Stress distribution of a rock socket 1

[peelwvu]

We have a bridge project where the bridge pier spans a subway. In order to avoid loading the subway it was proposed that we put caissons on either side of the subway to carry the load from the bridge. The top of the subway is approximately at the top of the rock so the caissons will be socketed into rock alongside the subway walls. From the outside edge of the rock socket to the subway wall is 5 ft. There is no room to move the caissons further away because then we have conflicts with buildings.

Can anyone give me a reference to determine the stress that will be imparted to the subway wall from the rock socket. The rock sockets are 16 ft. long extending to about the bottom of the subway and are carrying some pretty substantial loads.

Is there any way to minimize the stress on the wall? Also we have concerns about whether the vibrations during construction will be too much for the subway wall or the surrounding buildings?

Thanks

 

[Ron]

Ok....let's get back to basics.....Not much different than guardrail post embedded in concrete. Similar distribution and SRE's solution is accurate. Provide a lateral buffer!

 

[PEinc]

dik, here is Skyline Steel's presentation from last week. I watched the webinar.

http://www.skylinesteel.com/File Li...kyline-Steel-Webinar_Geo-Solutions_112117.pdf

http://www.PeirceEngineering.com

 

[peelwvu]

thanks everyone.

PEinc, we don't think there's going to be enough room to fit a pile cap for micropiles.

We decided to present the option of drilling a larger diameter hole along the subway and backfilling the annular space with either sand or bentonite. We saw the use of bentonite on another project. Does anybody have any other experience using this?

 

[SlideRuleEra]

Bentonite powder is a big "mess". It, of course, swells when exposed to water and is a slippery as grease. When well contained, it is virtually waterproof.

We used it, in powder form, for the (relatively) impervious liner for a coal bottom ash pond. Layers of compacted soil, both above and below were used to contain the bentonite. For the next pond, switched to a manufactured bentonite pond liner (the carpet-like structure of the liner, plus a soil layer covering, provides bentonite containment).

Also have used a perimeter bentonite slurry trench to cut off flow of groundwater into a temporary excavation.

Surely there is something better than bentonite... at least the type bentonite I'm familiar with.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net