Numerical Simulation Of "Fourth Aquifer" And Subsidence Induced By Drawdown Of Water Table In Banji Coal Mine

In this paper,the’fourth aquifer’of Banji coal mine is taken as the research object.By consulting the relevant literature and using the water level monitoring data of different aquifers,the hydrogeological conditions are analyzed,and the coupling model of groundwater numerical model and land subsidence is established.The MODFLOW and SUB modules in GMS are used to analyze the relationship between water level drawdown,settlement and settlement threshold time.The main research contents and results are as follows:(1)The dynamic characteristics of groundwater level in’first aquifer’,’second aquifer’,’third aquifer’and’fourth aquifer’in recent years are systematically analyzed and summarized,and the causes are analyzed.The first and second aquifer are affected by atmospheric precipitation,surface recharge,surface evaporation,etc.’third aquifer’affected by surface domestic water mining;the water level of’fourth aquifer’and nine-coal seam’sandstone’is affected by the current underground drainage.(2)The thickness fluctuation model of bedrock surface and’fourth aquifer’is constructed.The thickness of’fourth aquifer’gradually increases from southeast to northwest,but the thickness variation of some sections is quite different.(3)The hydrogeological conceptual model and unsteady flow mathematical model of’fourth aquifer’are established.The corresponding simulation model is established by GMS,and the hydrogeological parameters of aquifer are identified and verified.(4)The coupling model of groundwater flow and land subsidence based on SUB module is established to simulate the influence of indirect release water of’fourth aquifer’on land subsidence near the industrial square.It is determined that when the water level drop is 15 m,the corresponding settlement prediction drop is 10 mm.(5)The mathematical statistics method is used to establish the relationship model between the amount of water discharged from the underground aquifer and the water level duration curve,and to predict the corresponding discharge time under different water level drawdown conditions of’fourth aquifer’.When the release amount of’fourth aquifer’is 20m~3/h,it takes 258.63 days for the water level of Guan 1 to drop12m(the threshold water level of land subsidence)and 323.04 days for the water level to drop 15m(the threshold water level of land subsidence).Figure[51]Table[14]Reference[95]...