Fault Lines

[bank]

I am going to have to design a concrete parking lot on top of a fault line. Does anyone know of specific measures I need to take or resources where I can find out how to accommodate the fault line and protect the pavement and drainage systems?

 

[GoldDredger]

Interesting, I've heard of not constructing buildings on/across fault lines, but a parking lot?

Be curous to know what the geotechnical report recommends for the pavement section.

I don't imagine there is much of anything you can do if there is a sizeable seismic shift. You wouldn't be able to predict heave, subsidence or lateral shift (or combo of all three).

As far as the subsurface drainage, maybe use of a flexible pipe rather than ridgid pipe.

 

[epongra2]

Here in So Cal "fault lines" or fault zones are often dealt with using a structural setback and therefore are an ideal location for parking lots.

 

[civilperson]

No possibility of "quake proofing" anything on a fault line. A parking lot seems like a best use for this location!

 

[msucog]

is it a parking lot or parking deck? and is the fault active (i guess i'm asking: in what part of the country you are located)?

 

[bank]

The project is in Brazoria County, Texas, just south of Houston. The geotechnical report recommends HMAC pavement, but the design criteria provided by the client requires concrete. Another twist to this is that we will have to raise the parking lot three feet to bring top of pavement above the Base Flood Elevation.

 

[cvg]

you need to answer two questions

1) is this a historically active fault?
2) what is the probability and risk of movement on the fault?

My guess is that since you are in Texas, the fault may not be active. Even if it is, large scale movement may only occur within a geologic timeframe. What is the creep rate and is it constant? Can it even be measured?

The probability of movement (other than creep) within the design life of the pavement is exceedingly low. The damage caused might be only minor. So the resulting risk is likely to be so low that any design accommodations may be a waste of time and money.

 

[muuddfun]

Definitely don't worry about it. My guess is that in Houston what you have is not a fault from tectonic forces that would create earthquakes, probobly what you are looking at is a fissure from subsidence from goundwater or oil extraction. You may experiance some pull apart as well as some vertical movements on it during the life of your project. There is not much you can actually do about it except maybe provide some flex couplings for you underground utilites. Any concrete paving will likely be cracked realy quick if there is any movement on it. Tell the owner that either way if you use concrete or HMA you need to be prepared to maintain it.

 

[msucog]

i wasn't sure if you were describing a parking deck or pavement...being a pavement on the ground, the seismic concern would be subsidence and/or spreading due to an active fault or slope instability issue. whether it's ac or concrete, it doesn't change the situation and i don't think there's a lot you can do about it. even if it's a grassy lawn area, subsidence and spreading will effect it more or less the same. if the owner wants to minimize cracking to due very small movement, then look at adding rebar, adjusting the mix, etc. otherwise, don't get too wrapped up trying to earthquake proof the pavement. if it were a parking deck, then you'd have other life safety and structural issues to deal with.