风积沙区采煤沉陷地裂缝分布特征与发生发育规律

煤炭开发可能加剧对生态脆弱区环境的损伤,风积沙区地下煤炭开采对地表环境的影响主要是沉陷地裂缝,且目前的研究缺乏对地裂缝从发育到湮灭全过程的研究,笔者通过井上下相结合的空间坐标控制体系和自主研发的动态地裂缝监测方法,对补连塔12406综采工作面地裂缝进行持续动态监测,提出了边缘裂缝的分布规律和动态裂缝的发生发育规律及其与地质采矿条件之间的关系。研究表明:①动态裂缝超前于当前工作面向前发展,裂缝超前距与工作面日进尺量呈现明显的线性正相关,平均的裂缝超前距为10.359 m,超前裂缝角为近似垂直角;②高强度开采动态地裂缝的两侧无明显落差,裂缝的宽度值在采动过程中有显著的周期性变化,呈"M"型双峰波形,且第1个峰值明显大于第2个峰值,峰值比为1.4~3.8;裂缝发育周期T包含两个时长近似相等的"开裂—闭合"过程,约为18 d,在此基础上,结合地质采矿条件,建立了T的通用函数模型,表明动态地裂缝具有快速闭合的自修复特征,不需要人工修复;③边缘裂缝以"带状"、"O"形圈的形态分布在工作面开采边界的内侧,裂缝带宽为46~50 m,裂缝带整体向内收缩,临近工作面采动会减轻原有地裂缝的影响,减轻约40%,开采结束后边缘裂缝仍然存在,是主要地表环境损伤区和重点人工修复区域。

Distribution characteristic and development rules of ground fissures due to coal mining in windy and sandy region

Coal mining might cause serious environmental damage in ecologically fragile region.In sandy and windy region，ground fissure is the most typical characteristic of ecological damages caused by underground coal mining.However，few works and reports are related to the generation and whole development process of ground fissures caused by high tension and rapid caving mining.Through the united space coordinates control system at surface-underground，a comprehensive observation method was invented to monitor ground fissure on the No.12406 working face of Bulianta coalfield，distribution characteristic of marginal fissures，genesis and development rules of dynamic fissures and their relationship with mining geological conditions were revealed.The results show that：① Dynamic fissures always develop ahead of the current working location，the crossover distance has a significant positive linear correlation with size of daily footage.The average fissure crossover distance is 10.359 m and advance angle of break is approach to vertical angle.② Under the high tension and rapid caving mining，dynamic ground fissures havn’t obvious heads in vertical direction，those widths had similar cyclical changes during the mining process and present ‘M’ type with two different peaks.The first peak(maximum width)is 1.4-3.8 times of the second one.The life-cycle of a dynamic fissure is 18 days，including two cracking-closure processes with similar duration.On this basis，a common function model for the life-cycle was established based on mining and geological conditions.It indicates that dynamic fissures have fast ‘self-healing’features and manual repairmen might not be necessary.③ Marginal fissures occurrs in strips and the ‘O’ shape inside of boundary working face，and the width of strip of marginal fissures is about 46-50 m.If the adjacent coal face excavates，the width of the strip of marginal fissures in this side will be narrowed 40% due to the double disturbance.The distribution region of marginal fissures will exist long time and need manual restoration.