Swimming pool load 1

[wallguy]

What loading should swimming pools be given behind MSE walls? There seems to be differing opinions out there. Assuming the pool load is within twice the height of the wall.

 

[BigH]

Above ground or below ground pool?

 

[civilperson]

Horizontal load of 62.4 pounds/sq. ft. per vertical foot.

 

[wallguy]

Sorry BIG H, it will be below ground gunnite with a paver deck around the pool. New information says it may be 6 feet away from a 8 foot height section so it will be in the zone of influence.

I thought a dead load of 150 to 250 psf might be in the range but just do not have the experience as a non engineer to know that to be true.

Thanks for the help on this one.

 

[BigH]

- had this written once before but unreliable connections out here.

Your MSE wall would be reinforced for about 0.7 to 0.8 times the height of the wall - i.e., 5.6 to 6.4 ft (see BS8006). Therefore, the pool would not be within the zone of the reinforced mass and therefore not within the zone of influence of the active earth pressure 'failure plane'. (45 + >30/2 or >=60 from horizontal. The horizontal pressure that civilperson indicated would be an "overturning" pressure against the reinforced mass - but as you don't have soil - only water, for this height of wall, it is basically (not quite true) a wash. Check the global stability of a slip surface going from behind to underneath the wall - if okay, I'd say you would be okay. Of course, your "wall" must satisfy sliding and overturning which, for the mass described above, I see no reason it wouldn't.

 

[wallguy]

BigH, thanks again, I know we have done a number of walls in front of pools but have never had a firm confirmation on the nature of the load. We have always left it to the wall designer to work it out. Now I have a designer wondering which is the right way. I will look into getting a standard for us on this. Our water issue we have also suggested all gravel backfill and drainage through the wall in case of leaks. In cases of pools on slopes we have suggested global stablity be run especially with life issues and larger pool deck areas.

 

[civilperson]

When the pool splashes over the edge of the pool and saturates the backfill of the MSE wall to the depth of the pool, a horizontal force will exist.

 

[BigH]

only if 'enough' water splashes over the edge to saturate the fill. In any event, the reinforced zone fill, being granular, would drain the water faster (downward) than the water actually mounding up within the fill I would think. And also, water would seep out between the facing panels if it does want to "rise". As a worst case - use a "near surface" hydrostatic force and I think that you would find for a 8 ft wall, it will make little difference in practice.