Research on Anti Collapse Technology of Drainage Hole for Accumulated Water in Weak Interlayer Rock Layer Empty Area
Aiming at the problem that the boreholes are prone to collapse,shrinkage,and blockage of drainage channels during the process of releasing the overlying goaf accumulated water of the working face due to the influence of weak overlying rocks between coal seams,resulting in low efficiency and even inability to release accumulated water in the goaf,taking the 13103 working face of Ciyaogou Coal Mine as the research object,a water drainage drilling hole anti collapse hole protection pipe is developed based on the strength theory of the screen pipe.The application of the protection pipe in the accumulated water drainage engineering in the goaf of weak interlayer rock layers is conducted to be studied.The results indicate that the poor integrity of weak sandstone between coal seams and the instability and fragmentation of the roof rock strata in goaf are the fundamental reasons for the occurrence of borehole collapse and reducing diameter;The protection pipe adopts a steel made pipe body and threaded connection.The pipe wall is equipped with water drainage holes and inverted ropes.Through the strength checking and verification of the screen hole protection pipe and the optimization and selection of the screen hole parameters,the diameter of the water drainage hole is determined to be 16 mm,the density is 28 holes/meter,and the phase angle is 30°;The problem of hole collapse can be effectively solved by installing steel made screen pipes in the soft rock hole section.After the application of protection pipes,the attenuation of drilling water output is significantly reduced,and the maximum drainage rate of a single hole is increased by 58.3%.
weak interlayer rock layerdrainage of accumulated water in empty areaanti collapse hole protection pipestrength checking and verificationoptimization of screen hole parameters
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