Experimental study on the effect of water gushing on loess metro tunnel

In the construction of metro tunnels, water gushing accidents caused by the rupture of underground pipeline often occur, and in loess area, the collapsibility of loess makes this problem more complex and difficult. To investigate the damage of metro tunnel caused by collapsible loess under the action of local dynamic water (gushing water), a model experiment was conducted based on the pipeline water gushing accident happened in the construction of metro tunnel located in loess area. Through the study of similar materials of loess and tunnel lining, the test materials and apparatus were prepared according to similarity criterion. By simulating water gushing environment in the loess stratum, this paper analyzed mechanical characteristics of tunnel (water pressure of surrounding rock, contact pressure and internal force of tunnel lining) and deformation of surrounding rock and tunnel. Furthermore, combining with the process of local collapse of loess in the model experiment, it is concluded that the formation of water transport channel is the main reason for the difference of tunnel structural response when water gushing occurs at different locations. Finally, a three-dimensional spatial model of water transport channel in loess stratum under the environment of local water gushing was established to study the rule of water transport.