DEVELOPMENT OF VIBRATION-PROOF METAMATERIALS MODELING OF THE STRESS-STRAIN STATE OF THE UNDERGROUND PIPELINE DURING ROCK SHIFTING IN THE ZONES OF ACTIVE TECTONIC FAULTS

Abstract

Background For a long time in Russia, trunk pipelines have been constructed without taking into account the influence of geodynamic zones on pipeline position. A change in pipeline position in geodynamic zones may occur due to seismic activity, landslides, karst, on the boundaries of tectonic faults. The most common primary movements along faults are shifts, reverse faults and faults, as well as simultaneous joint effects of these movements. The local change in the position of the pipeline that occurs under these effects causes additional stresses from its bending, and the overall stress-strain state worsens, which can lead to the destruction of the pipeline and accidents. Aims and Objectives The objective of this study is to determine the extent to which local ground movements affect the stress-strain state of a pipeline. Methods The stress-strain state of the trunk pipeline in this work is estimated using the ANSYS software package. To do this, the program builds a model of the pipeline in the ground. The local movement of the soil is considered on the example of the shift of rocks in the zone of active tectonic faults. At the first stage of calculation, the shape of the trench for the pipeline does not matter, since the trench is filled with soil that does not differ from the soil outside the trench. The soil shear is simulated, the maximum stresses and the strain of the pipeline metal are determined. At the second stage of the calculation, two different forms of the trench are modeled - rectangular and trapezoidal. The calculation is made for different soil backfill. Results According to the results of the calculation, the dependence of the stresses in the pipeline on the type of soil and the values of the soil maximum displacements that do not cause destructive stresses in the pipeline are determined. It was revealed that filling the trench with more dense soil leads to a decrease in the maximum possible displacement of the soil, and filling it with a less dense soil leads to an increase in the soil shear limit. It was also determined that in trapezoidal trenches the soil can be moved a greater distance than in rectangular trenches. Thus, to improve the stress-strain state of the pipeline in areas of active tectonic faults, it is recommended to use a trench filling with disconnected soil and at the same time to use a filling soil with a lower density and a smaller deformation modulus, and also choose a trapezoidal trench.