures and no matter the existance of other buildings. Unless it's a depot without people living inside. Also, maybe I missed something, usually a minimum safety distance is required from active official fault lines like in California codes.
If they are not active, then the issue is just that of a mechanical dishomogeneity or fractured area.
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