MSE Wall Design 2

[Jean_Wong]

Good Day!

I am designing MSE wall for a railway project. Some parts of the railway are elevated and need MSE wall because there are roads on the sides.

How do I consider the soil reinforcements when checking for overturning, sliding? Should I consider the mse wall soil reinforcement length just like retaining wall where the vertical force from the soil on top of the heel resists the overturning & sliding moment? Or are there different parameters such as friction, etc?

I'd also like to ask for sample computations/references if you could recommend any.

Thank you very much!

 

[oldestguy]

I'd do a Google search. Some designers uses Rules of Thumb, but take a look at the many references that come up.

 

[fattdad]

there are references by the National Highway Institute, FHWA and National Masonry Association that provide design guidance on stability of MSE walls. In general when dealing with external stability, the reinforced zone is considered a stable mass and you just look at the free body diagram acting on the overall shape. That would provide an opportunity to look at the sum of forces in the horizontal as well as the sum of the moments about the toe or heel. The weight of the gravity mass providing the normal load on sliding resistance.

Safety factors of 1.5 are typical for these modes of failure.

Global stability (something different from overturning and sliding) is related to slope stability. This is a necessary design condition.

f-d

ípapß gordo ainÆt no madre flaca!

 

[BigH]

Depending on where you are - BS 8006 is the British Code of Practice for MSE walls. You can buy the reference if you don't have it. A few references:

http://nptel.ac.in/courses/105106052/downloads/Lecture-11.pdf

http://textofvideo.nptel.iitm.ac.in/105106052/lec11.pdf

http://www.geosynthetica.net/naue-mse-design-software-secuslope/

(no affiliation with this company)

 

[Jean_Wong]

Thanks for the tips!

Is it correct that I add a horizontal component from the train by multiplying it with Ka (with factors for strength 1, extreme 1, extreme 2) when checking for sliding and overturning?

I also added Pir which is the horizontal force from the inertia of mass of the reinforced soil.

 

[Doctormo]

Railroads have there own way of doing things in the US. They were around before highways.

Where is the railroad in proximity to the wall face? Given the huge loads involved with railroads, the analysis may be much more complicated that a simple Ka relationship.

You are looking at Pir which is a seismic factor. This could be a complicated analysis and should be looked at by someone skilled in MSE wall design.

 

[Jean_Wong]

@Doctormo

My senior would check my design after I'm done but she has other things to check so I want to keep errors minimum. Aside from AREMA, what are other good references?

 

[Doctormo]

Union Pacific RR has some information from their viewpoint.

https://www.up.com/cs/groups/public...up_pdf_nativedocs/pdf_up_str_temp-shoring.pdf