looking for shear strengh parameters of highly weathered rocks
looking for shear strengh parameters of highly weathered rocks
(OP)
Hi all,
I've browsed few rock mechanics books such a Hoek et al on shear strength of rock; it would be a great help to me if I can get some ball park figures to start off with before I do a full scale testing. The rock is highly weathered or fragmented. The RQD values of the rock core samples are ranging from 0 to 20%. The rocks are predominantly sandstone. This is the same area in my previous post. The rock layer is 3 to 10m below the natural slope level depending on the profile. The slope is highly saturated. A 5 gallon bucket can be filled in 3 minutes from a 20 feet horizontal drain.
Thanks
I've browsed few rock mechanics books such a Hoek et al on shear strength of rock; it would be a great help to me if I can get some ball park figures to start off with before I do a full scale testing. The rock is highly weathered or fragmented. The RQD values of the rock core samples are ranging from 0 to 20%. The rocks are predominantly sandstone. This is the same area in my previous post. The rock layer is 3 to 10m below the natural slope level depending on the profile. The slope is highly saturated. A 5 gallon bucket can be filled in 3 minutes from a 20 feet horizontal drain.
Thanks
RE: looking for shear strengh parameters of highly weathered rocks
RE: looking for shear strengh parameters of highly weathered rocks
I would reccomend to you the software "Roclab", freely downloadable from Hoek's website.
It overcomes some drawbacks of the Bieniawski method related to soft and very fractured rocks. Has a specific section on flysch formations. Yields conventional phi and c and Hoek & Bray parameters for slopes as well.
Pretty good when there is lack of one or few well-defined joints or joints systems.
Developed in the highway project in Greece, together with professor Marinos of Athens. I tried it out with good results, particularly in sandstone-shale sequences.
Good preliminary evaluation prior to eventual more detailed study such as the one suggested by geopavetraffic (although I fear the latter is hardly applicable in the weathered & fractured conditions remarked by longisland).
RE: looking for shear strengh parameters of highly weathered rocks
I'm adopting phi = 41 as stated in FHWA soilnail document. The value is derived from SPT N value > 50. Since we will be excavating the slope eventually, I'll assume the cohesion to be 0 on the safe side. A sheared zone was found on the 1st berm from the bottom. The rock layers are deformed & the tocks are heavily jointed.
Thanks for the reply
RE: looking for shear strengh parameters of highly weathered rocks
That's a possible conservative approach.
RE: looking for shear strengh parameters of highly weathered rocks