Large-diameter shield tunneling involves excavating a substantial section at significant depths and torques, which can disturb the surrounding rock and soil, particularly in regions characterized by intense karst development. Currently, research on the disturbance and deformation characteristics, stress mechanisms induced by tunneling, and deformation modes of karst caves and strata is limited. This paper investigates the stress mechanisms when large-diameter shield tunneling traverse karst-rich regions. To facilitate real-time monitoring of the surrounding rock pressure during shield tunneling, a novel monitoring method is proposed. By analyzing the real-time data, this study examines the stress patterns and mechanisms acting on the tunnel sidewall during shield tunneling. It is observed that the positive pressure on the tunnel sidewall typically increases and then decreases due to the soil chamber pressure exerted by the shield tunnel during excavation, resulting in a residual positive stress after tunneling is completed. Additionally, the lateral pressure on the tunnel sidewall experiences two distinct additional pressures. The first is due to the soil chamber pressure from the shield before the cutterhead reaches the area, and the second is induced by the synchronous grouting pressure during the assembly of tunnel segments. A residual lateral stress remains even after the shield tunnel has passed through. At a distance of 2.6 m from the tunnel sidewall, the additional total stress in the surrounding rock accounts for 39% of the initial horizontal geo-stress, while the residual additional total stress constitutes 30% of the initial horizontal geo-stress. This study provides a foundational understanding of the stability of karst cave sidewalls during large-diameter shield tunneling. Furthermore, it offers valuable data support for future large-diameter shield tunneling projects in areas with significant karst development and artificial structures.