Abstract: To further investigate the convergence deformation mode of soft rock tunnel section in mountainous area, a case study is conducted on the crown settlement and horizontal convergence of arch waist of a tunnel section, the ratio 〖WT５《TNR#I》〗K〖WT５《TNR》〗 of crown settlement and horizontal convergence of arch waist is proposed based on the existing uneven convergence mode of metro shield tunnel, so as to parameterize the deformation of tunnel crosssection. Additionally, three forms of convergence deformation of tunnel crosssection are proposed based on 〖WT５《TNR#I》〗K〖WT５《TNR》〗 value. Finally, the monitoring data of tunnel crosssection deformation under different buried depths in Gansu section of the Ganqing tunnel on XiningChengdu highspeed railway are analyzed. The results show the following: (1) The parametric analysis of the 〖WT５《TNR#I》〗K〖WT５《TNR》〗 value shows that the deformation mode of the tunnel crosssection is mainly affected by the tunnel uniform convergence 〖WT５《TNR#I》〗〖ＱＸ（Ｙ８〗ε〖ＱＸ）〗〖WT５《TNR》〗 and the tunnel ovalization 〖WT５《TNR#I》〗〖ＱＸ（Ｙ１０〗δ〖ＱＸ）〗〖WT５《TNR》〗. (2) The buried depth of the tunnel has a certain influence on the convergence deformation of the tunnel crosssection after tunnel excavation. Because the surrounding rock of the tunnel is relatively stable under the condition of deep buried depth, the convergence deformation of the tunnel crosssection is small and tends to be stable in a short time. (3) The uneven convergence model and the existing empirical parameters are suitable for the tunnel crosssection in the shallow buried area (buried depth of 17.8~19.3 m), but the applicability of the tunnel crosssection in the deep buried area (buried depth of 48.5~49.3 m) is not good. (4) For the first time, the uneven convergence mode of the tunnel crosssection from the metro shield is introduced into the mountain tunnel. Due to the complexity of the mountain tunnel construction, the current research on the 〖WT５《TNR#I》〗K〖WT５《TNR》〗 value of the mountain tunnel is only a preliminary applicability study, which needs further study.

Key words: soft rock tunnel, uneven convergence mode, crown settlement, horizontal convergence, tunnel ovalization