Geotechnical Aspects of Peats

Geotechnical Aspects of Peats

Presenter: Dr. Cor Zwanenburg
Title: Geotechnical Aspects of Peats
Launching Date & Time: 01 December 2014 12:00pm GMT


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Session Question & Answer [CLOSED]

Lin Zhang

Thank you very much for the presentation Dr. Zwanenburg, why is peat usually not considered to be overconsolidated please?

Cor Zwanenburg

Dear Lin Zhang, thanks for joining the webinar. Peat layers are usually found in the top layers of the subsoil. Since peat is very compressible high loads in the past would result to thin peat layers. Besides, I am speaking mainly from my experience were I never found peat layers that did carry high loads in the past. That does not mean that truly overconsolidated peats do not exist.

Diana Martins Marques

First of all, thank you very much for this seminar. I would like to ask about in situ tests in organic soils. I realized that, a lot of times, in situ tests underestimate values for Cu and Deformability paramaters (actually the "problem" is in formulas used, once we use the ones applied for clays). Is there any formulas for organic soils? Which test do you think will be the most accruate to detemrine Cu and E? The best option will be to calibrate this data with laboratorial tests but most of the time we don't have time to perfom these lab tests. Thanks in advance.

Cor Zwanenburg

Dear Diana Martins Marques, Parameter assessment for peats is indeed difficult and needs experience. Since experience is always local (to some extent) It is difficult to give a general answer. Indeed the best option is to calibrate with lab. tests. If lab tests are not an option. I would suggest combination of field tests like field vane and CPTu, or ball penetrometer. As explained in the webinar each type of test has its specific problems when applied to peats. If field vane is successful, you could use them to compare or calibrate the penetrometer data. In that case do not forget the correction factor for the field vane which can be relatively high. If available, results of previous projects in the neighborhood can provide a useful source of information in this field.

Afshin Asadi

Thank you very much for the presentation. My name is Afshin Asadi from Malaysia. May I know your idea about having a "floating foundation system" in peat by using the buoyancy. We may use some light weight materials, air-trapped objects, or light density liquids. Regards, A. Asadi

Cor Zwanenburg

Dear Afshin Asadi, In my experience expanded polystyrene can provide a good foundation for floating or nearly floating foundations. I know several projects in which roads are founded on EPS successfully.