This paper systematically studies the in-situ protection technology system under complex conditions where municipal road and bridge open-cut tunnels are adjacent to or pass through existing pipelines, under the condition that the pipelines do not need to be relocated. The key mechanism of the MJS technology in the reinforcement of the pit side wall and water sealing is analyzed, and the technical principles and implementation methods for controlling ground deformation and ensuring pipeline safety are clarified. The paper elaborates on the formulation of protection standards based on pipeline types and environmental conditions, the collaborative design of support systems, the collaborative construction mechanism among multiple units, and the construction and data application of high-precision real-time monitoring platforms. Through typical engineering cases, the effectiveness and limitations of key technologies such as MJS in practical applications are verified, providing practical basis and optimization suggestions for the safe and controllable protection of pipelines in similar open-cut tunnel projects.