Research On The Technology And Application Of Quickly Constructing Permanent Sealing Wall For Connecting Lane With Paste Filling

If the permanent sealed wall of the underground connecting roadway in a coal mine is damaged due to compression,resulting in air leakage,it will increase the risk of fire in the goaf,thereby bringing a huge impact on the safe and efficient mining of the coal mine underground.At present,the permanent closed wall in coal mines in the northwest region of China adopts the form of inner concrete wall,loess,brick wall,and outer concrete wall.This construction method requires a large amount of materials,requires a large amount of construction manpower,and takes a long time,resulting in a high labor intensity and high cost for workers.Whether considering economic or social benefits,this traditional permanent closed wall construction method is not suitable for the principle of modern mine safety,efficiency,and high yield.In order to solve the problems of high cost of paste materials and complex construction process in the construction of permanent sealed walls for connecting tunnels mentioned above,a systematic study was conducted on the construction of a permanent sealed wall in a certain mining area,using a combination of laboratory experimental analysis,theoretical analysis,and numerical simulation to study the paste filling materials for the sealed wall,relevant parameters for the construction of the sealed wall,and the sealing filling process,Provide theoretical basis and technical support for the rapid construction of permanent sealed walls through paste filling.(1)According to the flowability test,rapid setting test,and compressive strength test plans of the paste filling material based on coal gangue,the slurry flowability,rapid setting property,and compressive strength of the coal gangue paste filling material specimens were tested and analyzed.Taking into account the low preparation cost,the various parameters of the coal gangue paste material at the optimal ratio were determined as cement: fly ash: coal gangue=1:3:6,and the mass concentration was 80%,The addition amount of J85 accelerator is 6% of the cement content,and the effect of improving the initial setting time of the paste slurry with this addition amount can reach 35.4%.Under this optimal ratio,the slump of the paste is 226 mm,the initial setting time is79 minutes,and the compressive strength at 28 days is 7.69 MPa.(2)By analyzing the sealing mechanism,sealing reliability indicators,and the theory of air leakage hazards of the sealing wall,the feasibility of quickly constructing a permanent sealing wall with paste filling under the optimal ratio in this article was verified.Through theoretical analysis,it was found that the peak area of lateral support pressure in the connecting roadway is 8.63-10.32 m.As the optimal construction position of the permanent sealing wall should be arranged in the stress reduction area,and at least 6m should be left for the blind alley in the connecting roadway,The optimal construction location for the permanent sealed wall should be within a range of 6-8 meters near the channel side.At the same time,it is concluded that the minimum reasonable width for the construction of permanent enclosed walls is 1.89 m.(3)Taking the construction of a permanent sealing wall in a certain mine as the research object,a numerical model was established based on the actual situation underground and relevant mechanical knowledge.Numerical simulation was conducted using FLAC3 D software to analyze the distribution and variation of stress and displacement fields under different strengths and widths of the permanent sealing wall.The optimal construction location for the permanent sealing wall in the goaf was found to be 6 meters away from the intersection of the channel and 6 meters away from the goaf,Based on the principle of saving materials as much as possible and reducing costs while meeting a certain pressure capacity,the reasonable construction width of the permanent sealing wall is determined to be 2m,and the compressive strength of the filling body of the permanent sealing wall is determined to be 8MPa.(4)In response to the on-site situation underground,a mobile pumping system for surface slurry production has been proposed,and specific optimization designs have been made for the layout of underground filling pipelines and the permanent sealed wall filling bags.According to the on-site monitoring of the gas concentration in the connecting roadway,the stress and deformation of the permanent sealed wall,it can be seen that when the connecting roadway is filled and sealed with a permanent sealed wall,the gas content in the connecting roadway outside the permanent sealed wall decreases to below 0.4%,effectively preventing the leakage of gas from the goaf into the outside world,And the stress and displacement deformation of the permanently sealed wall remain basically unchanged at 70 m behind the working face and 80 m behind the working face,respectively.Overall,the monitoring analysis shows that the rapid construction of permanent sealed walls using paste can effectively block the connecting roadway.