生态脆弱矿区地表裂缝动态变化对土壤含水量的影响

Influence of dynamic variation of ground cracks on soil water content in ecological-fragile coal mining areas

针对我国西部生态脆弱煤矿区煤炭开采对土地生态环境的损害问题,以陕北生态脆弱矿区某矿为研究区,采用土壤水分速测仪(TDR)现场实测、统计分析相结合的方法,基于已有研究成果,研究分析采空区上方表层土壤含水量的变化与地表采煤沉陷动态地裂缝动态发育规律的关系。结果表明:采空区上方表层土壤含水量的变化与地表动态地裂缝的动态发育规律基本一致,当地表裂缝开始出现并开裂时,裂缝周围表层土壤含水量逐渐减少;当裂缝初次闭合时,表层土壤含水量也随之有小幅度回升;当裂缝再次开裂时,表层含水量也随之下降;随着工作面推进,后方裂缝闭合,表层土壤含水量也随之上升,且动态裂缝对表层土壤含水量有一定的影响范围,影响距离70 cm左右,距离地裂缝距离越近,表层含水量变化越明显,当距离超过70 cm时,表层土壤含水量基本不再变化。采动地裂缝对周围土壤含水量具有一定影响周期,且影响周期与动态地裂缝发育周期基本一致,土壤水分的变化与采动地裂缝的发育过程紧密相关,发现采动地裂缝的开裂与闭合对土壤微结构造成影响,进而影响土壤水分的蒸发与渗透,当采动地裂缝闭合后,土壤含水量将逐步恢复至采前水平。该研究具有开采工作面小尺度精细研究的特征,有助于生态脆弱矿区煤炭开采对土地生态的影响机制研究。

In view of the damage of land ecological environment due to coal mining in the ecological-fragile coal mining areas in western China,a mine in the ecological-fragile mining area of northern shaanxi was taken as the research area,TDR field measurement and statistical analysis were used,based on previous research results,the relationship between dynamic ground crack due to coal mining development rules and changes in soil water content in the mining process was studied and analysed.The results indicate that the variation of surface soil water content above the goaf is consistent with the dynamic development rules of dynamic ground cracks,soil water content around the crack gradually decreased when the crack emerged and extended;There is a corresponding slight rebound when the crack first closed;and the soil water content decreased when the crack extended again;With the working face advances,soil water content increases with the closure of the existing cracks. There is some influence extent of dynamic crack on the soil water content,the influence range is ea 70 cm,in other words,the soil water content changes obviously when approaching the ground crack,the soil water content basically remained unchanged when the distance from the monitoring point to the crack exceeded ea 70 cm,and there is a influence cycle of ground crack on soil water content,the influence cycle is consistent with the development cycle of the dynamic ground crack,the changes of soil water content is closely related to the development cycle of ground cracks,the cracking and close of ground cracks have certain impact on the soil microstructure,then affecting the evaporation and permeation of soil water,the soil water content could restore to the pre-mining level at last after the cracks close. This study is characterized by small research scale in one selected working face,which is helpful to the study on the influence mechanism of coal mining on land ecology in ecological-fragile mining areas.