Looking for shear strength properties of mudstone?

[adelahunty]

Hi,

I'm looking for a reliable source of data for the shear strength properties of mudstone. Everywhere I have looked so far does not give any values. The mudstone I am looking for in particular is located in the North East of the UK, but any properties will give me some sort of an estimate for now.

Thanks

 

[dik]

You need geotech info. I assume by mudstone, you mean shale. Shear strength and bearing capacity can vary considerably.

Dik

 

[fattdad]

In our practice (I work for a department of transportation), we'd avoid shale or mudstone in earthwork. It does happen though. Our design life is 75 years so we are looking for long-term performance. In that instance, we'd take the mudstone or shale, completely disaggregate the rock, normally consolidate the sample from its liquid limit into the direct shear box (to three different normal loads) and then shear the sample. We would not base our design on rock mass rating or kinematic evaluations as we may for a more durable rock.

If I think of it, I'll attempt to find a citation that shows the procedure.

f-d

ípapß gordo ainÆt no madre flaca!

 

[Okiryu]

Our local mudstone has some expansive issues and I do not recommend it neither for earthwork. Our mudstone has also slaking softening due to drying-wetting cycles. For foundation design, we normally run unconfined compressive strength tests for checking qu. For shear strength, perhaps you can look at typical values for hard clays. I would like to see other opinions, though.

 

[adelahunty]

Thanks for the responses. This is a university project so I obviously don't have the resources to do any testing, hence why I am trying to find parameters through research and empirical relationships.

There is sandstone which I have parameters for about 1-2m below the mudstone. Would it be recommended to pile to the sandstone instead?

 

[dik]

Sandstone can be a far better material...

Dik

 

[fattdad]

is this a homework problem! Please don't waste our time doing your homework.

Otherwise, I'm a bit confused. . . Universities often have laboratories that do direct shear testing. Not sure why your research can't mobilize some testing in a university.

f-d

ípapß gordo ainÆt no madre flaca!

 

[HENRYZAU]

What's the geotechnical problem? Cut slope?deep foundations? Driven or bored piles? Tunnelling? Retaining wall? Shallow footings? Mudstone is not a good material but in some cases you have to deal with them or even rely on them.