为解决传统弹塑性力学理论在计算时未考虑实际围岩卸载时的扩容效应导致的位移设计值预测误差较大的问题，通过考虑不同应力状态下围岩损伤扩容系数的不同，建立圆形隧洞开挖松弛位移的分层总和法理论计算方法，提出以洞壁处围岩损伤扩容状态为控制值的围岩开挖位移预警值计算方法。结合分水江引水隧洞工程实例，对不同围岩级别、不同埋深、洞壁围岩的不同扩容效应（即不同支护状态）时圆形隧洞开挖后洞壁围岩位移变化规律进行分析，提出以圆形隧洞为基础的围岩预警值理论计算经验公式。由实际应用结果表明： 考虑扩容效应的围压位移分层总和法计算值比弹塑性理论计算值大3倍以上，计算结果更符合实际情况。

The design value of predicted displacement of surrounding rock calculated by traditional elastoplastic mechanics theory is large due to its ignorance on dilation effect during surrounding rock unloading. Hence, a theoretical calculation method of relaxation displacement of circular tunnel excavation by stratified summation method is established by considering the difference of damage and dilation coefficient of surrounding rock under different stress states; and a method for calculating the early warning value of surrounding rock excavation displacement is put forward, which takes the damage and capacity of surrounding rock at the wall of the tunnel as the control values. And then the displacement of surrounding rock of waterdiversion tunnel crossing Fenshui River is analyzed under the conditions of different grades of surrounding rocks, different buried depths, and different dilation effects (corresponding to different supporting states); and an empirical formula for calculating the early warning value of surrounding rock of circular tunnel is put forward. The calculated value of the method based on stratified summation of confining pressure displacement considering the dilation effect is more than three times larger than that calculated by elastoplastic theory, and the calculated results are more in line with the actual situation.