First, apologia for offending anyone. I honestly thought Why use 'piled-up earth supporting a banner for indicating official rank'? was on topic for history!
Second, how can we salvage this question? Closing and deleting feel like a shame, because the comments answer my question well! You have my consent to edit and improve my question!
1. Please show me drawings, illustrations of this usage?
2. I have difficulty imagining or picturing why Chinese officials used "piled-up earth supporting a banner for indicating official rank"?
By definition, "piled-up earth" is earthy, whose synonyms in English are bawdy, crude, lowbred. Obviously, any Chinese official would hate to be seen as "bawdy, crude, lowbred"! Thus why didn't Chinese officials use posher materiel to support their banner indicating their rank?
I scanned Christopher Seeley's The Complete Guide to Japanese Kanji (2nd edn 2006), pp. 518-9.