。
She collapsed to the floor as if crumbling.
Literal
She [topic-は] floor [onto-に] crumble [in a manner like-ようにして] fell.
ようにして adds manner: 'as if crumbling, in a crumbling way.' 崩れる (くずれる, 'to crumble, to collapse') provides the simile — her fall wasn't sudden but a gradual giving way. 倒れる (たおれる, 'to fall down, to collapse') is the main action. The combination paints a vivid physical image.