Well Trajectory Design And Grouting Effect Evaluation Of Prevention And Control Of Limestone Groundwater In Coal Seam Floor

The No.1 coal seam of Gubei Coal Mine and the Group A coal seam of Paner Coal Mine are located in the Shanxi Formation of the lower Permian system.The limestone of Taiyuan Formation at the bottom is weak in water abundance,and the limestone of Ordovician Formation is weak to strong in water abundance.Under normal circumstances,the hydraulic connection between Taiyuan limestone water and Ordovician limestone water is not close,but in the case of structural communication,Ordovician limestone water will have hydraulic connection with Taiyuan limestone water,become the direct water filling source of the mine,and affect the safety production of coal mine.In this regard,the treatment idea of limestone water disaster in coal seam floor is to carry out grouting transformation of Taiyuan Formation limestone between coal seam and Ordovician limestone,and block the water inrush channel of Ordovician limestone with strong water richness,so as to eliminate the threat of Ordovician karst water disaster to coal seam floor.This paper takes Gubei Nanyi 1 coal mining area and Paner Coal Mine Xisi A group coal mining area as the research object,and uses theoretical analysis combined with engineering practice to study the selection of grouting target horizon,the optimization design of well trajectory and the evaluation of grouting effect in the prevention and control of limestone groundwater damage in coal seam floor.The understanding and results obtained are as follows :1)Reasonable layer can greatly improve the grouting effect.In this paper,the minimum safety thickness calculation formula between the coal seam floor and the lower limestone is deduced by back calculating the critical water inrush coefficient,and the safety mining thickness of the coal seam floor is obtained by combining with the geological model,which simplifies the calculation process.Through the three-dimensional geological model to determine the scope of the grouting layer,analysis of limestone and its roof characteristics,select the optimal grouting layer.According to the occurrence of the selected grouting layer and the main structure,the layout of the branch borehole is determined,and the control points and target coordinates of the branch borehole trajectory are obtained by vertical projection.2)In order to improve the drilling efficiency and create good grouting conditions,this paper establishes the optimal mathematical model with the shortest wellbore trajectory as the goal,and uses the appropriate method to solve the problem.On this basis,a practical calculation program is developed by using VC + + 6.0 and OpenGL,which realizes the calculation and output of the three-dimensional space coordinates of the optimal wellbore trajectory between the opening and the target,and the three-dimensional visualization of the wellbore and the formation,achieving a good human-computer interaction function.3)A fuzzy comprehensive evaluation method based on grey correlation analysis is proposed.Based on specific projects,a multi-index and multi-level comprehensive evaluation system of grouting effect was established.The system uses the analytic hierarchy process to calculate the weight of the evaluation index,uses the grey correlation analysis method to obtain the membership degree of the evaluation index,and uses the fuzzy operation to make a comprehensive evaluation of the grouting effect.In order to improve the computational efficiency,a comprehensive evaluation program for grouting effect is developed on the Visual Studio 2019 platform based on the above theory.The grouting effect of Gubei Nanyi 1 coal mining area and Paner Mine Xisi A group coal mining area is evaluated by using the program.The results are consistent with the actual post-injection effect,indicating that the evaluation model has certain reference significance for similar projects.Figure 40 Table 19 Reference 86...