Study On The Mechanical Analysis Model Of Pipelines In Soft Ground Under Traffic Loads

As an effective method, pipelines play an important role in modern industrial, agricalture and people's life. It is called the fifth transport way except the highway, railway, water carriage and airway. So pipelines were called the lifeline engineering, too. With the development of the society and the level of the citizing, the destroyed actualities of the pipelines were affecting the normal life and manufacture of the people. So people put more attention to this problem and bring forward higher demands for the dependability and the security of the pipelines in the soft soil under the traffic loads. To carry out the research of the chanmical charachers of the pipelines in the soft soil under traffic loads is needed for the development of the society, construction and life.After analysising the correspondence literature of the pipelines home and abroad carefully, the hotspot and the difficulty on the pipelines' chanmical properties were brought out.Based on some suppositions, this paper established the model on the foundation beam of the pipelines under the long-term and symmetrical traffic loads. So the chanmical properties and the effect of the timbering form, foundation modulus and stiffen coefficient of the pipelines under static loads were studied, which provided the research basic for the chanmical properties of the pipelines under dynamical loads.The mutual effect of the pipelines and the soil under the dynamical loads is belonging to a coupling system. The essential properties like randomicity; dynamic; coupling; nonlinear and so on of the system of pipelines-soil under dynamical loads was studied through loads, soil, and pipelines-soil etc three aspects, so this chapter offers the basic job for the dynamical response of the pipelines-soil system.Eular -Bernonulli beam model and Tomosimko beam model were adapted to study the inherence vibration properties of the pipelines under dynamical loads, and the analytical answers of the chanmical results were brought out in the fifth chapter. And gave priority to the Eular -Bernonulli beam model, the simply and convenient analytical resolution for the response of the pipelines under dynamical traffic loads through the impulse function and the congruence method of the vibration form and so on. During the analysis of the chanmical results of the pipelines, the randomicity of the output of the pipelines response was taken into accout. So the stochastic process method was applied to describe the probability characters of the pipelines response, which made the results truer, more veracious. At the same time, the character of dynamical parameterunder dynamical loads was taken into accout, so elastic Eular -Bernonulli foundation beam model under traffic loads was set up. In this model, firstly, the detailed resolution process accounting the parameters changing with the space was gained; secondly, the detailed resolution process accounting the parameters changing with the time was gained, too. So the integrality of the analytical resolution was preserved in term of the single parameter and the multi-parameters when the pipelines-soil system's parameters change with the space and time under dynamical loads.Continuous multi-segment beam model is the other method of the common used model on the study of the pipelines. During the sixth chapter, such simplified model was adapted for the pipelines under dynamical traffic loads. So the framework chanmical way was adapted to study the character of the pipelines'response under trigonometric function traffic loads; then the randomicity of the parameters were taken into account, the paper uses the perturbation theory to describe the random character about the changing parameters of the pipelines. The calculate formula and simply resolution of response character of pipelines under random loads was educed.The technique of numerical value can stimulate the complex actual situation effectively. So FEM was applied to calculate the longitudinal and the transverse chanmical chatacter of the pipelines under the unalt...