Abstract: The analysis of elasto-plastic solution can provide a basis for the stability research of cold regions tunnel. Therefore, the elasto-plastic damage mechanics calculation model was established by considering the non-uniform frost heave of surrounding rock. The unified analytical solutions of elasto-plastic stress field and displacement field of cold regions tunnel were derived based on the unified strength theory, and the unified solutions were verified and the parameters were analyzed. The results show that, by neglecting plastic damage and volume frost heave ratio of surrounding rock, the elasto-plastic solution of cold regions tunnel tends to be conservative, and the actual frost heave degree of surrounding rock for cold regions tunnel can be more accurately reflected by considering the non-uniform frost heave. In addition, the potential strength of frozen surrounding rock can be effectively improved by considering the intermediate principal stress effect. The radial stress σf of lining and plastic radius rp of tunnel are significantly influenced by parameters such as damage degree ratio λ/Ef, volume frost heaving ratio ξV, coefficient of non-uniform frost heaving k, unified strength theoretical parameter b, initial ground stress p0 and displacement release coefficient η. Hence, the influence of different parameters on tunnel engineering in cold regions should be reasonably analyzed. The research results can provide theoretical reference for engineering design of cold regions tunnel.

Key words: cold regions tunnel, damage, non-uniform frost heave, elasto-plasticity, unified strength theory, intermediate principal stress effect