Abstract:

During the construction of LijiangShangriLa Railway, large deformation of Triassic basalt is very serious. Hence, the deformation mechanism and causes are analyzed; and the supporting measures are determined. And then field test is carried out. Finally, tests are carried out on insitu strength, loose zone, mineral compositions, ground stress, deformation characteristics and internal forces of primary support and secondary lining of large deformation section. It is concluded that the following measures can effectively control the large deformation of basalt: (1) Increasing the curvature of sidewall and amount of reserved deformation. (2) Increasing the primary support steel frame model and lengthening the sidewall system bolt. (3) Shortening the closing time of primary support steel frame. (4) Controlling the primary support deformation velocity within 12mm/d when carrying out secondary lining.

Key words: railway tunnel, large deformation control, stress release, sidewall curvature, reserved deformation