INFLUENCE MECHANISM OF PIPE TRENCHES ON THE MECHANICAL PROPERTIES OF NATURAL GAS PIPELINES IN THE GOAF SUBSIDENCE AREA

摘要

In order to improve the accuracy of pipeline stress prediction in the goaf subsidence area, the in-fluence of pipe trench parameters must be consid-ered. However, the problem is rarely considered in the stress analysis of buried pipelines in the goafcol-lapse area. In this paper, a buried pipeline model in the goaf with pipe trench parameters is established by using the ABAQUS finite element software. The stress changes of pipeline with and without pipe trench is compared, and the effects of physical pa-rameters such as pipe trench slope, widening allow-ance, and backfill on the Von Mises stress of the pipeline are also analyzed. The results show that the pipe trench can effectively reduce the pipe-soil force in the goaf. The greater the width of the goaf, the more obvious the reduction of pipe trench on pipe-line stress. When the width of the maximum goaf is 300m, the Von Mises stress on the outer wall of the pipe top is reduced from 449.27MPa to 325.63MPa. which is reduced by 27.52 %.With the increase of the pipe trench slope gradient, the pipeline stress gradually increases, but when the slope gradient of pipe trench A≥ 1.0, the change of maximum Von Mises stress on the outer wall of the pipe top does not exceed 2%.With the increase of the width of the trench bottom, the pipeline stress gradually de-creases, but when the width of the pipe trench is greater than 2m, the maximum Von Mises stress on the outer wall of the pipe top hardly changes. The density and elastic modulus of backfill have a linear positive correlation with the maximum Von Mises stress of pipeline.