tenguy23
Structural
- Apr 5, 2007
- 8
I'm analyzing an old environmental lift station (effectively a huge basement). It was designed in the early 1960s as a lift station with building on top, but now it will be demo'd with the basement portion only being reused for a future lift system.
Dimensions are 31.67' deep from ground level with a square plan dimension of 24.5' x 21.83' (15" to 18" walls). Borings taken adjacent to this "basement" are primarily clayey/silty soils with Q,u ~ 1 to 1.25 TSF (N values ranging from 6 to 10).
I'm concerned about buoyancy since this structure is next to a small creek adding about 22' of buoyant force on the structure. I want to consider effects of skin friction of the side soil (on all (4) sides) to help out with adding to my total DL weight counteracting buoyancy, but don't know how to go about calculating it. If I were to consider this as a huge pile with perimeter of 92.67', the alpha-method with alpha~0.5 gives me a total skin force of 2,471 kips, which seems to big.
Any ideas of how to calculate?
Dimensions are 31.67' deep from ground level with a square plan dimension of 24.5' x 21.83' (15" to 18" walls). Borings taken adjacent to this "basement" are primarily clayey/silty soils with Q,u ~ 1 to 1.25 TSF (N values ranging from 6 to 10).
I'm concerned about buoyancy since this structure is next to a small creek adding about 22' of buoyant force on the structure. I want to consider effects of skin friction of the side soil (on all (4) sides) to help out with adding to my total DL weight counteracting buoyancy, but don't know how to go about calculating it. If I were to consider this as a huge pile with perimeter of 92.67', the alpha-method with alpha~0.5 gives me a total skin force of 2,471 kips, which seems to big.
Any ideas of how to calculate?
