While building an igloo for kids the other day I thought how stable the whole thing becomes when you stack the final blocks, and the arched shape is complete. Then thought about masonry. It occurred to me that a standalone arch should hold up pretty well, even without the surrounding dome. Something like this:
but made of snow:
The test arch is just two feet tall, snow is sticky stuff at 32F and plastic support salvaged from trash is really flimsy. But it was promising. The arc stood fine after removing the plastic and it was dead easy to build it. So next one to one scale tests.
My idea is to shovel and stomp a pile of snow, let it harden for a while and then cut lots of blocks (that's how the igloo was constructed, along guidelines of BPL article by Tad Englund). Then stack one arch, move the support a bit, stack a new arch, move the support ... and thus start forming a snow tunnel.
I hope it would be very fast and easy to build. While igloo is quite limited in size and shape this method would also allow long tunnels, curved tunnels, tunnel crossings etc.
Weather is going to be wet for few days and snow will be way heavier than ideal for this so I'm going to have a week to come up with a good design for the support. Any suggestions about: