Numerical Analysis for Appropriate Buried Depth of Cold-Proof Drainage Hole of a Tunnel

Abstract

Based on the MIDAS/GTS finite element analysis software, taking a tunnel in Qinghai province as an example, fixing the position of main tunnel and holing through, just adjusting the buried depth of the cold-proof drainage hole, the change rules of displacement, stress and plastic zone in different buried depths of cold-proof drainage hole are analyzed. The influence of different buried depths for cold proof drainage hole on the structure of main tunnel is revealed. The result shows that (1) the influence between main tunnel and cold-proof drainage hole is mutuality; (2) from the point of displacement change rule, the optimal effective buried depth for the cold-proof drainage hole of a tunnel in Qinghai province is from 5 m to 6 m; (3) from the point of stress change rule, the optimal effective buried depth for the cold proof drainage hole is also from 5 m to 6 m; (4) bases on the stress homogeneity of the support and the material, from the point of plastic zone change rule, the optimal effective buried depth for the cold-proof drainage hole is from 4 m to 6 m; (5) eventually, on the basis of comprehensive consideration of the largest frozen depth, requirements of safe and economy, and influencing factors of construction of tunneling engineering area, the proper effective buried depth of the cold-proof drainage hole is confirmed to be 5 m, i. e., the proper buried depth of the cold-proof drainage hole is confirmed to be 8 m.