程潮铁矿塌陷区周边地表变形扩展规律研究

Study on ground deformation around collapse zone in Chengchao iron mine

地下采矿引起的地表变形规律的分析,能为地表变形范围的圈定和矿山安全生产提供指导。以程潮铁矿西区为例,依据近11 a的监测成果,结合岩层移动机制,对塌陷发生以后地表变形与扩展规律进行分析,并根据所收集的水文地质与气象资料,探讨降雨对地表变形与岩层移动的影响。研究结果表明:塌陷发生以后,地表变形不断向外扩展,从塌陷后至2008年9月,地表变形以塌坑为中心,在上下盘均匀扩展;到2014年12月,地表变形以采空区为中心,下盘变形程度明显大于上盘;地表变形呈漏斗状,并随着时间的推移,沉降漏斗的深度和范围不断扩展。在SN方向上,沉降漏斗在北部扩展大于南部;在EW方向上,沉降漏斗中心不断向东移动;根据岩层移动机制,将深部岩体变形区域分为倾倒滑移区、倾倒拉裂区和弯曲变形区,不同区域测点变形曲线有不同特点;在倾倒滑移区,地表在出现加速变形阶段后变形一直保持较大速度增长,在倾倒拉裂区,地表变形特征为加速变形后又恢复稳定,弯曲变形区,地表变形保持较小速率稳定增长,采空区周边测点在地表发生再次塌陷前有明显的变形加速;地表变形与降雨量和降雨持续时间有关,在1 a中单月地表变形有2个峰值,分别在2~3和5~8月份。

Analysis of surface deformation induced by underground mining can provide guidance for figuring out the range of surface deformation and guaranteeing the safety production of the mine.The west zone of Chengchao iron mine was investigated through the comprehensive analysis of monitoring data from 2006 to 2017 and the trend of ground deformation after surface collapse was studied.The effects of rainfall on the surface deformation and rock movement were discussed based on the collected hydrogeological and meteorological data.The results show that the surface deformation had been extending constantly outward since the ground collapse.From the moment of ground collapse to the end of September 2008,the surface deformation expanded with the collapse area as the center,and evenly expanded in the hanging wall and footwall.However,in December 2014,the footwall deformation proved significantly greater than the hanging wall with the center of deformation area shifted to the mined-out zone.The depth and extent of the funnel-shaped surface deformation were expanding unceasingly with the time passing.In the north-south direction,the expansion of deformation funnel in the north was greater than in the south.In the east-west direction,the center of the collapsing funnel kept moving eastward.According to the mechanism of rock movement,the deformation area of deep rock mass is divided into the toppling-sliding zone,the toppling-cracked zone and the bending deformation zone.In the toppling-sliding zone,the deformation of the surface is maintained at a large speed after the accelerated deformation stage.In the toppling-cracked zone,the surface deformation restores the stability after the accelerated deformation,and the deformation of the bending deformation zone is maintained at a small rate.The monitoring points around the mined-out area have obvious deformation acceleration before the surface collapse.Surface deformation is related to the rainfall intensity and rainfall duration,which has two peaks in February to March and May to August respectively.