Mechanical characteristics and deformation law of tunnel in diatomite considering various softening conditions

At present, the research considering multi-factor softening conditions is rarely performed, and the research on the deformation law and mechanical properties of the tunnel in diatomite is even rarer. Diatomite is easy to soften in water, and its physical and mechanical properties change greatly after softening. Therefore, take the high-speed railway tunnel that passes through the diatomite stratum in East China as an example, considering various softening conditions (including softening degree and softening position), the deformation law and mechanical characteristics of the tunnel are obtained, and corresponding suggestions are also put forward according to different softening conditions. The results show that the deformation law and mechanical characteristics of the tunnel are greatly affected by the symmetry of softening part. The deformation of the inverted arch caused by the lower surrounding rock softening of the tunnel is the largest, and the maximum stress occurs at the arch foot when the upper surrounding rock of the tunnel softens. Different softening degrees and positions have a great influence on the mechanical characteristics and deformation law of the tunnel. The results obtained in this paper may provide some important references for similar projects in the future.