No abstract

With the wide application of bolt connection, the application environment of the bolt is more and more complicated. The problem of bolt loosening caused by high temperatures cannot be ignored. Based on the research status of domestic and foreign experts, this paper analyzes the causes of high-temperature bolt loosening and introduces theoretical research on this problem. The conclusion is drawn that the factors affecting bolt loosening under high-temperature conditions and the anti-loosening measures are put forward.

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Hydrodynamic processes in compound channels are closely related to the cross-sectional geometry of the river. The cross-sectional shape of natural meandering rivers is always irregular, with a curved main channel (MC) and one or two floodplains (FPs), and most are confined within levees. The geometric shape of the cross-section of such rivers changes greatly in a flood, which influences the exchange of momentum and energy between the MC and FPs. Many previous studies have focused on flow mechanisms in compound meandering channels of relatively regular and simple cross-section, which is not representative of natural rivers. An experimental study of a sine-shaped meandering compound channel of irregular shape and with levees was thus conducted. Using detailed experimental data, the development of streamwise flow, secondary flow and turbulent shear stresses over the cross-sections were analysed. Special emphasis was placed on the momentum exchange between the MC and FPs. The results showed that flow transport in the MC plays a leading role and the momentum exchange between the MC and FPs is more intensive for a high water level. The formation, development and decay of secondary flow in compound meandering rivers are closely related to the momentum exchange between the FPs and the MC. Finally, transverse flow plays a dominant role in the process of momentum exchange and the effects of turbulence are negligibly small.