针对高地应力区多场耦合作用对围岩塑性松动区的影响问题，依托实际工程，基于统一强度理论，建立多场耦合作用下围岩松动圈分析模型，研究初始地应力、地温、隧道开挖半径及中间主应力对围岩松动圈半径的影响。研究得到： 1）热-力耦合作用下，围岩初始地应力对围岩松动圈半径的影响起主要作用，且围岩松动圈半径与初始地应力呈非线性关系； 2）地温升高使初始地应力、隧道开挖半径及中间主应力影响系数对松动圈半径的影响变大； 3）松动圈半径随着隧道开挖半径的增大而近似线性增大，随着中间主应力影响系数的增大而减小，中间主应力影响系数越小，围岩稳定状态对中间主应力越敏感； 4）结合工程实例分析可知，在热-力耦合作用下，基于统一强度理论计算的围岩松动圈半径误差小于1.4%，证明所提出的计算方法是合理可行的。

The influence of multifield coupling action on the plastic loose circle of surrounding rocks in high ground stress zone is investigated using an analytical model. For this purpose, a case study is conducted, and the established analytical model is based on the unified strength theory. Furthermore, the influence of initial crustal stress, ground temperature, tunnel excavation radius, and intermediate principal stress on loose circle radius is examined. The primary findings of the study are as follows: (1) Under the thermalforce coupling effect, the radius of the loose circle is primarily affected by the initial crustal stress and has a nonlinearly relation with this stress. (2) An increasing ground temperature expands the influence of initial crustal stress, tunnel excavation radius, and intermediate principal stress on the loose circle. (3) The radius of the plastic loose circle increases almost linearly with an increase in the tunnel excavation radius and decreases with increasing intermediate principal stress coefficient. Moreover, the sensitivity of the stability state of the surrounding rocks to the intermediate principal stress increases with decreasing intermediate principal stress coefficient. (4) The engineering practice shows that the error of the calculated loose circle radius of surrounding rocks based on the unified strength theory is less than 1.4% under the action of thermalforce coupling, demonstrating the rationality and feasibility of the proposed calculation method.