Research On Quality Evaluation Method Of Water Prevention And Control In Mine Curtain Grouting

With the rapid growth of national economy,the exploitation of mineral resources is developing to the deep and more and more difficulties are encountered.Curtain grouting technology for water plugging is widely used.It is applied in the safe mining of most water-rich karst deposits in China.However,the curtain grouting project is a typical concealed project,and its grouting effect evaluation has not yet met the uniform standard.Based on the curtain grouting project in Linihu,the quality of grouting project in the mining area is evaluated separately by means of data analysis,inspection hole,CT detection,pumping test and groundwater simulation,with the lack of quantitative evaluation criteria for single-factor evaluation or multi-factor mixed evaluation of curtain grouting engineering.Combined with fuzzy comprehensive evaluation,a comprehensive evaluation system is established to evaluate the curtain quality systematically.The contents and results of the paper are as follows:(1)Research on preliminary evaluation of curtain grouting quality.On the basis of curtain survey,design,construction data and related records in mining area,data analysis method,inspection hole method and CT tomography technology are used to check and analyse the changes of permeability and suction of boreholes in each sequence,pore pressure water test,strength test of magmatic rock stones,curtain karst crack status and construction process records.The results show that:1)With the increase of drilling sequence,the average permeability of boreholes decreases from 4.820 lu in sequence I to1.170 lu in sequence III,and the unit grouting volume decreases from 11.940 m~3/m to2.937 m~3/m.2)The average permeability of the inspection hole is 0.316 lu,which is 90%less than that of the adjacent borehole.3)The compressive strength of slurry rock is distributed between 20-60MPa,which indicates the strength of the stone body is high.4)The original karst cave or rock fractured section is well sealed,and there is no large seepage passage.All the indexes meet the design requirements and relevant engineering quality standards.It is preliminarily judged that the curtain grouting engineering in the Linihu mining area is of excellent quality.(2)Research on the the numerical simulation of groundwater.Based on the analysis of hydrogeological conditions of the mining area,it is generalized.The scope and boundary conditions of the model,the structural properties of the aquifer,and the source and sink terms of the system are determined.Using Visual Modflow three-dimensional groundwater numerical simulation software,a isotropic unsteady flow numerical model is constructed.The numerical model is corrected by fitting the water level of the observation hole.The corrected model is used to analyse the horizontal sections of-125m,-165m,-205m after curtain grouting to predict the water inflow and the variation of groundwater flow field in different sections.(3)Research on the steady flow pumping test.According to the current production and pumping capacity of the mine,a steady flow pumping test for three deep drawdown of-60m,-130m and-200m is carried out using existing main wells.The equivalent permeability coefficient of grouted composite rock mass is calculated by using the formula of combining the single well pumping and multi-observation holes.The"Dajing Method"is used to predict the water inflow in the horizontal section of-125m,-165m and-205m.The calculation results show that the water inflow after the curtain is significantly reduced.The horizontal water plugging rate at-165m is 71.46%,and that of-205m is 77.44%,which meets the requirement of curtain design.(4)Research on fuzzy comprehensive evaluation of curtain grouting quality.The main factors that affecting grouting effect are analyzed and determined.By means of tomographic analysis,a grouting effect evaluation index system is established,which includes curtain designing,grouting material,drilling water pressure test,grouting capacity,inspection pore water pressure test,grout stone quality,fracture filling,pumping time history curve,observation hole depth decline time history curve,the prediction of water inflow and the groundwater flow field.Three criteria for evaluating the effectiveness of grouting are classified as excellent,qualified and unqualified after the evaluation factors are quantified.The evaluation system is used to evaluate the quality effect of the curtain grouting project in the Linihu mining area.It shows that the curtain water blocking rate matches the designing requirements.And the quality of the curtain meets the grade of excellent,which is exactly consistent with the actual situation.