各向异性片岩隧道支护结构承载力学特性研究

Bearing Mechanics Behavior of Supporting Structures in Anisotropic Schist Tunnel

为了更好地了解各向异性片岩隧道支护结构受力的分布特征规律,对武当群片岩隧道区不同片理面倾角的隧道围岩初期支护及二次衬砌承载特性展开了监控量测。通过对实测数据分析表明:围岩稳定后二次衬砌分担的围岩荷载远大于初期支护分担的围岩荷载,大部分二次衬砌分担的围岩荷载比高达80%~90%,这导致部分断面已超过了相关规范中关于软岩支护结构承载比例的规定,对二次衬砌后续运营稳定性会产生较大影响;片岩隧道支护结构受力表现出明显的各向异性特征,当片理面倾角<45°时,随着片岩片理面倾角的增大,支护结构稳定时水平侧受力呈增加趋势;当片理面倾角>55°时,水平受力呈较陡减小趋势;隧道支护结构不同部位受力相差较大且具有明显的非对称性,片岩隧道围岩及支护受力均存在顺层偏压特性。

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.