After the inundation of shaft in Chengchao Iron Mine, large area collapse of developmentopenings caused serious influence on production.
程潮铁矿淹井后采准井巷大面积坍塌，给生产造成严重影响。
2
On the basis of these data, the main factors affecting the crack openings are found according to the basic principles on the emergence and development of cracks.