Coefficient of friction between soil and steel 1

[Mohanlal0488]

Hi Guys

I have done a number of structural designs whereby the support structure has to be designed for a case whereby they would be dragged on soil.

When it comes to the dragging force I have in the past assumed a coefficient of friction of 0.7 which I assume is conservative based on the source where I attained the number. In the IOM manual there is a section detailing the dragging process and a note that requires the client to ensure that their coefficient of friction is less than or equal to 0.7. I also include a source that can be used for the experimental process to attain the results (see attached image).

Are there any resources and or other information which I could use?
Are there any standard tests which can be used to attain the coefficient of friction between steel and soil?

I have struggled to research and find information on this topic.

 

[PEinc]

https://search.yahoo.com/search?fr=...20141007&p=friction+coefficient+steel+on+soil

http://www.PeirceEngineering.com

 

[LRJ]

What you need is the soil:steel interface friction angle (δ). For cohesive soils this is usually obtained using ring shear tests, though 'CamTor' or tilt table tests may be better for certain applications (e.g. pipelines or other low normal stress design cases). Without knowing the specifics, the coefficient of friction may be described as the ratio tanδ/tanΦ' (where Φ' is internal friction angle). Alternatively, it may be akin to an α factor, which can be described as τ/s_u, where τ is the interface shear stress and s_u is the undrained shear strength.

In terms of relevant references, it really depends on your application. α factors vary depending on foundation type/installation method.