Safety assessment of buried pressurized gas pipelines subject to blasting vibrations induced by metro foundation pit excavation

Abstract

Ensuring the safety of adjacent pressure gas pipelines is a key issue in the blasting excavation of foundation pits in complex urban environments. In this paper, the blasting excavation of the foundation pit of the second stage of Wuhan Metro Line 8 was selected as a case study, and the blast vibrations in the field were monitored. Based on the data obtained, a mathematical model was proposed to describe the attenuation of the peak particle velocity (PPV) of ground surface soils with respect to the depth of the foundation pit excavation. Next, a 3D numerical calculation model was established to analyze the response characteristics of a buried gas pipeline, with a 0.4 MPa internal operating pressure, subjected to blasting vibrations. The reliability of the model was verified using the field monitoring data. Then, the dynamic response characteristics of buried gas pipelines with different internal operating pressures were discussed, and the functional relationship between the PPVs of the pipeline and of the ground surface soil above the pipeline was summarized. Combined with the PPV attenuation model of the ground surface soil, the mathematical expression describing the PPV of the gas pipeline was proposed. Lastly, a prediction model of the peak von-Mises stress of the pipeline, with different operation pressures, subject to blast vibrations was established, which can be used to assess the safety of the pipeline under the influence of nearby foundation pit blasting construction.