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The coefficient of safety is an important index for the evaluation of slope stability. The safety coefficients calculated based on different instability criteria are significantly different, and the variability of the results will directly affect the evaluation of the stability state of slopes. In this paper, taking the step-type excavated slope of the Wanhuashan Trench Construction Project as the object, FLAC3D finite difference software was used to calculate the safety coefficient of loess slopes based on three different types of instability criteria, namely the calculation non-convergence criterion, the plastic penetration criterion and the displacement abruptness criterion, and to compare and analyze the differences, advantages and disadvantages of the evaluation results of the three criteria. The results of the study shows that there is a certain difference in the magnitude of safety coefficients obtained by using different instability criteria, with the order of magnitude being displacement abrupt change criterion > computational non-convergence criterion > plastic penetration criterion. The computational non-convergence criterion is easy to use and fast to solve, but does not show the change in the plastic zone of the slope during the discounting process. The plastic penetration criterion is not suitable as a criterion for slope instability on its own, but needs to be combined with the unbalanced force rate to be assessed, but it can show the area of shear damage and stretching of the slope. The sudden change of displacement criterion is tedious to solve, but the solution process truly reflects the critical damage state due to the change of slope displacement. For practical conditions such as loess slopes, it is recommended to use the fast computational non-convergence criterion to evaluate the slope stability in combination with the plastic zone penetration and the slope displacement change. [ABSTRACT FROM AUTHOR]

In order to improve the heat transfer performance of pulsating heat pipe, a new pulsating heat pipe combining Venturi section and pulsating heat pipe was proposed. The Venturi section was arranged in evaporation section, condensation section and adiabatic section respectively. The Venturi effect was used to promote the circulation of working medium in pulsating heat pipe, and the volume of fluid (VOF) model in fluent numerical simulation was used to study the heat transfer performance of the new closed-loop pulsating heat pipe (CLPHP) from the factors of pressure difference, temperature and so on. The results show that under the same heat flux, the start-up time of Venturi pulsating heat pipe is shorter than that of ordinary pulsating heat pipe, and the start-up time of No. 3 pulsating heat pipe (Venturi section is located in evaporation section) is the shortest. Under small input heat flux, the thermal resistance of Venturi pulsating heat pipe is less than that of ordinary pulsating heat pipe because it can maintain small amplitude oscillation for a long time. At 32 238 W/m², the heat exchange performance of No. 3 pulsating heat pipe is the best. When the input heat flux is greater than 32 238 W/m², the thermal resistance of Venturi pulsating heat pipe is greater than that of ordinary pulsating heat pipe. The research on the heat transfer performance of the new pulsating heat pipe provides a new idea for the optimal design of pulsating heat pipe with small input heat flux, and provides a design basis for engineering application. [ABSTRACT FROM AUTHOR]