These files use OGC GeoSPARQL literals for geometries.
You find scripts for the conversion to Virtuoso geometries under:

    http://downloads.linkedgeodata.org/releases/scripts/ 


Example usage:

    bzcat your-file.sorted.nt.bz2 | ./convert-virtuoso.sh | ./discard-corrupted-geometries.sh > your-file.virtuoso.nt