Collapse mechanism of a gently inclined gypsum mine in Jiangsu.

Gypsum mines are generally exploited using room and column mining methods. Gypsum tends to become soft when encountering water, which often causes multiple geological disasters of ground subsidence. In Pizhou, Jiangsu Province, as of April 2023, a total of 35 ground collapses in 28 locations occurred, most of which were point shaped collapses with a diameter of less than 50m, and pumping type collapses are relatively rare. Taking the gently inclined gypsum mine in Pizhou as an example, the MatDEM method was introduced to conduct numerical simulation and mechanism analysis research. The results show that the pumping collapse of the gypsum mine caused groundwater to enter the mine pit, weakening the strength of the gypsum, causing secondary roof fall, blocking and ultimately stopping the channel collapse. After water filling, the overall stability of the goaf became worse, which is prone to induce secondary collapse. In response to the current situation, relocation and avoidance measures are proposed as well as monitoring, early warning, and engineering governance measures for prevention and control. [ABSTRACT FROM AUTHOR]