Temp Retaining Wall - CSX Cooper E80 Railroad Load
Temp Retaining Wall - CSX Cooper E80 Railroad Load
(OP)
We're quoting a project that will require a temporary retaining wall to allow for construction access. This temporary wall will be nearby a railroad, and the geotech has recommended that the CSX Cooper E80 Railroad load be applied to this wall (in addition to the typical active soil pressure) to account for the lateral surcharge from the tracks. The geotech also has recommended that the wall generally consist of drilled shafts that extend into a rock socket, H-piling embedded in the drilled shaft that are cantilevered to the surface (about 15'-20'), and wood lagging in between the H-piling. (See page 1 of attached PDF.)
The CSX Cooper E80 railroad load is a typical strip load consisting of a uniform pressure of 1,882 psf over a 8.5' width. Boussinesq's Method is to be used to estimate the lateral pressure on the wall. (I used AASHTO's method - see page 2 of attached PDF.)
I made an Excel spreadsheet that computed the lateral pressure from this strip load (AASHTO method) for depths up to 15' and for multiple offset distances. I then plotted the lateral pressures on a chart. (See pages 3 & 4 of attached PDF.) I noticed in the AASHTO commentary that this procedure is suited for a restrained top (at-rest pressure), which for this type of wall (flexible) yields very conservative results. I am assuming that I can reduce these lateral pressures by a factor equal to the ratio between the at-rest coefficient (3.25) and the active coefficient (0.31), which is about 3.25 / 0.31 = 10.5. Is this sound reasoning?
NOTE - the attached PDF does NOT show the adjusted pressures.....it still shows the at-rest pressures calculated with the AASHTO procedure.
The CSX Cooper E80 railroad load is a typical strip load consisting of a uniform pressure of 1,882 psf over a 8.5' width. Boussinesq's Method is to be used to estimate the lateral pressure on the wall. (I used AASHTO's method - see page 2 of attached PDF.)
I made an Excel spreadsheet that computed the lateral pressure from this strip load (AASHTO method) for depths up to 15' and for multiple offset distances. I then plotted the lateral pressures on a chart. (See pages 3 & 4 of attached PDF.) I noticed in the AASHTO commentary that this procedure is suited for a restrained top (at-rest pressure), which for this type of wall (flexible) yields very conservative results. I am assuming that I can reduce these lateral pressures by a factor equal to the ratio between the at-rest coefficient (3.25) and the active coefficient (0.31), which is about 3.25 / 0.31 = 10.5. Is this sound reasoning?
NOTE - the attached PDF does NOT show the adjusted pressures.....it still shows the at-rest pressures calculated with the AASHTO procedure.






RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
As for your proposed reduction, there is no reduction in surcharge load due to wall flexibility.
Mike Lambert
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
I would be surprised if they let you use a cantilever system, if they do, usually the deflection limits are very difficult.
EIT
www.HowToEngineer.com
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
Restraining the top of the wall or not would be the difference between the active pressure and at rest pressure. I`d expect this ratio to be much closer to 1.5 than 10.
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
Maine EIT, Civil/Structural.
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
I'm starting to wonder if the geotech consultant made a poor recommendation in regards to the wall type.......
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
EIT
www.HowToEngineer.com
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
I'm going to try and contact someone within CSX (engineering personnel) that can hopefully lead me in the right direction. I have a feeling that this wall type and general recommendation from the geotech wasn't vetted by CSX. Although the customer (power station) owns the property & tracks, I'm sure CSX would want to have input since they're using the tracks.
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load
For flexible walls (sheet and soldier pile) "1p" may be appropriate.
For semi-rigid, 1.5p.
RE: Temp Retaining Wall - CSX Cooper E80 Railroad Load