山东省平邑左庄石膏矿区非采空致塌机理与治理方法

Mechanism and Management of not Excavated Areas Subsidence in Zuozhuang Gypsum Mine in Pingyi County of Shandong Province

平邑左庄石膏矿区曾发生过3次地面塌陷,但井下实地调查发现,该矿区地面塌陷并非地下采空塌陷波及地表后而引发的地面塌陷。根据矿区地质环境条件、采矿方法及井巷工程布置等因素,分析认为地面塌陷原因是矿山布置的第一开采中段未预留出足够的顶柱厚度,致使井下回采时揭穿矿房顶柱接触到上覆第四纪松散盖层,第四纪孔隙水携带泥砂泄入矿坑发生潜蚀作用,在矿房顶柱与第四纪松散盖层之间形成"天窗式"砂漏,第四纪松散盖层中逐渐形成土洞,土洞扩大并塌陷后引发地面塌陷。

Three surface subsidence have occurred in Zuozhuang gypsum mine in Pingyi county. According to underground survey, these subsidence are not caused by the mined- out collapse. According to geological and environmental conditions, mining methods, the layout of alley and other factors, it is regarded that subsidence has been caused by not enough depth of the top columns in the first mining section. Thus, loose covering beds of the Quaternary system and in the middle of working out section become too thin. In the period of underground mining, the top columns have been penetrated, and the loose covering beds of the Quaternary system have been connected. Quaternary pore water carried sand to mines, and induced potential erosion, and formed ＂sky light＂ type hour glasses between the top columns in worked out sections and the loose covering beds of Quaternary system. Thus, soil caves in the loosing covering beds of Quaternary system have been gradually formed, enlarged and caused surface subsidence.