HELP NEEDED: uniaxial and triaxial test

PFC
,
1

I am working on the example of “Genesis and Testing of a Soft-Bonded Material”. The goal is to obtain a strength value from the uniaxial test, and a few triaxial tests to calculate cohesion and friction angle to be used in slope stability models.
When I run the simulation with my laboratory-obtained parameters I get strangely high strength value (around 500 MPa), while my triaxial are around 50 to 100 MPa.

These are my input parameters - from the laboratory data and slope simulations:
[igap = 0.0*davg ]
[emod = 42.8e9 ]
[kratio = 2.5 ]
[fric = 2.31 ]
[ten_mean = 19.6e5 ]
[ten_std = 0.0 ]
[coh_mean = 19.6e6 ]
[coh_std = 0.0 ]
[soft = 0.0 ]
[cut = 1.0 ]

Is there a difference between running a UCS with and without using domain distortion?
If I run a simulation for ucs and triaxial shouldn’t I get consecutively increasing data?

Thank you for your input,
Agata

2

I have done UCS test my strenght is increasing continousaly whereas in Triaxial it is falling and with my understanding this is due to not using appropriate model or try with diffrent loading rate.

3

Thanks for your reply, the stress and strain are increasing inside the uniaxial test, when confining pressure is increased (10 kPa, 100 kPa, …) in triaxial test is also increasing. however when you have no confinement strength should be lower than the strength in triaxial tests. This is how you can use mohr-couulomb criterion to calculate cohesion and friction angle.