Slightly different office to most
Assuming the wall of the tunnel where the mount is attached in the first photo must be concrete. How stable is that location based on differing pressures on the other side of the tunnel wall?
Very cool.
I believe I saw a report for an accelerator project that quoted measurements as x,xxx.xx millimeter. (Or if it was in Europe, x.xxx,xx mm.)
Yeah I believe the article I read was referencing sub-millimetres think one was using micrometre as units of measurement when positioning the actual accelerator (don't quote me on that though)
Yeah London has quite a challenge threading new tunnels amongst all of the existing tunnels and building piles, even getting the machinery down to start the tunnelling.
Assuming the wall of the tunnel where the mount is attached in the first photo must be concrete. How stable is that location based on differing pressures on the other side of the tunnel wall?
These brackets/mounts are pretty solid. Most pressure will be from the TBM its self as it advances forward. The void behind rings get grouted and this allows the pressure from the TBM to be transferred to the surrounding earth.
Those brackets (picture 1) are temporary and get moved forward with the TBM as it advances anyway. We place more permanent ones further behind and use these to traverse from outside regularly up to the temporary ones to check/update their coordinates.
way cool
Looking good, I have spent some time working on tunnels also.
I am interested in learning more about how other people set fiducials.
I have heard that when you order a Heerenknecht machine equipped with VMT that the spigots come installed and that you just need to survey the machine and fiducials and drop the NEZ into VMT.
I have used TACS, ZED, and Enzan but never VMT.
Thanks for sharing, it looks like the operations are clean and safe! Good for you guys for keeping an operation that you can take pictures of without it looking like a disaster.
Looking good, I have spent some time working on tunnels also.
I am interested in learning more about how other people set fiducials.
I have heard that when you order a Heerenknecht machine equipped with VMT that the spigots come installed and that you just need to survey the machine and fiducials and drop the NEZ into VMT.
I have used TACS, ZED, and Enzan but never VMT.
We're using CAP as its a subsidiary, most people at work say VMT is really good (I've not used it).
If you look at (picture 2) you can see some retros which we used. CAPs own surveyors went to HK factory in Germany and surveys a bunch of retros they placed on the H-frame to coordinate them to the machine.
Once the TBM was reassembled on site, we welded reference prisms on then surveyed those with the retros. CAP then used the retros to coordinated the offset values for the prisms relative to the TBM from their survey at HK.
Thanks for sharing, it looks like the operations are clean and safe! Good for you guys for keeping an operation that you can take pictures of without it looking like a disaster.
I try not to take pictures of all that! ???
Very cool. Please keep us updated as "niche" surveys like this are always fun to read about.
Excellent! Thank you for sharing!
No gyro used? How long was your start reference line? I did some tunneling before and was always anxious to know if they would show up where they needed to be.
Not these kind of tunnels but 2m diameter in curbs for a few hundred meters. Exciting but stressful jobs
I did some gyro azimuths for a pair of hydro tunnels in Peru, they had me come in when they were getting close to breakthrough, drilling from both ends. I think one was 22 km and the other a bit less. Had a bit of a water problem...
We had to ride in the mine cars to get to the face, about 45 minutes each way
Here was their "low-tech" TBM guide target, as long as the laser was inside the hole, they were online
I had to observe a surface line to calibrate, on triangulation pillars
The TBM was nowhere as clean looking. They actually got one of them stuck, and had to bring in another one to clear a path to get it out.
They sent me pics when they broke through, not sure what I did with those.
