huangyhg

underground parking adjoining railroad
we are planning a 4 level underground structure that would run approximately 20 feet from a rail line. issues would be what type of shoring would be needed during construction. looking for professionals that have tackled this issue please give any advise you can.
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you have to use the highest rail loading as a surcharge on the soils. talk to the railroad for help. they don't want to lose a train in your hole.
richard a. cornelius, p.e.
the first project that i designed out of college was one very similar to yours.
i had a retaining wall that was about 20 feet high with railroad tracks that were nearly 20 feet away. as stated above, use track load as surcharge and be conservative. that design still standing well after many years of service. trains go by many times a day loaded with coal.
you need to review the contractor’s ways and means during construction to reduce possibilities of excavation slope failures. i would ask them to prepare an excavation plan (and shoring if need be) and have it prepared by specialty engineer who is experienced in this type of construction.
i think you will be ok once you use the right surcharge.
regards,
lutfi
thank you lufti
can you please tell me location of the project you referred to.. always good to get an example when we discuss with railroad.
you need to get the railroad's sheeting and shoring specifications. these specs will tell you about the required surcharge, what needs to be sheeted vs. open cut, soldier beams and lagging vs. steel sheet piling, etc. different railroads have similar but different specifications.
the project was in southern west virginia. i have some pictures during and post construction. let me see if i can dig them out and scan them for you.
the railroad company was norfolk and western at that time. it has changed since then to norfolk southern corporation, i think. my experience with rail road companies is that they are worse than government agencies. they have too much bureaucracy and paper work. i dealt with a railroad company in florida once in the 15 years and it was not a smooth sailing. they are well established and have stern rules in place.
regards,
lutfi
once you have accurate rr loading information, as lutfi says, stay conservative on calculating forces on the temporary shoring. the old, simple ways, such as coulomb-rankine theory, should provide an extra safety margin that may come in handy for unanticipated conditions.
loading is not always as predicted. this is a photo of a (permanent) 10' deep, braced steel sheet pile drainage canal adjacent to a railroad spur on steel mill property (the track is just out of the picture on the right). we had the contract to repair this damage, under what would be called a design-build contract today - the engineer-of-record paid for the repairs since he had underestimated the lateral forces.

slideruleera,
more details please. the sheeting walls still look fairly straight yet the cross braces have bent upward. there seems to be a good number of braces, fairly close together. the track is not visible so i would think that it's not too close to the wall. did you determine the cause of the failure?
note the cross beams are connected to two i-beams at each side of the sheet piles. looks like both i beam at right forground and some of the cross beams have elastically deformed.
slideruleera - great picture!
most railroads will require a cooper 80 loading. depending on the railroad, the load will be somwhere between 1.25 and 2.0 ksf applied over the width of the tie (8-8.5ft). however at 20 feet from the track, the effect of the surcharge will be greatly diminished and proably won't have a great effect on the design.two things to consider is track settlement and tie backs. if you use soldier pile and lagging, be sure it is done by an experienced comptent contractor. a large slough at the bottom of the excvation (these things never happpen excpet when you are just finishing) can cause settlement of the tracks. it is always good to survey them before and after. also a 20 ft cut will require tie backs which will be 40 to 60 ft (or possibly more) so you need to talk to the railroad about their requirements for the tiebacks.
peinc - the track was about 20' from the canal. beyond the track was the steel mill's slag pile, which was being continuously broken up for rail shipment. this was accomplished by picking up & dropping a solid steel ball (about 4' diameter) with an electromagnet. here is the ball in free fall
what the engineer-of-record (a respected, national infrastructure firm) had not considered was the liquefaction of coastal soils caused by the steel ball impacts (you could not only feel the impact, but also see everything shimmer; real "man-made" earthquakes). the sheet pile walls had moved together a few inches over 7 years.
three failure modes:
1. horizontal struts buckled when the wale webs yielded & the strut/wale welded connection held.
2. struts remained straight when the wale webs yielded, but the strut/wale connection failed.
3. struts remained straight when the wale webs crippled.
here is a photo of repair work in progress
repairs amounted to replacing both the w6 struts and lightweight w12 wales with beefed-up, used hp 12.
nothing fancy, just a brute-force, conservative solution - as being suggested for rbarn's temporary shoring.

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