The Impact Of Geological Disaster On Structure Of Buried Oil And Gas Pipeline

Geological disaster alongthe oil and gas pipeline from Sichuan to East may bring huge troublesintheir structure safetydue todifferent kinds of geological disasters and high frequency of occurrence in south-westof China.Buried oil and gas pipeline structure is desigened priority to with large diameter and thin-walled shell.So it's easily damaged under the disaster occurs,and the production operation would be seriously affected.Based on the geological research analysis along the Sichuan-east gas pipeline,this paper mainly refers to the slope stability and the rock-fall impaction on buried oil and gas pipelines:(1)Taking the compass needle slope as an example,the slope sliding process after the excavation is got by analyzing the stability of excavation with the limit equilibrium slice method,thefast Lagrangian analysis of continua(FLAC)and conituum-based discrete element method(CDEM).It's obvious in the study,it first appeared obvious displacement and dislocation in the upper left and followed the discrete displacement on the upper left of the trench and the right side slope,then the upper left development is obvious local landside,soil slope as a whole has a larger degree of movement to the right after the excavation.(2)The dynamic response of buried pipeline under the rock-fall impaction is analyzed with the landside rock-fall impact model established by using three-dimensional discrete element program 3DEC,in which pipe using the linear unit and backfill soil using Moore coulomb plastic model.It's obvious that:Under the impact of small falling body weight,the ground vibration frequency distribution is uniform,and under the heavy weight,ground vibration containsmore low frequency components.The impact load mainly cause the earth pressure change on the upper part of the pipeline,as the impact area increases,the scope increases;as the impact area and height of falling body is equal,increasing the falling body weight will result that the largest soil pressure at the top of the pipe significantly increases and the impact on the earth pressure at the lower half is not significant.The impact area along the vertical earth pressure on the surface of a pipeline is roughly twice of the impact radius.(3)Based on the finite element software ABAQUS,a multi landslide rock-fall impact model is established,and the influence of shape,size,and order on the stability of the pipeline.The result show that:As the same volume,ellipsoid rock-fall produces greater deformation than sphere rock-fall;as the same shape,the larger rock-fall volume is,the greater the pipeline deformation is.Pipeline dangerous pressure area is only 1/6 of the pipe,indicating a partial destruction of rock-fall impact damage.Impact order has smaller influence on pipeline deformation.(4)The effect of engineering parameters on the stability of the pipeline is analyzed,it found that rock-fall impact velocity is a major factor affecting the safety of buried pipeline,the faster the speed,the greater the pipe deformation;in the same conditions,the increase of buried depth will protect pipelines better,but it will significantly increase the cost of construction;compared with the hardclay used as fill material,sand is more likely to cause the pipeline deformation.(5)A dynamic monitoring and GIS information system platform of geological disasters,including GPS geodetic deformation resources and satellite remote sensing data of RS,has been proposed.The implementation of this project has important strategic significance to the national pipeline network construction.