Landslide is the main factor threatening the operation safety of long-distance gas pipeline, and the internal corrosion of pipeline will also seriously affect its reliability. Using LS-DYNA software, considering the interaction between pipeline and soil, a model of pipeline with defects crossing landslide is established based on the coupling of smoothed particle hydrodynamics and finite element method (SPH-FEM). The effect of the depth, number and spacing of pipeline defects and gas pressure on the mechanical behavior of pipeline is analyzed. The results show that the corrosion defects and gas pressure have little effect on the deformation of the pipeline. It is also found that when the gas pressure of the pipeline increases gradually from zero, the residual strength of the pipeline has a maximum value. Additionally, for the single corrosion defect, the maximum plastic deformation appears in the center of the corrosion defect, but for the double corrosion defect, it appears in junction of the corrosion defects. Furthermore, with the increase of landslide displacement, the plastic strain zone gradually extends along the circumference of the pipeline in these two kinds of defective pipelines. At the same time, the interaction between adjacent corrosion defects is found. The interaction is related to the defect spacing: within a certain range, the interaction increases with the increase of the defect spacing, the maximum equivalent stress appears at the junction of defects, and the stress concentration area expands along the circumferential direction. With the further increase of the spacing, the interaction disappears.
To determine and
optimize the emergency evacuation path of personnel
in the case of vapor cloud explosion caused by pipeline leakage and
improve the safety control measures in the high-consequence areas
of gas pipelines, this study was conducted. This work mainly studied
two questions: whether various research methods applicable to the
solid explosive explosion are also applicable to vapor cloud explosion
and the influence of different building layouts on the overpressure
propagation law of vapor cloud explosion. First, the applicability
of several empirical models and computational fluid dynamics (CFD)
methods in vapor cloud explosion overpressure prediction is systematically
compared and analyzed. Second, the finite element models based on
the fluid–structure interaction are established to study the
overpressure propagation law under the influence of different building
layouts. Finally, based on the overpressure propagation law, the determination
and optimization principle of the emergency evacuation path of personnel
when an accident occurs are given. The results show that the CFD method
and empirical model based on equivalent assumption between trinitrotoluene
and combustible gas are not suitable for the study of gas-phase explosion,
while the mixed gas method based on CFD is more suitable for exploring
the overpressure problem of vapor cloud explosion. Buildings arranged
perpendicular to the direction of blast wave have the most obvious
enhancement and weakening effect on overpressure, and the maximum
increase rate and decrease rate are about 90%. The maximum increase
rate of overpressure between two vertical layout buildings is more
than 60% higher than that between two horizontal layout buildings.
When determining the emergency evacuation path, the non-explosive
side of the building perpendicular to the shock wave layout should
be given priority. If it is necessary to pass through the building
gap, the gap between the two horizontal layout buildings should be
preferred to ensure that the damage of overpressure to personnel is
minimized. The research results can provide a theoretical basis for
the improvement of personnel safety control measures in high-consequence
areas of the gas pipeline.
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