Dynamic Behavior of Underground Viscoelastic Pipelines Under Seismic Impact in the Form of Real Earthquake Records
Gazi Turkiya
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| Keywords
Viscoelastic Soil Stress-strain state Polymer pipeline Underground structures |
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INTRODUCTION
In seismically active areas, the design and construction of underground structures should take into account the actual movement of soil in the event of possible earthquakes. The leading importance in solving this problem is the development and improvement of methods for calculating underground structures that take into account the real interaction of structures and soil under dynamic influences. The actual data on the behavior of underground structures during strong earthquakes show that the stress-strain state is influenced by the physical and mechanical properties of the soil and structures, the nature of the seismic impact, design features, geometric dimensions and depth of the underground structure [1-5]. Considering the above, the study of the strength properties of underground pipelines, in particular of polymer materials, in structurally heterogeneous and moistened ground conditions of their operation, taking into account the consequences of possible seismic impact, is an important practical problem. The study of the seismic resistance of underground structures, taking into account all these factors in the complex, determines the use of numerical calculation methods focused on the use of computing tools.
The use of new composite materials in engineering practice, as well as the design and creation of durable, lightweight and reliable structures requires the improvement of mechanical models of deformable bodies and the development of more advanced mathematical models, their calculation taking into account the real properties of materials and their geometry. Therefore, the development of effective algorithms that are used to solve the problems of underground polymer pipelines is an urgent task [6-8].
To date, there are theoretical and experimental studies in domestic and foreign science to determine the stress-strain state (SSS) [1-20] of underground pipelines interacting with the surrounding soil under seismic influences. In [3], a theory of the process of propagation of seismic waves in an underground pipeline and the surrounding soil, called the wave theory of seismic resistance of underground pipelines, is proposed. This theory is used to analyze the longitudinal vibrations of the pipeline during its interaction with homogeneous soil according to linear and nonlinear laws, and problems are solved taking into account the wave propagation process in the soil and pipeline using the characteristics method.
In the article [6], longitudinal vibrations of underground polymer pipelines under seismic loads are studied. An algorithm and a program for calculating seismic resistance have been developed, while the viscoelastic properties of the pipeline material are taken into account by applying the Voigt model.
The purpose of this work is to study the SSS of an underground polymer (viscoelastic) pipeline under seismic impacts in the form of real earthquake records. A mathematical model of the dynamic behavior of a viscoelastic pipeline under an arbitrary direction of seismic loading has been developed. The problem is solved by the finite difference method. Changes in displacement, stress, shearing forces and bending moments over time and along the length of the pipeline are obtained. The viscoelastic properties of the pipeline material are described through a three-parameter Rzhanitsyn – Koltunov core, the method described in [21] is used for conversion.
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