A silty/clayey gravel stratum, SPT sampling, 25-35 ft depth with water table at 18 feet. Loose to medium dense. SPT samples yield fragments of larger gravels which, coupled with experience in the area, indicates to us that there is a significant percentage of cobbles to gravels. Liquefaction...
The force=KX. Draw the freebody diagram, spring, fixed on one side, deflected on the other resulting in...F=KX. As long as the deflection in total between the building wall and the soil nail wall is in the range of strains where the foam performs elastically, K is the load. More than if it were...
PEinc,
The physics of this situation are not an analog to person standing on a foam floor.
The foam behaves elastically, seismic deflection can be calculated generating a resisting force, kx where k is the spring constant, x is the deflection.
PEInc,
Sorry to be unclear:
With the proper thickness,the stress/strain curve for the foam results in very low load transfer at anticipated differential movement during shaking.
I am waiting for the structural engineer to analyze anticipated seismic deflection then the load generated...
PEInc,
We thought about using a detail as you propose, but the wall height varies, top of wall is sloped so it becomes complex and expensive to construct. The compressible foam seems to be a pretty good option, however, I'm waiting to hear back from the structural engineer if they agree.
THANKS!
MotorCity,
No room for grading, leaving a void is not practical for drainage and pedestrian traffic reasons. The terraflex foam offers a low lateral pressure option, not a zero lateral pressure option.
HotRod10
Thanks much. The soil nail wall could be setback to form a a wider gap for the top 3 feet or so to accommodate a greater thickness of terraflex foam.
A building is to inset into a hillside to a depth of about 18 feet. Setbacks do not a allow a sloped excavation so a soil nail wall is being constructed for shoring. Our contractor has suggested to the owner that constructing the soil nail wall as a permanent part of the structural system will...
And another option for fill is locally available "washed" rounded alluvial rock, 0.5 inch to 3 inch diameter. Rock is hard quartzite-placed in confined conditions and compacted to form the fill, I would expect less settlement than for a compacted gravel and sand mixture. Anyone care to comment...
Rock under the majority of the tank will be overexacavated to minimum of 3 feet of fill under that portion of the tank.
I am also exploring the idea of preloading with placed fill to simulate tank loading for two to three weeks. Fill would then be removed and concrete poured.
Questions posed to forum (and to project structural designers) geotechnical questions for structural.
Given a maximum of 0.05 feet of differential settlement over 20 linear feet can a concrete tank be designed to prevent cracking and consequent leakage?
If not then what is acceptable? How are...
Big H
Elastic settlement using conservative modulus values with a FOS of 2 results in about 0.5 inches. I have never spec'd a fill this thick to support a structure, my experience with fills of 6-7' our local gravels and good construction control leads me to believe that the settlement will be...
