Numerical Analysis And Evaluation Of Impermeability Of Large Grouting Curtain

The mineral resources of the Huang Tun matte iron mine is extremely rich and has high economic benefit of exploitation in Anhui province.However,it is difficult to exploit because the mine occurrs in the plentiful water aquifer where inflow of water is large.For the safety of mining mineral,large grouting curtain was used to prevent lateral inflow,but complicated geological conditions in the study area resulted in poor impermeability of water-proof diaphragm.Thus,it is significantly important to adopt the reasonable method to evaluate the hydraulic barrier effect and predict water inflow for safe working in the later period.In this study,strong rich watery surrounding rock and large impermeable barrier in Huang Tun matte iron mine were selected as research object.On the basis of analysis of hydrogeological and geological exploration data of study area,the spatial distribution characteristics of aquifer and aquiclude,the mechanism of the circulation of groundwater and the law of rich water were analyzed,and the mainly water-filled factors of deposits was summarized.Combining with the two large-scale group hole pumping test,the three-dimensional groundwater flow model of the study area was established by Feflow software.The water flow field and the quantity of water inflow of the study area were predicted and the effectiveness of impervious wall was valued.The geological structure of the study area is complex,and the development of fault and fracture zone constitutes the leading water channel.The aquifer,being rich in water and the large lateral recharge,is not easy to dry out.Aquifer water abundance and law of water conducted of geological structure were analyzed,and hydrogeological parameters in the natural flow were obtained by the two large group drilling pumping test of hydrological observation data before and after the building of the curtain.The impermeability of grouting curtain was judged qualitatively according to the change of flow filed,which provides guidance for the parameters partition of 3D hydrology and geological model.Based on the analysis and generalization of the geological and hydrogeological conditions,a conceptual model and 3D geological model of hydrogeology in the study area was established by using the groundwater numerical simulation software.According to the pumping test of the hydrogeological exploration,the results of natural flow field were simulated by the finite element software Feflow.After parameters zooning,source sink term treating and model identifying,experimental verification and error statistics of model were carried out.The result showed that the model with the high fitting degree,reasonable structure of aquifer and accurate boundary conditions can reflect the hydrological condition and provides the basis parameter for the numerical simulation of flow field already confined by the wall.According to the pumping test data inspecting curtain,parameters of curtain were inversed.Mining water inflow dynamic prediction and the impermeability of grouting curtain of-240 and-340 level were obtained by the calibrated model.The results showed that water blocking rate of grouting curtain is about 65%,where the west curtain reaching 70% is the best;Due to the gap,the south curtain grouting being the most poor,was only 60%.