Caulking should not be used in lieu of weather closure, an epoxy set anchor should not be placed in tension, and existing sub-soils should be proof rolled.
This was a design error before any error first and foremost.
If for some highly unlikely reason it was necessary, then special care in the specification of the material including a sample test and frequent field tests should have been specified.
Often times the trade contractor in the field has three days to order out the material needed for a procedure where the designer has three years to select and specify it.
Don't get me wrong, I've seen small plumbing contractors paint a fitting a bright copper color to try and make a stupid substitution out os stupid attempts to not have to stop work and pay for the right part, but this smacks of the threaded rod design on the Hyatt Regency Skywalks collapse.
Construction is not my field, but I have built a lot of stuff to last, and I do know epoxies. Your points about sample collection and field test are spot on.
To me this situation looks like an afterthought. Either it’s a bandaid on another design issue, or somebody decided to dole out some extra steel and concrete contracts.
BTW, one of the biggest factors I’ve seen in epoxy joint durability is thermal cycling. Under a car’s hood these can be extreme and frequent, but in a tunnel are they considered a factor? Is accelerated life testing used in design qualification?
How do you explain the roof control plans of most underground mines?
Bzzzt. Wrong. Happens all the time, by proper design. There are lots of products specifically desigened to do just this, but the key is to get the embedment length long enough so the pullout strength is higher than the compressive strenght of the concrete. It's not easy to do, as everything has to be spot on. Mechanical anchoring systems would have been much beter, but epoxy wasn't a definite no, as long as it had been properly specified.
I’m not an engineer, but I could tell that there would be problems of some sort with this project when I visited Boston as a tourist about three years ago. At that time the project was already years behind schedule and billions over budget. Despite this, the downtown dig was still an open trench with lots of braces and cement forms everywhere. I was there for three days and never saw more that two dozen workers or so, many of them supervisors going in and out of construction trailers. My impression was one of a gravy train for the unions with all involved determined to move it forward as slow as possible so the project had turned into a job for life. I suspect that their amount of overtime took precedence over quality of work concerns.