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Air Pressure Inside Metro Rail Tunnel for Cable/Pipe Support.

 
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ashutosh.jain
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PostPosted: Tue Apr 06, 2021 8:56 am    Post subject: Air Pressure Inside Metro Rail Tunnel for Cable/Pipe Support. Reply with quote

Hello Everyone,

I want to design a pipe /cable support inside Metro rail tunnel. My query is how much air pressure to be considered during movement of Train, I plan to consider this air pressure as wind load on support member. Is there any standard value which I can take or any tech reference anybody can provide, I will be grateful.

Regards,
Ashutosh.
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vikram.jeet
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PostPosted: Tue Apr 06, 2021 11:59 am    Post subject: Reply with quote

Not involved in metro tunnels

Since tunnel is open at both ends there is free flow of air in longitudinal direction. Transversely an air pressure of Cpi= -0.8p
may be taken as  internal air pressure based on IS875 (clause 6.2.2.8)on wind loads regarding horizontal cylinders.

But try see specific guidelines in metro literature on  net.

vikramjeet
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pvgraju
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PostPosted: Wed Apr 07, 2021 11:03 am    Post subject: AIR PRESSURE INSIDE METRO TUNNEL Reply with quote

Dear Sir,

When the train is moving with certain speed it is moving in a fluid called air.Horizontal force will be massxaccleration. Same force will be exerted on the air which will move in oppsoite direction of train movement. For excat reference you can refer some fluid mechanics reference with topic bodies submerged inside fluid.

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P.V.Gavarraju
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vikram.jeet
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PostPosted: Wed Apr 07, 2021 1:01 pm    Post subject: Reply with quote

Yes , Dear Er Gavarraju ji ,
When tunnel strech is having no train presence, the space will be occupied by air and Cpi =-0.8p trnseversly in line with Is 875. But when a train enters tunnel there is going to be additional pressure. In absence of any reference ,  as a logical view Cpi can be further factored by (x-sec area of tunnel) /(Balance tunnel area after deducting train x-sec). As regards inertia force of speeding train , since tunnel ends are allowing passage of air freely without any blockage, air escapes without exerting extra pressure , other than discussed above .
May be some more convincing view from some sefi member come.

Best wishes & rgds
vikramjeet
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vikram.jeet
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PostPosted: Wed Apr 07, 2021 3:45 pm    Post subject: Reply with quote

I think you are right in enquiring this aspect of aerodynamics in metro tunnel.  Request you to spend some time on internet and studies are available on this aspect.
Also see Railway tunnels  by ministry of Rlys  and transportation tunnels by MORTH. Some metro documents may also to be seen available on Google.

Yr vision is far sighted as a structural designer.

Best wishes

vikramjeet
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pvgraju
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PostPosted: Thu Apr 08, 2021 9:15 am    Post subject: METRO RAIL TUNNELS Reply with quote

Dear Sir,

Thank you for your suggestion. Very nice to hear from you.Definitely i will go through the references you provided and study further on this aspect.

Regards,

P.V.Gavarraju
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ashutosh.jain
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PostPosted: Fri Apr 09, 2021 7:53 am    Post subject: Reply with quote

Dear All,

Many thanks for your valuable feedback and suggestions. Will update once I find some references.

Thanks
Ashutosh Jain
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