When tunneling in high geostress region

the surrounding rock often produces obvious rheological deformation. The deformation would lead to stress concentration at the connection between side wall and inverted arch

which might result in floor heaving during tunnel operation period. So

a reasonable section shape of tunnel which could reduce stress concentration is very important for the long-term stability of tunnel. Considering rheological effect of surrounding rock

the parameterization design of tunnel section is programed into ABAQUS by Python. And a tunnel section optimization algorithm is established based on combination penalty function and Nelder-Mead function. An optimized objective function is established for Xiakou tunnel considering excavation area

floor heaving

creep damage area

axial force and bending moment of supporting system. The optimization results will provide scientific guidance for high geostress soft rock tunnel.