The Research On The Law's Prediction Of Water Inflow And Prevention Technology In Thach Khe Open-cast Iron Mine,viet Nam

Research Open-cast Mining is controlled by complicated Hydrogeological conditions water disasters and its scheme for water optimization,this study is an important effect on ensure the mine production for safety.This study through Viet Nam Thach Khe open-cast iron mine of hydrogeology survey,as well as Open-cast mine area of the calendar year maximum daily rainfall and the average annual rainfall data for comprehensive analysis,building a numerical model of groundwater flow of the mining area,based for some heavy rain to design of frequency,respectively to calculated the water inflow of the mine in different mining periods of the mine.This data as the basis for study open-cast waterproof and drainage system,proposed in scheme for waterproof and drainage.This study of main knowledge and the conclusion as follows:1)Through the detailed study and prospect for hydrogeology conditions in the mining area,analysis of the characteristics of underground aquifer of the mine area,and hydraulic relationship between each other aquifer stratum.The results show that the mining area is divided groundwater into four aquifer stratum and two aquiclude stratum.Respectively,water-bearing stratum of the Quaternary period,aquiclude stratum,Waterbearing stratum of the Neogeneous period,aquiclude stratum,Upper water-bearing stratum of the strong rock layer and Lower water-bearing stratum of the strong rock layer.And further,determine the hydrogeological parameters of aquifer,and determine the chemical composition of surface water and groundwater.2)Using finite difference method of GMS software's Modflow module,building a mathematical model(3D)of groundwater flowing into the minning area,forecast the groundwater inflow into the mines at 8 stages of mining,from 2800 m~3/h(year 4)to 14250 m~3/h(year 37)before closure when an ingress volume of 14450 m~3/h is expected.the comparison of the modeling result with the practical observation result shows that the forecast modeling result is 4.1% higher than the practical observation result,to ensure model data reliability.3)Analysis the open-cast mine of selection principles of drainage system and opencast mine of the common drainage methods of virtues,defects;determined method of two levels of open pit mining system and scheme for mines excavating.After that,according to the simulation results of forecast the groundwater inflow into the mines.Put forward the Thach Khe opencast iron mine drainage system and form a complete set of mining plan,Include the two systems: the prevention and control of water from the mines outside of protection system and the mines internal drainage system.4)By the use of GMS software well modul to calculate the groundwater pumping well of arrangement scheme,mainly includes: the sedimentation shell of water aquifer stratum of pumping well system and the water-bearing stratum of the strong rock layer of pumping well system.Finally calculated the mining area at 8 stages of mining of pumping well amount: 50 pumping well(year 4),64 pumping well(year 9),80 pumping well(year 13),83 pumping well(year 16);from year 24 to end of mining,pumping well system arrangement on the border of mine and each of stage using 93 pumping well.Pumping well system can ensure the pump capacity is 11×10~3 m~3/h,ensure drain off 75% groundwater flow into the mines.5)According to statistical data of the recent 23 years rainfall,Using the Gumbel extreme value distribution theory method,Analysis the mining area of rainfall intensity frequency,calculation the quantity water inflow into the mines internal,including rainfall and the remaining 25% of groundwate,put forward the mines water collection hole specifications.Determined scheme the arrange equipment and the drainage direction.Ensure that in the event of a five years a maximum rainfall link in the drain off the water requirements.6)By the use of GMS software MT3 D modul,building Thach Khe iron mines area of groundwater solute transport model,forecasted the concentration of brine and scope and range of influence at each period of mines.In the sediments stratum of concentration by brine change in the water is 1.5 ~ 35 g/L,affect the range of 0.4 ~ 7.7 km.In the waterbearing stratum of the strong rock layer,the concentration by brine is greater than 5 g/L,affect the range of 0.45 ~ 1.8 km.Finaly,put forward demand selection of pump water equipment.