Micaceous soils

[lcw818]

Is there any information on micaceous soils? (e.g. bearing capacity, phi angle, allowable side friction, or lateral soil modulas) Can you use "blow count engineering": my driller did not produce any samples suitable for testing? The stuff feels so greasy I wonder whether there is any side friction for drilled piers.

 

[VAD]

SPT would be suitable. Indeed, difficult to obtain good undisturbed sample. Re shaft resistance, if you are not comfortable try belled piers and design based on end bearing.

 

[lcw818]

Thanks

I would like to use end bearing and/or a bell. Problem is this is an existing pier group and I have uplift to consider. Can I use blow counts to estimate a phi angle and then a friction coef.

 

[fattdad]

The presence of mica will affect your blow count correlation to friction angle. Mica flakes are like little bits of teflon dispersed throughout the soil matrix. The SPT may not adequately characterize how these flakes will affect the overall friction angle. There are micaceous soils with friction angles in the single digits and case studies of failures to go along with them. . . .

f-d

¡papá gordo ain’t no madre flaca!