Parking Lot Grading with Frost depth

[wizman]

Hi to all,

I'm new to this forum and new in practicing engineering.

My question is regarding parking lot grading.

In frost susceptible country, are you taking out the original soil for the grading of the parking lot?
Or to rephrase how deep should the grading for parking lot be in a frost zone area?

Thanks.

Regards,
Ron

 

[civilman72]

Depends on a lot of factors, but you generally not design a pavement section to get below a given frost depth. Most important component to avoid differential settlement (often accelerated by freeze/thaw) in the subgrade is to develop a consistent material type and moisture content during construction. You should consult a geotechnical engineer to provide a pavement section design.

 

[wizman]

Thank you for your response.

Regards,
Ron

 

[ACtrafficengr]

As civilman said, it's uncommon to dig down to frost depth replace soils for a parking lot, or even a roadway.

Remember that there are three factors needed to get frost heave: frost susceptible soil, cold, and water. Do you know the local subsoil type? Unless the water table is very close to the surface, gravels and sands aren't susceptible. They don't have enough capillarity to bring water up into the frost depth. Clays are too impervious to draw water up from the water table and create frost lenses. Silts, silty sand and silty clay soils create the most problems.

In upstate NY, we get frost depths of four feet or more, we have a wet climate, and some areas have silty soils. Generally, providing a good subbase and drainage is sufficient. It wouldn't hurt to check with a geotechnical engineer familiar with the area, just to be sure.

 

[wizman]

Much appreciated for your help civilman and ACtrafficengr.

Regards,
Ron