Due to the difference in stress paths between the loading and unloading conditions, it is unsuitable to apply mechanical model under loading condition to stability of tunnel excavation.

• 由于岩体在加载和卸载条件下应力路迳的不同，仅采用加载条件下所建立的力学模型来研究隧道的开挖稳定性问题是不适合的。