Pipe Bedding on Very Soft Clay in Coastal Region

[sykimm]

Dear all,

I'd like to design of pipe bedding on very soft clay stratum in coastal region.

There is very soft clay ( c = 0.5 kg/cm2, SPT N=0~2) of 10 m thick depth.

Water depth will be less than 5m.

Any experience like this matter would be helpful to me.

 

[fndn]

A cohesion of 0.5 Kg/cm^2 is not so bad, just am wondering if that value could be qu, the unconfined compressive strength. Where qu=2c. Either case, a low blow count, N, is a given in soft to medium soft clays. In such a case, we would place a geofabric first to separate the stone from the clay, increase the bedding thickness to a minimum of 30 cm, and limit the excavated trench width to slightly larger than the pipe diameter.

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[sykimm]

Thank you, "fndn".

As you noted, c value in previous post was incorrect.
factually c=0.05 kg/cm2. SPT N-value is 1 to 2 of very soft clay.

If you have any experience, please let me know.

 

[fndn]

My experience was in watermain pipe project. We had soft clayey silt, and I asked for a geaofabric and doubled the 6" bedding to 12". That was about 6 yrs ago, and our C value was close to 0.7 Kg/cm^2. Hope this link helsp:

http://www.concrete-pipe.org/designdata.htm

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