(Preble County, OH)--Heavy rain has forced the closure of a Preble County highway.  State Road 320 just south of New Paris was not flooded Tuesday morning, but it had been affected by a mudslide.  A portion of a hillside gave way Monday afternoon close to U.S. 40 and had the highway blocked Tuesday morning.   Clean-up is expected to continue throughout Tuesday morning, but 320 is expected to re-open later in the day.