surmonter

I'm confused about the use of "surmontés de" in the following text.

Dans les campements de fortune, les sinistrés n'ont que quelques piquets surmontés de bâches mal attachées et trempéespour se protéger.

I think it means "quelques piquets étaient surmontés par des bâches mal attachées", but i don't understand why the author uses "de" instead of "par", and why there isn't an artcle (like des ou les) before "bâches"

Some verbs just take the preposition "de" . Surmonter de means to be covered by/with - just like "couvert de".

surmontés : here, covered up, caped.

thanks for your explanation. but why there isn't any article words before bâches?I think in french there is always an article word before the noun.

surmontés de = surmontés par des