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Buried pipeline, as one of the crucial facilities of airport ground engineering, has been extensively utilized for the transportation of petroleum, natural gas, industrial wastewater, and more. However, there are significant gaps in the research on the dynamic response of buried pipelines in airports under the action of dynamic traffic loads, which severely hampers the design and engineering quality of oil transmission pipelines. This study builds a three-dimensional finite element model to simulate the action of vehicles on the pipe–soil structure with actual loads. Moreover, the current research establishes a dynamic analysis model of pipe–soil interaction to analyze the material damping and load parameters. Using the structural dynamic response equation and Rayleigh damping calculation theory, this study investigates the change law of pipe dynamic stress and influencing factors and presents the recommended values of the parameters related to the pipe–soil interaction. Results are as follows. A damping ratio of 0.05 can enhance the time lag of the dynamic response of the structure and weaken the response peak. For the Rayleigh damping parameters, the viscous damping coefficient α has almost no effect on the dynamic response of the pipe–soil structure, so it can be disregarded in the calculation. With the increase of the axial weight of the traffic load above the pavement structure, the peak value of each dynamic response quantity of the pipe–soil structure and load magnitude. The suggested value of the dynamic load coefficient of the pipe–soil structure is 1.5. Lastly, the earth pressure and dynamic load coefficients are suggested to take values for different load and axle type cases. [ABSTRACT FROM AUTHOR]

Background-Critical limb ischemia (CLI) is one of the most severe peripheral artery diseases. Angioplasty and bypass surgery are two major approaches for the treatment of CLI, however, it remains unclear which treatment has better benefit/risk ratio. In this paper, we performed a meta-analysis on the available clinical trials to compare these two approaches in terms of mortality, amputation-free survival, 5-year leg salvage, and freedom from surgical re-intervention. The results of this article will provide evidence based information for clinical treatment of CLI. Method-Randomized clinical trials comparing results between angioplasty and bypass surgery in CLI were identified by searching Pubmed (2000-2014) and EMBASE (2000-2014) using the search terms "angioplasty" or "bypass", "CLI" and "clinical trials". Primary outcome subjected to meta-analysis was amputation (of trial leg) free survival in 5 years. Secondary outcomes were 30-day mortality; mortality, re-interventions and leg salvage in 1, 3 and 5 years. Results-Seven clinical trials were selected for meta-analysis. No significant difference was found in the primary outcome-amputation free survival, between angioplasty and bypass surgery groups. The amputation free survival in 1, 3 and 5 years were 332/498 (66.7%), 169/346 (48.8%) and 21/60 (35%) in angioplasty group, versus 484/749 (64.6%), 250/494 (50.6%) and 46/132 (34.8%), in bypass group, respectively. The 30 days mortality rate was significantly higher in bypass treatment group [79/1304 (6.1%)] than in angioplasty group [30/918 (3.3%) [95% CI 0.55 [0.36, 0.86], P=0.008). However, there was no statistical significance in 1, 3 and 5 years mortality between these two groups. Two clinical trials showed that there was no difference in leg salvage between angioplasty and bypass surgery groups either. In addition, no difference was observed in re-vasculation between the two groups. Conclusion-Angioplasty is non-inferior to bypass surgery in regarding the amputation free survival, re-vasculation, leg amputation and overall mortality. However, angioplasty is safer, simple, and less invasive and less cost procedure. It should be considered as the first choice for feasible CLI patients.