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Anonymous Poster

About Shotcrete

07/10/2008 11:21 PM

Hi everybody!!!

We're undertaking tunneling works here in the Philippines and we are encountering a formation of compacted sand which disintegrates when surface moisture evaporates. The problem now is how to apply shotcrete on the tunnel face since sand is not capable of holding the weight of the applied shotcrete. Or is there any alternative tunnel surfacing that can be applied that is at least same or lesser cost than shotcreting.

Thank you

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Commentator

Join Date: Jan 2008
Posts: 67
Good Answers: 6
#1

Re: About Shotcrete

07/12/2008 12:05 AM

Need more info to get more advice

Always a problem -

Pick a typical section - Try thick corn / rice starch / white-glue

Problem will be that the trapped water behind the im-/low pervious unit will build up so you may also need to get a drainage tube into the formation

Careful that you don't dry out the formation before you get the liner in

Be very careful on any dewatering by well-points and water wells.

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Commentator

Join Date: Oct 2006
Posts: 69
Good Answers: 3
#2

Re: About Shotcrete

07/12/2008 12:09 AM

Hydro-active urethane injection

tesla-was-right@hotmail.com

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Guru

Join Date: Mar 2008
Location: Sebring, Florida
Posts: 923
Good Answers: 25
#3

Re: About Shotcrete

07/12/2008 10:57 AM

Your engineering estimators likely selected the least expensive method for this construction from the very beginning. Anything else that you attempt will almost certainly cost more. Look at the most obvious issue. How would you have designed this work if you knew that this issue was going to exist, through out the work in progress.

I can assure you that there will be NO CHEAP way out, that will not be creating a weak zone in the finished work. Ex; bridge fails in Minn. U.S.A.: many people lost lives.

TMF

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The only problem with common sense, is that not very many people have it, or know how or when to use it.
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Commentator

Join Date: Jan 2008
Posts: 67
Good Answers: 6
#4
In reply to #3

Re: About Shotcrete

07/12/2008 12:28 PM

Engineering estimates should be based on the least expensive methods, problems arise when the engineers don't provide adequate methods or estimate methods based on inadequate field information - ALWAYS a problem in mining and tunneling - then add inadequate contingencies based on complex geology...etc.

Hand mining and NATM are the cheapest methods - however - the technology transfer of NATM is not the problem...management transfers are also required...we did an estimate for a chiense transit tunnel and the HM by 4000 workers was similar in cost to the NATM and both were 25% of doing it with Shields...However, the NATM required assign of authority/power/money etc/ to the face foreman or supervisor/engineer and the assumption of such powers by the field foreman or supervisor/engineer and that was the rubbbbbbb.

We did a similar project in Malaysia and did MonteCarlo analyses which showed the very high risk of overruns when your dealing with geological and other field conditions. Choose the least expensive and then put adequate contingency on it (100%) for Hand Tunneling vs Shield.

Tom

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Active Contributor

Join Date: Apr 2008
Posts: 20
#5
In reply to #4

Re: About Shotcrete

07/14/2008 10:06 AM

FINE SILICA+CEMENT+ CALCIUM SILICATE PASTE/SLURRY IS ONLY THE LESS EXPENSIVE SOLUTION,THIS MATERIAL IS MANUFACTURING IN INDIA BY---

KOHINOOR MORTAR & MATRIX

email-amarkantakdevired@yahoo.co.in

Tel ;+91 761 4007106,Cell- 09827392958,09300115319

FIRST SODIUM SILICATE IS CONVERTING IN TO CALCIUM SILICATE.

FOR MORE STRONGER ADHESION RESULTS YOU CAN USE POTASSIUM SILICATE INSTEAD OF CAL.SILICATE,WITH OTHER INGREDIENTS.

ALL GRADES ARE MANUFACTURING BY ABOVE SAID CONCERN.

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