Effect Of Aquifer Structure Variation On Permeability Under Coal Mining

Coal resources of high strength large-scale mining,for quick take-off of China's economy provides a steady flow of energy,but also on the natural environment will inevitably produce great damage,resulting in mining ground subsidence,lower groundwater levels,groundwater resource shortages frequency of such phenomena have occurred,but the root cause of this phenomenon is the result of coal mining of overlying strata structure variation,changing the permeability of the variable region,the local groundwater flow direction changes,affecting the groundwater circulation.From the perspective of hydrogeology View on structural variation of overlying strata mining-driven issues that structural variation is actually overlying rock containing impermeable layer structure changes in mining driven by the formation of a new-containing impermeable layer composition relations and the new structure of the aquifer permeability,aquifer also will be changed.This is leading to changes in groundwater flow field,the root causes of groundwater resources in distribution.Taking Changzhi basin core mining geological prototype using similar material simulation experiment,field pumping test,the upward slant hole injection experimental research by means of changes in the aquifer spatial structure after mining,after variation aquifer characteristics,etc.in-depth analysis this study area mining water cycle,groundwater resource allocation is important.(1)According to geological data mining generalization stratum structure,the establishment of similar material simulation test model to simulate the structural variability of overburden rock after mining.The study found overlying rock variation area containing the original structural features impermeable layer was completely broken,new structural features become the main features and structural characteristics in different regions of different,specific performance is compacted in a closed area perpendicular fracture network based,and coal wall near the large opening angle of the main fissure,fracture horizontal separation area,better connectivity,caving is a large band gap.(2)based on field research data show that the surface in some areas within the mining area to crack a large area of ground subsidence in some areas well collapse,the worst areas appeared villagers collective relocation phenomenon,according to monitoring data show that in the absence of significant changes in the area of surface also changes,can be seen on surface coal mining has had an impact on the unconfined aquifer,therefore,within the mining area selected pumping test point 19,the study found in the mined-out area of unconfined aquifer permeability are affected by the impact of coal mining increasing trend.(3)Using the upward slant hole injection test methods for seam roof with regional variations confined aquifer aquifer permeability studies,the researchers found that the coal wall at the largest unit of time stable water injection,water injection and compaction area is relatively small,but injection volume far greater than the initial stress state,indicating that variation in aquifer permeability is better than non-variant aquifer,aquifers variation in flooding after having zonation.