Abstract: In the aim of better understanding the distribution of forces on the supporting structures in anisotropic schist tunnel, the bearing behavior of preliminary bracing and secondary lining of surrounding rocks with different schistosity plane angles in Wudang group schist tunnel area are monitored and measured. Analysis of the measured data reveals that the load shared by secondary lining is much greater than that by preliminary bracing when the surrounding rock is stable. Rock load shared by most secondary linings accounts for up to 80%-90%, which suggest that the bearing ratios of some sections exceed the standard in specifications, posing large impact on the stability of secondary lining in the subsequent operation. Supporting structure of schist tunnel shows obvious anisotropy. When the schistosity plane angles are less than 45°-55°, the lateral force when supporting structure is stable shows an increasing trend with the increase of schistosity plane angles, and a steep decrease when the schistosity plane angle is larger than 45°-55°. Forces of different parts of support structure are apparently different and obviously asymmetrical , and forces of surrounding rock of schist tunnel and supporting structure has consequent bias characteristics.

Key words: schist tunnel, anisotropy, monitoring and measurement, supporting structure, bearing behavior