df -lhT | head -n 31 | tail -n 10 | sed 's/[0-9]\+/& &/' | tr ' ' _

Display the long listing format of the files, with human-readable sizes, sorted by modification time, and show the first 31 lines. Then, show the last 10 lines, replacing each number with two copies of itself, separated by an underscore, and replace all spaces with underscores.
df -lhT | head -n 31 | tail -n 10 | sed 's/[0-9]\+/& &/' | tr ' ' _