巷道开挖后，破坏了原有的平衡状态，发生应力重分布，当超过围岩的承载能力时，必然会引起围岩破坏甚至地下岩体的整体失稳。在这种情况下，应设置初期支护。但是现在仍缺少对支护参数的准确的理论计算，最多地还是借助于经验类比法，这样就造成支护的安全性不够或不够经济。基于Mohr-Coulomb准则，分析了初期支护与围岩的耦合作用问题，提出了更加安全经济的设计方法，可以对工程的设计和施工提供更加可靠的理论依据。

After the tunnels are excavated, the original state of surrounding rock is destroyed. If the bearing capability of surrounding rock is not enough, the surrounding rock may be damaged and the whole underground rock mass lose even its stability. In the case, the primary support must be installed. But there is still lack of the accurate calculation about support parameters, so the empirical method is always relied on, which leads to the unsafe and uneconomical support. Based on MohrCoulomb criterion, the coupling interaction of primary support and surrounding rock is studied, and the more safe and economical design method is presented in this paper.