Based on the engineering practice of large cross-section highway tunnel, this paper reveals the space-time coordinated evolution law of the construction mechanical characteristics and deformation distribution of the support structure in the construction by half bench CD method through field test. At the same time, the mechanical response calculation model of the supporting structure in the partial excavation is constructed, and the mechanical characteristics of the support structure in the partial excavation process are analyzed by above mechanical calculation model. Then, the mechanical and deformation distribution of the feet-reinforcement bolt in the steel frame—foot-reinforcement bolt combined support system is analyzed under different levels of surrounding rock load and different structural parameters of the feet-reinforcement bolt. The research results show that: (1) The internal force of the supporting structure changes most obviously during the excavation of Part Ⅰ, Part Ⅱ and Part Ⅲ, and the internal force of the support structure gradually tends to be stable after a slight increase in the excavation of Part Ⅳ and Part Ⅴ; (2) The horizontal deformation and vertical deformation of the support structure mainly occur in the excavation process of Part Ⅰ, Part Ⅱ and Part Ⅲ, and the excavation of Part Ⅳ and Ⅴ has little effect on the deformation response of the structure. The vertical displacement of the supporting structure is larger than the horizontal displacement, and the dynamic response of the temporary diaphragm structure during tunnel excavation is shrinkage-expansion-shrinkage-expansion; (3) The bending strain of each measuring point decreases with the increase of the distance from the loading point, and the bending strain of section 1 and section 2 is much larger than that of the other three sections; (4) With the increase of the angle, the section position with strain close to 0 gradually moves to the deeper position of the bolt, and the axial strain of each section on the bolt gradually changes from positive strain to negative strain.
To prolong the life of cartridge retaining pawl and link stopper in a gun cartridge retaining Mechanism, three compression springs stiffness are reduced via design study and optimization design based on dynamic analysis. Presenting the load of shell on a typical stage while entering-bore, differential equations of motion in this mechanism are established. With translational velocity of shell as the design variable, a design research and simulation analysis are made. And the relationship between shell velocity and proper shell-feed is acquired. An evaluation function is built using springs stiffness with preference-selection. With this evaluation function as the optimum objective, spring stiffness as design variables, and proper shell-feed as constraint condition, the minimum of three spring stiffness is obtained after calculation. The results indicate that compared with the original design parameters optimization results, are significantly improved with the stiffness decreased separately by 20.27%, 11.99% and 6.86%.
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