[300.5(F)]. Don't use items that can present a
threat of physical damage to the cable. The NEC isn't precise about
what needs to be excluded; common sense prevails. If you adhere to
the principle, instead of seeing what you can get by with, you'll
satisfy the code.
[300.5(J)]. The movement of earth. That includes,
but is not limited to, movement due to settlement or frost.