浅埋偏压隧道穿越松散堆积体支护结构受力特性分析

为探究浅埋隧道穿越松散斜坡堆积体时的偏压特性，基于雅康高速日地1号隧道，建立了精确的三维数值模型，运用FLAC3D进行了施工过程的力学分析，并开展了隧道支护结构体系力学行为的现场测试，对其洞口段穿越滑坡堆积体时的围岩变形机理与支护结构非对称受力特性进行了深入研究。结果表明:隧道周边围岩的变形具有显著的非对称特性。初期支护承受较大的荷载，最大围岩压力出现在深埋侧。与变形和围岩压力分布的情况相反，二次衬砌的最大轴力出现在浅埋侧。隧道二衬的安全系数较低，需要较长的时间才能稳定，为了确保隧道运营期间的安全，应适当增加二衬厚度。

Analysis on Mechanical Properties of Supporting Structure of Shallow Buried Tunnel Passing through Loose Accumulation Body under Asymmetric Load

In order to analyze the asymmetric mechanical properties of the shallow buried tunnel passing through loose slope accumulation body, based on Ridi tunnel on Ya’an-Kangding highway, this paper established an accurate three-dimensional numerical model. Software FLAC3D was adopted to simulate the construction process. The results obtained from numerical method and field tests reveal that significant asymmetric deformation occurs in the surrounding rock. The primary support bears large compressive stress from surrounding rock. The largest load occurs at the deep buried side of the tunnel. Contrary to the distribution regulation of deformation and compressive stress from surrounding rock, the maximum axial force of secondary lining is located at the shallow buried side. The safety coefficient of secondary lining gradually declines for a long time. The values of which are rather small. To ensure the long-term safety of the tunnel, the thickness of the secondary lining should be enhanced to a proper degree.