5.obstruct (vt.)
①阻挡、阻塞、遮断(to block a road, an entrance, a passage, etc. so that sb/sth cannot get through, see past, etc.)
②(故意)妨碍、阻挠、阻碍(to prevent sb/sth from doing sth or making progress, especially when this is done deliberately)(=hinder)
本诗中选用意思①