摘要
当煤系地层中赋有断层时,煤层开采易造成断层带滑移失稳,导致地表形变出现异常响应.为了揭示上述异常响应机理,本文基于FLAC^(3D)软件,建立了逆断层下盘开采数值模拟模型,模拟研究不同工况条件开采后地表沉陷的时空演变特征.实验结果表明:断层倾角变化时,地表异常沉陷出现的位置与断层露头处密切相关,随着断层倾角的增大地表最大沉陷值也随之增加,且地表沉陷曲线的对称性经历了接近对称-不对称-接近对称的变化.断层落差变化仅改变岩层的产状分布,地表沉陷并未出现明显的异常响应,但在断层的影响下地表的移动范围和超前影响距均会减小.薄松散层下开采,断层对地表沉陷响应起着主导作用,厚松散层下开采时,断层与松散层对地表沉陷响应的作用相当,巨厚松散层下开采,松散层对地表沉陷响应起着主导作用.结合摩尔-库伦破坏准则,定义断层带上剪应力与正应力的比值τ_(T)用来判断断层是否活化,断层倾角越小断层越容易发生活化,浅埋断层比深埋断层更容易发生活化;松散层厚度经历薄-厚-巨厚的变化时,断层露头处的开始活化的时间表现为快-慢-快,而埋深大的断层较稳定,不易发生活化.
When there are faults in the coal measure strata,the coal mining is easy to cause the slip and instability of the fault zone,resulting in abnormal response of surface deformation.In order to reveal the above abnormal response mechanism,based on FLAC^(3D)software,a numerical simulation model of reverse fault footwall mining is established to simulate and study the temporal and spatial evolution characteristics of surface subsidence under different mining conditions.The experimental results show that:when the fault dip angle changes,the location of abnormal surface subsidence is closely related to the fault outcrop.With the increase of the fault dip angle,the maximum surface subsidence value also increases,and the symmetry of the surface subsidence curve changes from nearly symmetric to asymmetric to nearly symmetric.The change of fault fall only changes the occurrence distribution of strata,and the surface subsidence has no obvious abnormal response,however,under the influence of faults,the range of surface movement and the leading influence distance will decrease.When mining under thin loose layer,fault plays a leading role in response to surface subsidence.When mining under thick loose layer,fault and loose layer have the same effect on response to surface subsidence.When mining under super thick loose layer,loose layer plays a leading role in response to surface subsidence.Combined with Mohr-Coulomb failure criterion,the ratio of shear stress to normal stress on fault zone τ_(T) is defined to judge whether the fault is activated or not.The smaller the fault dip angle is,the easier the fault is to be activated,and the easier the shallow fault is to be activated than the deep fault;When the thickness of loose layer changes from thin to thick to very thick,the activation time of fault outcrop is fast slow fast,while the fault with large buried depth is stable and not easy to be activated.
作者
罗锦
郭庆彪
陈红凯
王小兵
王亮
张义颖
LUO Jin;GUO QingBiao;CHEN HongKai;WANG XiaoBing;WANG Liang;ZHANG YiYing(School of Spatial Informatics and Geomatics Engineering,Anhui University of Sciences and Technology,Huainan 232001,China;State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Huainan 232001,China;Sinosteel Maanshan Institute of Mining Research Co.,Ltd.,Ma'anshan 243000,China)
出处
《地球物理学进展》
CSCD
北大核心
2022年第3期1280-1291,共12页
Progress in Geophysics
基金
国家自然科学基金项目(51904008)
安徽理工大学研究生创新基金项目(2021CX2143)
安徽省重点研究与开发计划项目(202104a07020014)联合资助。
关键词
地表沉陷
逆断层
下盘开采
滑移失稳
Surface subsidence
Reverse fault
Footwall mining
Slip destabilization
