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