تحليل پايداري دامنه تونل 61 راه آهن شمال با استفاده از نرم افزارهاي FLAC و CLARA

Slope Stability Analysis of Tunnel No. 61 in Northern Railway Route using FLAC & CLARA Software

Observing authorized slope in the railway route makes the use of tunnel in mountainous areas inevitable. Tunnel No. 61 of the Northern railway has been constructed in the slope of Simindarah mountains within the weathered rocks of the lower part of Qom formation consist of Sandstone, marl and shale with interlayer of gypsum, anhydride and salt in the length of 308m and the portal width of 5m. The tunnel route is located on the north limb of a superimposed anticline cut by a strike-slip fault and is seismio-tectonically active. Considering the local landslides on the slope and the possibility of slide and security concerns on the slope where the tunnel is located are the subjects of the present study. In order to analyze the stability of the slope, a number of cross-sections were considered on the route of the tunnel and analyses were conducted on these sections. These sections were analyzed with CLARA software (limit equilibrium method) and FLAC software (numerical method). The sensitivity of the shear strength parameters on stability was also studied in detail. The geometry of the sections is approximately identical and from among the selected sections, the D-D section shows the critical status due to low shear strength. Considering the sensitivity analysis, if the shear strength parameters reach the limit where the slope may come close to sliding, the tunnel structure will be at serious risk in sections near the entrance and exit parts.