ABSTRACT
Due to the ability to utilize the strength of the surrounding rock to enhance bearing capacity, tunnel-type anchorages have been consistently utilized in suspension bridges. Nevertheless, a close interaction occurs between the tunnel and the tunnel-type anchor when a highway tunnel is connected to a suspension bridge. This study employed numerical simulation and theoretical analysis based on the G317 Line Huangjiayuan tunnel and Zipingpu Bridge tunnel-type anchorage project, focusing on this specific type of adjacent engineering. Firstly, the discriminant degree of adjacent influence suitable for the interaction between the tunnel-type anchorage and the tunnel structure is established. The calculation conditions are distinguished by the influencing factors determined in the discriminant. The interaction law between tunnel-type anchorage and pre-built tunnel structure is further obtained. Using the method of curve regression, based on the criterion of proximity influence degree, the partition of mutual influence degree between the tunnel-type anchorage and the tunnel structure is obtained. At the same time, it is concluded that under the original design condition, the displacement degree of the tunnel structure will be greatly affected, and the tunnel structure is located in the strong influence area. According to the partition result, under the benchmark engineering geological condition, it is suggested that the angle of intersection between tunnel anchorage and tunnel structure should be increased to 3.3° and the anchor body inclination should be increased to 44°.
ABSTRACT
Flame extinction is one of the most essential critical flame features in combustion because of its relevance to combustion safety, efficiency, and pollutant emissions. In this paper, detailed simulations were conducted to investigate the effect of H2 addition on dimethyl ether spherical diffusion flame in microgravitational condition, in terms of flame structure, flammability, and extinction mechanism. The mole fraction of H2 in the fuel mixture was varied from 0 to 15% by 5% in increment. The chemical explosive mode analysis (CEMA) method was employed to reveal the controlling physicochemical processes in extinction. The results show that the cool flame in microgravitational diffusive geometry had the "double-reaction-zone" structure which consisted of rich and lean reaction segments, while the hot flame featured the "single-reaction-zone" structure. We found that the existence of "double-reaction-zone" was responsible for the stable self-sustained cool flame because the lean zone merged with the rich zone when the cool flame was close to extinction. Additionally, the effect of H2 addition on the cool flame was distinctively different from that of the hot flame. Both hot- and cool-flame flammability limits were significantly extended because of H2 addition but for different reasons. Besides, for each H2 addition case, the chemical explosive mode eigenvalues with the complex number appeared in the near-extinction zone, which implies the oscillation nature of flame in this zone which may induce extinction before the steady-state extinction turning point on the S-curve. Furthermore, as revealed by CEMA analysis, contributions of the most dominated species for extinction changed significantly with varying H2 additions, while contributions of the key reactions for extinction at varying H2 additions were basically identical.