The secondary support structure and the enclosing of the lining must be established in time to improve the performance of the lining.

④对于浅埋大断面大跨度连拱隧道，应及早施作二衬，封闭成环，以改善结构受力。

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Then, theoretical study was carried out on the rheology of Jinchuan rock mass and a nonlinear rheological model was established. The best secondary support time was found by fitting.

然后，针对金川岩体的流变特征进行了理论研究，建立了非线性流变模型，通过拟合得出了最佳二次支护时机；

youdao

Then, theoretical study was carried out on the rheology of Jinchuan rock mass and a nonlinear rheological model was established. The best secondary support time was found by fitting.

然后，针对金川岩体的流变特征进行了理论研究，建立了非线性流变模型，通过拟合得出了最佳二次支护时机；

youdao