Stress Analysis Of Gas Pipeline In Inclined Shaft

The main methods of pipeline crossing are directional drilling, tunneling and pipe driving; the tunnel inclined shaft through the form appears. Tunnel crossing laying compared with the excavation of homeopathy, tunnel crossing overcomes the elevation and terrain obstacles, decreases the difficulty of pipeline construction, even reduces damage to the vegetation and soil erosion, it can reduce the project cost, the maintenance cost of the pipeline. Hence the increasing maturity of the pipeline tunnel crossing is becoming one of the special section of pipeline construction and reliable method. For example, defender of the Yellow River tunnel crossing the distance of 1198 m in 2011 and the square bucket mountain tunnel length of 3083.2 m in 2010.For the crossing tube, topographical constraints and maintenance inconvenience lead to more serious consequences, an important reason is the elbow segment does not meet the strength requirements arising from the failure of destruction. Pipeline design is the basis quality for construction; pipeline design rationality is directly related to the structural safety of the pipeline. At present crossing tunnel structure depend only on empirical parameters, so the pipe stress analysis should be taken seriously into consideration for the piping design.The study of the tunnel involved the inclined structure. When analyze the pipe stress in various operating conditions, in addition to the impact of pigging, the weight, pressure, temperature and external forces caused by the static load are only considered, Wind load and dynamic load is not carried out.Main research contents of this paper are:(1) Theory of stress analysis for gas pipelines within the inclined pit structure, then proposed reasonable incline gas pipeline force model.(2) Analysis of the inclined gas pipeline loading:static load (including gravity, internal pressure, temperature stress, water buoyancy), dynamic load (pigging impact load.(3) Analysis of the mechanical characteristics of the inclined gas pipelines in different operating conditions. With CAESAR Ⅱ software, we established the stress models for installation conditions, pressure testing condition, pigging condition and operating condition.(4) According to the motion law of scraper and transient analysis during pigging, the pigging transient motion model is established to analyze the load of scraper through the inclined gas pipeline.(5) By numerical simulation analysis of pipe stress and strength check of critical stress concentration points, we research the relationship of inclined gas pipeline design parameters and the tunnel structure parameters, then find out the relationship between the inclined structure parameters (design angle, well length) and pipeline parameters.Because less research has been done at home and abroad for the inclined pipe stress analysis, this study proposed theoretical stress analysis, universal force model and parameters’ relationships of the gas pipeline under inclined structure, it provides a theoretical basis of pipeline stress analysis in tunnel and safety parameters range for design. CAESAR II software models also provide a gas pipeline model template in the inclined for designer. The research results fill the blank of domestic and foreign special deposition tube under the gas pipeline stress analysis method to some extent, provide basis that the refinement design can be followed, and place the strength safety and structural safety in the same position.