Recently, the auxiliary renovation project for the Shenzhen Metro Line 20 project, undertaken by The Sixth Engineering (Xiamen) Co., Ltd. of CCCC Third Harbor Engineering Co., Ltd., passed acceptance. The construction scope included the addition of a direct elevator at Exit B of Gaoxin Yuan Station and the construction of temporary Exits C and D.

Gaoxin Yuan Station is located in the city's core area. During this phase of construction, the project team faced multiple challenges, including significant interference from the operation of existing lines and short time windows for portal excavation. To overcome these difficulties, the project team decomposed tasks and set reverse schedules with clear responsibilities assigned to individuals. They formulated a construction organization plan featuring "staggered peak construction in different time periods + temporary isolation." This approach reduced the impact on existing lines while ensuring controlled safety and orderly progress.

At the start of construction, supplementary investigations revealed a conflict between a water supply pipe and the retaining structure on the north side of the new direct elevator at Exit B. Technical personnel immediately optimized the elevator structure based on the actual location of the existing water pipeline. This made full use of the existing structure, reducing construction costs and saving significant time for subsequent work.

The excavation depth for the temporary Exit C reached 14.7 meters, the deepest in this auxiliary renovation project. The groundwater level in this area is high, posing a significant risk of water ingress during deep excavation. The project team studied the site's geological and hydrological conditions, strictly controlled the quality of dewatering well construction, and rigorously inspected the quality of well pipes and filter materials. During excavation, technicians strengthened monitoring of the groundwater level and surrounding buildings, adhering to the principle of "dewater first, excavate later" to ensure the safety of the excavation pit and adjacent structures.

The minimum distance between the excavation pit for temporary Exit D and the existing structure was only 8.2 meters. Furthermore, the connection point was located in gravelly sand and silt layers, presenting substantial construction risks. The project team developed a specialized construction plan and repeatedly conducted safety and technical briefings for each shift of on-site workers. During the construction involving opening connections into the existing exit passageway, measures such as grouting reinforcement of the peripheral strata using small conduits, interception and drainage during pit excavation and connection work, and hole drilling using water-jet drills were employed. These measures mitigated the risk of disturbance to the adjacent existing structure, ensuring the safety and quality of the critical node construction.

Based on the site conditions, the project team will focus on managing passenger flow guidance for the temporary exits and intensively pursue the construction of main structural elements, such as diaphragm walls, striving to complete the annual targets and tasks.

Content provided by: Zhang Jin