Study On Risk Assessment Of Shallow Buried Gas Pipeline In Gob Area Of Steeply Inclined Coal Seam

Due to the wide distribution of coal mines in my country,natural gas pipeline projects will inevitably pass through goafs in coal mines.Therefore,the risk assessment research on gas pipelines passing through goafs,especially steeply inclined coal seam goafs,is of great importance to the safety of gas pipelines.Operations are important.In this thesis,relying on the Qianjiang-Shaoguan Gas Transmission Pipeline Project Chashan mine section gas transmission pipeline project（the gobs in the area are all steeply inclined coal seam goafs）,using the 15th coal goaf in the research area as a geological prototype to explore The impact of different mining depths and mining thicknesses on shallow-buried gas pipelines in goafs in steeply inclined coal seams is obtained through similar simulation experiments:the deeper the mining depth is in the goafs of steeply inclined coal seams,the smaller the deformation of shallow-buried gas pipelines;In the goaf of steeply inclined coal seam with greater mining thickness,the alignment change of shallow buried gas pipeline is greater.This guides the selection of goaf factors in the risk assessment model,and the determination of the mining depth and mining thickness factors.Based on the comprehensive geological overview of the study area,review of relevant literature and specifications,and the results of similar simulation experiments,a two-level fuzzy comprehensive evaluation model of the risk of shallow buried gas transmission pipeline in the sharply inclined coal mining area of the Chashan mine section was constructed with natural environmental factors,engineering geological factors,mining area factors,and pipeline factors as the first-level factors,and the weights of each factor were determined using the hierarchical analysis（AHP）.In order to verify the practicability and accuracy of the established fuzzy comprehensive evaluation model,the risk assessment of the shallow buried gas pipeline passing through the steeply inclined goaf of No.The safety level is Class I（safety）.At the same time,using the Abaqus2022 finite element analysis software,the modeling and analysis of the shallow buried gas pipeline in the steeply inclined gob area of No.21 coal mine is obtained,and the maximum axial additional stress on the pipeline is24.66 MPa,and the calculated von Mises combined stress of the pipelineσ_Mises=193.14MPa.Far less than the minimum yield strength required by the code.Therefore,it can be verified that the shallow-buried gas transmission pipeline in the goaf of the 21 coal steeply inclined coal seam in the Chashan mining area is in a safe state,and then the accuracy of the fuzzy comprehensive evaluation model is verified.The thesis has 39 figures,37 tables,and 86 references.