为评估隧道塌方处理过程中初期支护结构的安全稳定性，首先对某大断面铁路隧道Ⅳ级围岩塌方处理方案进行描述，通过涌入隧道内的塌方量预估隧道上方坍塌空腔高度，并初步探测出塌体位于隧道上方的高度，加上混凝土填充高度，同时考虑一定的安全系数，计算松散体岩土柱作用于隧道初期支护结构上的垂直荷载强度；然后采用荷载-结构模型，运用ANSYS软件对处理后的初期支护结构进行承载内力模拟，同时结合《铁路隧道设计规范》对其进行安全性评估，为施工方案的确定提供理论依据和决策支持；最后在安全评估的基础上，选择合理的初期支护结构，确保后续隧道施工安全及结构稳定，同时给出塌方段施工安全措施。

The treating scheme of collapse of surrounding rock of Grade Ⅳ of a large crosssection railway tunnel is described. The distance between collapse cavity and the tunnel is predicted and detected according to collapse volume; and the vertical stress on the primary support structure of the tunnel induced by rock and soil is calculated. The bearing internal force of the primary support structure of the tunnel is simulated by means of ANSYS software and loadstructure model; and the safety evaluation of the primary support structure of the tunnel is made according to Code for Design of Railway Tunnel. Finally, rational primary support structure is adopted and safe construction technologies for collapse section are provided.