Numerical Analysis of Deformation Characteristics of Surrounding Rock in Mudstone Dolomite Composite Stratum Tunnel

Composite strata are a special type of geology commonly encountered during tunnel construction, and are prone to geological hazards such as rock deformation and collapse during construction due to the vast differences in geotechnical, engineering and hydrogeological characteristics between the strata. Therefore, the analysis and study of the deformation characteristics of the surrounding rocks of tunnels with composite strata is carried out to address the situation of uneven deformation during the construction of tunnels with composite strata. This paper relies on the project of the new Chengkun Railway Teermo Tunnel, through data collection and analysis, laboratory tests, numerical simulation and other methods to analyse and study the serious uneven deformation during the construction of the tunnel with composite strata. The results of the study are as follows: (1) The engineering geological conditions of the Termo tunnel area were identified, mainly including the geological conditions of the area, topography, geological formations and hydrogeological conditions; (2) The physical and mechanical parameters were obtained by means of indoor experiments, laying the foundation for subsequent modelling using FLAC3D; (3) Combined with the actual Telmo tunnel project, the dip angle, percentage, depth of burial and pore water pressure of the composite strata were selected as variables, and FLAC3D was used to simulate the tunnel excavation of the composite strata under different parameters, and to analyse the deformation characteristics of the surrounding rocks and the variation law of each deformation index.