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Here are the 3 Engineering options to solve the Kolkata Metro East-West line mess
Telegraph India report that engineers from 3 countries tackle the problem in Kolkata's East-West tunnel boring. During the boring, Tunnel Boring Machine was overwhelmed by water after hitting a aquifer and then followed by subsidence of earth which in turn caused the most problem of hauses over the boring crack and get demolished. Left 500 people homeless.
Engineers now evaluate 3 options:
1- The TBM boring the second tube will make a U-turn and also bore the problem tunnel.
2- At Bowpazar where the problem TBM is stuck, a shaft will be digged and a new boring machine will be lowered
3- At a place less crowded than Bowpazar most likely between Bowpazar and Sealdah a new shaft will be digged and new TBM will be lowered there.
Detail:
https://www.telegraphindia.com/states/west-bengal/the-way-forward-for-east-west-metro/cid/1705207
My other posts on subject:
India: How are the Kolkata East-West Line Tunnel Engineers fighting the TBM in water cavern problem?
India: Water tore Kolkata East-West Metro tunnel-boring machine seal: Engineers
I am certain all agree that the best option against a problem is not having it at the first place. I mean, to take measures to prevent it from happening.
While studying I stumbled upon two more fine documents from ITAtech, the technology arm of ITA.
I was wondering, whether the construction company did its homework before starting the boring? If they followed this guidance document of ITAtech, would they still have problems?
ITAtech Publication: Geophysical ahead investigation methods / Seismic methods
and if the tunnel boring machine that they used was a pre-used one, would they still have the`"seal problem" if they read this ITAtech document on re-assembly of TBMs?
just asking...
@coert klomp it was a refurbished TBM which was previously used in Delhi metro
@T.Altman, your profile says ' MSc Student in Civil Engineering with special interest in tunneling'. Did you ever work in a tunnel?
Theory is different from real work. In real work you have no time to think of every option, You can not stop. You have to do right or not. You will learn.
Dear Santiago, I have been to tunnels under construction but No, I have never actually worked in one. What is your point?
I don't have to be a cook to know that to be able to cook, first you need to learn cooking. Those 2 docs of ITAtech are part of an excellent preparation for tunneling, rather than delving into it without preparation and then hoping the best and when the sh**t hits the fan, running amok. It is not the tunnel engineering I have in my mind.
@T.Altman you are reaching fast conclusions from what I write. My point is this. Maybe you read the books beforehand or got training. When the problem hits you underground, it hits you super fast and hard. In that havoc, you have to act super fast/ You do things fast and your reaction is always textbook quality. Because we are not programmed robots.
Dear Santigo. My message was about a simple fact: If you do a proper geological survey and if you make sure your TBM is up to the task, you might prevent some problems from occuring. I hope we agree on this.
By example: Samples are taken from the depths of the mountain in Arkansas, to determine "if a tunnel boring machine can hollow out a 5-foot diameter corridor from the base of the mountain's southern slope to an inlet east of Lake Ouachita's main channel".
https://www.hotsr.com/news/2019/sep/22/drillers-give-city-inside-look-at-blake/
cover tunnel photo by: Matt Brown from London, England / CC BY
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All these options hint a tunnel boring machine screw up. Obviously the TBM is damaged beyond repair. Either because of bad operation or because it was crap in the first place.
Can anbody comment on the brand/model of the TBM and whether it was a new one or a renovated one?