Based on the construction collapse case of a hidden excavation tunnel near the ground fissure area of Xi'an Metro Line 3, the hydrogeological and construction behavior factors causing the collapse are analyzed. By further simulating the process of tunnel collapse using discrete element software, it is found that the initial support structure in the upper part of the tunnel accelerates the formation of the "force chain". In the collapse case, a series of treatment measures are taken to ensure the safety of the soil layer structure, without causing secondary disasters. The on-site monitoring data effectively verifies the effectiveness of the risk management plan. The research results indicate that surface precipitation is an important cause of collapse, and when excavating tunnels in weak strata, it is necessary to ensure that the tunnel structure forms a ring as soon as possible and ensure the stability of the bottom soil.