Application of In-Situ Protection Construction Technology for Existing Pipelines Crossing Large Cross-sections of Foundation Pits

With the booming development of subway construction in urban rail transit, it is inevitable to pass through dense buildings and large pipelines, especially during the construction of open cut stations or entrances and exits, underground pipeline protection issues are often encountered. Moreover, various types of underground pipelines involve multiple property rights units, take a long time to dismantle and modify, and require a large amount of coordination work. Often, due to the lack of timely relocation and modification of local pipelines, the construction period of the project is repeatedly delayed, wasting a great deal of manpower, financial resources, and material resources. If there is a problem where the foundation pit passes through the existing comprehensive pipe gallery, causing the pipeline to be unable to be relocated, it is necessary to dismantle the comprehensive pipe gallery and provide in-situ protection for the pipeline. Based on a real engineering project, analyzing common practices at home and abroad, research is conducted on the demolition and pipeline protection construction technology of the comprehensive pipe gallery. It successfully solves the problem of not relocating the comprehensive pipe gallery and internal pipe lines, allowing for normal excavation and construction of underground walls and deep foundation pits, ensuring the quality of underground wall construction and the safety of deep foundation pits. The practical results show that using this technology for construction can reduce the risk of underground tunnel excavation Φ The construction of 400 large pipe curtains reduced 87 tons of steel and 211 tons of cement, saving a total of 5.62 million yuan compared to traditional technology. In terms of construction period, it can save 15 days, minimizing the involvement of more ownership units in the pipe gallery and the large coordination workload, resulting in inability to relocate or delayed relocation, causing serious losses to the construction itself. This can provide reference and experience for other similar projects.