After taking on the new project, she was completely submerged by work.

submerged 是动词 submerge 的过去分词形式。submerge 由前缀 sub-（表示"在...下面"）和词根 merge（"浸入、合并"）组成，字面意思是"浸入下方"，引申为"淹没、完全覆盖"的意思。在这里表示"被工作完全占据"的状态。