They made joints in stone keeping the lintels in place horizontally using a tongue and groove joint and subsequently fixing the upright and lintel with a ball and socket joint or mortice and tenon.
The geological condition is complicated and varies often. Using the method of pre-support through hammering wedge, the cave mouth digging work of No. 640 main transportation channel was successful.
The geological condition is complicated and varies often. Using the method of pre-support through hammering wedge, the cave mouth digging work of No. 640 main transportation channel was successful.
