Lateral earth pressure

jhmche · Jul 18, 2017

Hi guys, mechanical engineer here. I need to get a lateral earth pressure to perform some calculations on a part I'm designing. I have no experience in the geotechnical field and need some tips.

To give you guys an idea of what I'm working with, it will be a cap which will fit over the end of a casing pipe buried in the ground. Since this product will be used in all regions of the US, which soil type would exert the most pressure against it, and where can I look to get a pressure coefficient for it?

oldestguy · Jul 18, 2017

If you are considering all parts of the US, you probably will have frost to contend with. These high pressures and lifting situations can occur. I doubt that a "fits everything" design would be economical for that reason. I'd add to the specs for the northern 1/3 of US that all backfill out to a distance from the installation a distance equal to depth of facility will be backfilled with non-frost susceptible fill. Other than that, I'd assume a density of backfill at 150 pounds per cubic foot of liquid to account for a variety of soil and water conditions.

jhmche · Jul 18, 2017

That makes sense. Before checking back here, I ended up using a value I found from a table that had a unit weight of 156 pcf. I appreciate the input.

SlideRuleEra · Jul 18, 2017

jhmche - Good advice from oldestguy. Parts of the US have a year-round water table that is essentially at the surface of the ground. In addition to designing the cap for lateral pressure, suggest designing to be watertight.

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