Analysis of Mechanical Performance of Double-Arch Biological Channel in the Operation Period considering the Effect of Fluid-Solid Coupling

In order to solve the problem that highway development needs to cross environmentally protected areas, which results in the cutting off of wildlife habitats and fragmentation of the biosphere, on-road biological passages are established in many places. This paper carries out a numerical analysis of the biased load, caused by the backfill of the biological channel, the environment, and the seepage problem of the backfill under rainfall conditions. By comparing the pore water pressure’s test data in backfill with the modeling result data, the influence law of biased pressure load on open hole lining during running period, and the law of water pressure change are derived. The analysis shows that: (1) the backfill soil has a restraining effect on the double-arch tunnel, and the side arch ring’s deformation of the backfill decreases with the increase of the height of the backfill; when backfilling on both sides is flush with the top of the cave and continuing to backfill at the cave’s top, the arch ring near the higher mountain deforms greater because of the mountain’s pressure. (2) The internal force of the channel and the temperature are closely relevant, and the value is gradually stable without the influence of construction or other causes. (3) Pore water pressure variation correlates with seasons: the water pressure is lower in winter and higher in summer. After the pore water is saturated, the monitoring data does not change with the increase of rainfall.