为了研究深部软岩巷道开挖卸荷作用下的力学响应量及大变形失稳机理，基于统一强度准则和岩石三线段力学模型，建立了巷道围岩开挖卸荷力学模型，依据巷道开挖后围岩次生切向应力、等效剪应力分布特征，将围岩力学结构划分为浅承载圈、深承载圈、自稳承载圈、主承载圈和关键承载圈，通过理论分析，求解得到软岩巷道开挖后次生应力场、位移场以及软化区与破碎区范围解析解，结合某软岩工程相关力学参数，分析了巷道开挖卸压作用下围岩屈服应力，围岩破裂区、软化区影响范围以及围岩承载结构的影响因素。研究表明：围岩屈服应力随着初始黏聚力和内摩擦角的减小以及掘进速度的增大而减小，围岩越容易达到屈服发生破坏；围岩软化区范围与围岩初始力学参数相关，初始黏聚力越大的围岩，围岩软化区范围减小；破碎区范围随着黏聚力软化模量、剪胀角、掘进速度以及支护结构间排距等的增加而增大；主承载圈和关键承载圈的范围、径向应力和轴向应力的峰值随着围岩软化程度的增加而增大，且向巷道深部转移。

In order to study the mechanical response and large deformation instability mechanism of deep soft rock roadway under excavation unloading effect， the excavation and unloading mechanical model of surrounding rock of roadway is established based on the unified strength criterion and rock three line segments mechanics model.According to the distribution characteristics of secondary tangential stress and equivalent shear stress of surrounding rock after roadway excavation， the mechanical structure of surrounding rock is divided into shallow bearing circle， deep bearing circle， stable-self bearing circle， main bearing circle and key bearing circle.Through theoretical analysis， the analytical solutions of secondary stress field， displacement field and the scope of softened zone and broken zone are obtained after the soft rock roadway excavation.Combined with the mechanical parameters related to a soft rock roadway， the influencing factors of surrounding rock yield stress， surrounding rock fracture and softened zones and surrounding rock bearing structure under the roadway excavation unloading are analyzed.The results show that the yield stress of surrounding rock decreases with the decrease of initial cohesion and internal friction angle and the increase of excavation speed，and the surrounding rock is more likely to yield and damage.The scope of softening zone of surrounding rock is related to the initial mechanical parameters of surrounding rock， and the scope of softening zone of surrounding rock decreases with the increase of initial cohesion.The scope of fractured zone decreases with the softening modulus of cohesion，shear expansion angle and excavation speed.The range of the main bearing circle and the key bearing circle， the peak value of the radial stress and the axial stress increase with the increase of the softening degree of surrounding rock， and transfer to the roadway radial depth.