{HEAD ~ The backfill soil} must be provided into {TAIL ~ the inner region} of the hopper 110 and must continuously fall through the backfill sleeve 126 which is arranged along the full longitudinal length of the backfill hopper 
{ HEAD ~ The backfill soil } must be provided into { TAIL ~ the inner region } of the hopper 110 and must continuously fall through the backfill sleeve 126 which is arranged along the full longitudinal length of the backfill hopper
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH