All LB
Looks like a variety of cutting techniques to me.
The cut slats appeared to be 1/8-3/16 sidewall, which could be attacked by concrete saw, angle grinder, torch, plasma cutter, sawzall, or circular saw with abrasive wheel.
The sand filled posts would make it harder to cut with a torch, but could be overcome by drilling a hole to let the sand out. Best to leave some good size rocks low in the tube to prevent that.
If I was trying to cross, I'd want a battery powered sawzall, angle grinder, replacement blades, and at least two 5Ah batteries. I'm pretty sure I could get through it with that.