plate-loading test with a central hole

Air Admission to Main Shaft Central Hole

backward extruding by a disc with a central hole

CENTRAL HOLE

central hole method

central hole nozzle

central-hole nozzle

extruding the ingot backward by a disc with a central hole

bottom-hole test adapter

cross-hole test

curtain grouting test hole

double-hole test

down-hole test

needle hole test

Open Hole Test

percussion test hole

pin hole test

salt-water pin-hole test

scour hole test