Rock Blocks and Rock Pins
Rock Blocks and Rock Pins
(OP)
Hi,
I am analyzing a 35' Keystone Wall w/ 22' GeoGrids.
Due to rock in the reinforced zone, I have to provide rock anchors or pins for the lower 15' of the wall to tie the GeoGrids.
I estimated that if I place the rock acnhors/pins at 6' c/c spacing along the length of the wall to tie the GeoGrids, then I would need 3" dia concrete grouted coreholes w/ 1" dia 50 ksi steel rods inserted in the center,to provide me with 18kips pullout capacity. The embedment length into the rock would be approximately 48 inches.
I am now trying to figure out the size of a block of rock that will be influenced by this 18kip pullout anchor. I am assuming a cylindrical shape of the rock block that will be pulled out.
The rock at the site is Diabase, with varying degree of weathering, fractures and joint spacings. I need the block size which can be used as a limiting factor to verify the the feasibility of installing these anchors in the field.
Please provide your valuable input and/or any suggestions - Thanks Chikkad
I am analyzing a 35' Keystone Wall w/ 22' GeoGrids.
Due to rock in the reinforced zone, I have to provide rock anchors or pins for the lower 15' of the wall to tie the GeoGrids.
I estimated that if I place the rock acnhors/pins at 6' c/c spacing along the length of the wall to tie the GeoGrids, then I would need 3" dia concrete grouted coreholes w/ 1" dia 50 ksi steel rods inserted in the center,to provide me with 18kips pullout capacity. The embedment length into the rock would be approximately 48 inches.
I am now trying to figure out the size of a block of rock that will be influenced by this 18kip pullout anchor. I am assuming a cylindrical shape of the rock block that will be pulled out.
The rock at the site is Diabase, with varying degree of weathering, fractures and joint spacings. I need the block size which can be used as a limiting factor to verify the the feasibility of installing these anchors in the field.
Please provide your valuable input and/or any suggestions - Thanks Chikkad





RE: Rock Blocks and Rock Pins
That said, are you sure you need to tie the geogrid to the rock bolts? If the rock is within the active zone of the wall, then the pressure on the wall will be less than if the rock were not there; assuming of course that the rock is stable at the angle which it is cut. If the rock is not stable, then the rock bolts would be needed to stabilize the rock likely resulting in longer bolts.
Intuitively it seems that if the rock cut is stable and the geo grid runs from the wall facing to the rock face, then the wall will be stable. Since these walls are really just gravity retaining walls, if the wall (i.e. the reinforced part) is stable and the rock face is stable then the system is stable.
RE: Rock Blocks and Rock Pins
RE: Rock Blocks and Rock Pins
RE: Rock Blocks and Rock Pins
Frank Lucca M.I.Exp.E.
www.terradinamica.com