Experiment And Application Research On Grouting And Filling Materials In The Goaf Area Under The Pipeline Line

To ensure the safe operation of the gas pipelines in a coal mine in the northern of Shaanxi province,researches were carried out through theoretical analysis,numerical simulation,laboratory test,field measurement and engineering application.Firstly,movement and deformation of gas pipelines have been analyzized due to the mining influence of woking face.And mechanical strength and flow performance of grouting filling material also have been studied.The specific research results are as follows:(1)The influence scope and degree of the gas pipeline were determined by the probability integral method due to.The influenced length of gas pipelines was273.66m,and the maximum movement deformations(maximum subsidence as197mm,horizontal deformation as 4.8mm/m,tilt as 5.3 mm/m)of gas pipelines also were confirmed.And the damage level of the gas pipelines wasⅡdegree.(2)The ground grouting and cemented filling technology in caving zone was proposed by comparing the control measures.And mechanical strength of filler baby was determined as not less than 2.5MPa through numerical simulation.Through studying mechanical strength properties of grouting filling material,and analysizing the observation of SEM,optimal match range(mass concentration as 75%～78%,cement content as 5%～10%,fly ash content as 10%～25%,gangue content as40%～50%,3～5mm gangue ratio as 30%～40%)were sured.(3)Through studying slurry flow performance,optimal match range of superplasticizer was 3%～5%cement weight.At the same time,the flow performance of 75%、78%、80%mass concentration slurry were doubled.And the outdoor simulated slurry filling gangue test verified the good flow performance of the slurry between the gangue gaps,and mechanical strength of filler baby was 2.6MPa.(4)47 curtains,32 grout holes were arranged and 43955m~3 slurry were grouted.And GNSS monitoring data showed that the cumulative value of subsidence in 6months is less than 30mm,which verified filling was feasible and effective.The conclusions of this research provided reference for backfill mining under pipelines and study of grouting material with gangue and fly ash.