Study On Settlement Mechanism And Vibration Characteristics Of Buried Gas Pipeline Over The Mined-out Areas

Aiming at the buried gas pipeline system over the mined-out areas, its settlement mechanism and lateral vibration characteristics on the uneven settlement of foundation were studied. The main research contents include: 1.The buried gas pipeline settlement deformation over the mined-out areas was analyzed and its stiffness was checked; 2. Analysis on the stress and the permissible settlement of buried gas pipeline was analyzed; 3. The buried gas pipeline transverse vibration under fluid-solid coupling was analyzed.The mechanics model and deformation differential equation of the gas pipeline over the mined-out areas with multi differential settlement was established, and the analytical expression of pipeline deflection was derived.The pipeline deformation was studied by using the expression, and that was compared with the measurement results. On this basis, the angle and the curvature of the pipeline were studied, and the current security state of the pipeline was checked by the research results. At the same time, this buried gas pipeline stress was studied by this expression, and the pipeline permissible settlement was determined. The research shows :(1)The established mechanics model and the derived analytical expression are applied to study the gas pipeline deformation and stress with multi differential settlement.(2)The permissible settlement of the pipeline can be determined according to the horizontal distance between the two adjacent extreme points.This gas pipeline was simplified as a simple supported beam. Taking account to the influence of temperature, the transverse vibration differential equation under fluid-solid coupling was established by using of the Hamilton generalized principle. The influence of temperature, velocity, fluid pressure,pipeline length, pipeline wall thickness and pipeline diameter on the natural frequency and displacement response of this gas pipeline was studied by the Galerkin method. The results shows:(1)Within the velocity limit of technical specifications, the influence of the natural gas velocity is very small on the dynamic properties of the gas pipeline, and this influence can be neglected.(2)The gas pipeline length is the most main influence factor on its naturalfrequency, and the second is the natural gas pressure.(3)Temperature variation and pipeline length are the main influence factors on the displacement response of the gas pipeline.