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why use expansive soil for backfill?? good question and the answer appears to be inertia and $$$$. Hauling away the clay soil and bringing in off-site soil or free draining material is expected to cost between $4,000 and $7,000 or more, and most contractors will not add that cost to the...

I will keep that in mind. Now that you mention the SL question, I am not really happy with the consolidation testing that was done, and I was a bit surprised at a few other results. Thanx again for your input

BigH, I have Atterberg limit results for two samples of the stiff upper OC clay as follow: LL PL PI SL 49 17 32 18 49 17 32 17 Thanx for the direction, I have W&F and see now where that is discussed. I will figure out a volume for the expansion and take a look at the geofoam options...

thanx for the info: LL = 49, PL = 17, shrinkage limit = 18, existing moisture content of this soil in the ground is between 19 to 25%, expansion index runs between 80 to 110. The swell test result was 0.44 tsf per ASTM D4546, not 1 tsf as I heard earlier. I understand this test result is...

I obtained an undisturbed sample of desiccated, overconsolidated lacustrine clay from a depth of six to seven feet at a subdivision project site, and assigned a swell pressure test per ASTM 4546. I do not have the lab report yet, but I was informed by the lab tech that the swell pressure is...

no slab in this building, just a gravel floor

Yes, wire roper stretches. I figured the 3/4" cable would elongate about 1 3/4" under the design load (7/8" deflection at each end), and added a cage of 8 -#4 bars and a #4 tie every 12" in the circular piers to address shear and help handle this deformation. Tie rods do...

The subgrade pad for this building was carved out of a hillside two months ago, forming a cut/fill situation under the building. The fill soils were not compacted. As a result one side of the building will be constructed above native, hard glacial till soils, and the other side on moist to...

JAE On haynewp's suggestion, I quickly found an "inert" closed cell expanded polystyrene (E.P.S.) product manufactured by Beaver Plastics, Ltd of Alberta, Canada at http://www.beaverplastics.com The product name is Frost Cushion, and I plan on specifying it for this job. I had a...

haynewp - Great - I love it! your right, I think that will solve the heave situation without getting into a more complicated design, and I appreciate the input. I want to thank Lutfi and ishvaaag for your valuable assitance with my problem you guys are great!

haynewp: According to the load vectors in the building drawings, the horizontal thrust from the rigid frame occurs outward on both sides of the building. The wind loads do result in thrust in one direction on opposing piers, but the DL + LL is a gravity load, and the wire rope tie holds the...

Lutfi/ishvaaag Thanks ever so much for your input. I feel better about how I am thinking of this now. Its hard not to think about frost up here in Central New York State with our -20 to -30 F wind chills lately, and this building will not be heated. yes I am concerned about shear transfer...

Lufti Thanks for the good info. This building will have no slab, just a gravel floor. I am not clear on how the lateral load will be transferred from the column base plate, thru the concrete to the cable tie. I am running the cable through/between the stem of the 4 anchor bolts, and...

The first thing I would ask is do you have any geotechnical data describing the shallow subsurface soil and groundwater conditions? What are the compressive/shear properties of the soils? Any foundation design must start with this type of info. Also, not being familiar with the this...

I have been asked to specify a foundation for a rigid frame building with a 70 foot clear span. The horizontal thrust at the base plate, as provided by the building manufacturer, is 19 kips. I have determined to use a 3/4" wire rope tie between opposite piers to resolve this lateral load...

DRC1 Interesting. Since 1980 most of my work has been in designing, building, operating and closing solid waste landfills in the northeast USA. I cannot remeber seeing any design by firms in this area where the slots or perforations were placed on top. I do remember one event when I...

darrengavin: I agree with PSlem, and the answer to your specific question is no. For example, horizontal and vertical permeability will be near equal in a lacustrine (lake laid) soil deposit if the soil texture is consistent across the zone of interest (i.e all clay or silt size particals) As...

DRC1 I'm not a fan of wrapping a drainage pipe with a geotextile filter, as the filter will most likely eventually clog. What about using graded soil filters and sizing the slots or perforations to protect the aggregte from entering the pipe? Also, I have always specified that the...

I appreciate all your comments. Many wonder why the Building Association would fight placing, what amounts to about $1500 extra for the reinforcing steel, into a foundation for multi-100K homes. The builders say officially that this might eliminate some from qualifying for a mortgage. This is...

PSlem - thanx for the quick response. I'm not sure I understand the purpose and goal of the foam blocking. Is this to reduce soil backfill loading over the footer? If so, how would this help address the potential for differential settlement? I know some foundations are designed as pile and...