Similar Experiment Research On Overburden Movement And Aquifer Failure Caused By Mining On The Condition Of Different Mining Depth

As a thick loess covering area,Shanxi is one of the provinces of the national water resources shortage,the rich water aquifer are often included in thick loess areas,which become the main source water supply of local.As a big province of coal mining,a wide range of coal mining is bound to cause many environmental problems in Shanxi province.Seam mining affect the overlying aquifer and even destruction,mainly due to coal mining formed "three zones" named caving zone,fissure zone and band bending,the fissure zone and band bending of "three zones" can influence stability of the overlying loose aquifer.In addition,the existence of fissure zone will also increase water level drop rate of the aquifer,causing leakage of overlying aquifer occurs,mainly manifested as level falling of ground water,spring water cutoff and aquifer unwatering ecological damage problem.Taking Changchun village coal mine as example which based on the areas covered with thick loess,using three groups of similar simulation experiment to study the influence mechanism under the conditions of different mining depth.Experiment show that: the vertical and horizontal displacement the strataincreases with the increase of mining depth,but the regularity is weak,the vertical displacements of observation line in same position of the three models are similar,the existence of key layer will have an impact on the settlement;Horizontal displacement changes of three groups of model are similar,the vertical displacement symmetrical with the center line and have strong regularity;Crack length and area development degree increase with the increase of mining depth,the main key strata will affect the regularity that crack length increases with mining depth,and has no effect on fracture area development regularity;Similarly,residual crack rate decreases with the increase of mining depth,but by the influence of main key stratum,model Ⅱ has the highest rate of residual fracture development degree,the next are model Ⅰ and model Ⅲ;Different mining depth can also affect jump time of the loose aquifer water level decline rate,the smaller the mining depth,more quickly water level decline rate changes,the much bigger influence have on the loose aquifer;In the final analysis it is concluded that mining has influenced the water-resisting function waterproof performance by changing curvature of bottom board which will break the structural stability of loose aquifer.