Normal Loads
Normal Loads
(OP)
I am starting a direct shear test for the first time. I have read several refereces but have no idea what normal loads to start with. I am dealing with an SC soil. Can anyone give me some idea what normal loads to start with and/or in what increments to increase them?
Thanks
DRQC
Thanks
DRQC





RE: Normal Loads
First if the sample is undistrubed, all selected normal loads should be at least equal to the normal pressure that the sample was under prior to collection.
Second, the normal loads should cover the range of normal loads of interest to the project.
RE: Normal Loads
RE: Normal Loads
I respectivelly disagree. If you are considering strength of in-situ soil and the application is a cut slope, there may be a design field stress imposed on the soil element that is less than the current state of stress. You should consider both the existing stress and the proposed stress (whether greater or lesser) in defining the normal loading.
To BigH, while a TXC may also appropriate, just because there is some potential for consolidation, I'm not sure that would preclude the use of a DDS to evaluate the soil strength. Then again. . .
f-d
¡papá gordo ain't no madre flaca!
RE: Normal Loads
The other consideration is failure mode. Direct shear is basically a plane strain test where you are forcing the failure through a particular plane. Triax allows the shear to happen with more freedom, and you will typically obtain lower strengths compared to direct shear.