During the golden construction period in April, the construction site of Yujiu Road Station on the eastern extension of Hefei Rail Transit Line 2 is bustling with roaring machines and flying welding sparks, creating a scene of intense activity. More than 100 construction workers are orderly and focused on their work, making full preparations for the first shield machine to be launched for tunneling in early June, which also means that Hefei's Phase III construction projects are about to enter a new construction stage.

Phase III Construction Planning Projects Set Off a Construction Boom

The launching section for the first shield machine on the eastern extension of Line 2 is the right line between Feidong Railway Station and Yujiu Road Station. To ensure the smooth launching and tunneling of the shield machine, the Municipal Rail Transit Group led all participating units to carefully coordinate and deploy in advance, continuously optimizing the hoisting, launching, and receiving plans for the shield machine, organizing multiple expert reviews and demonstrations, scientifically organizing construction activities such as high-pressure jet grouting pile reinforcement at the end wells, gantry crane installation, slurry mixing station construction, launching base installation, and track laying, strengthening safety risk and hidden danger investigations, and making various guarantees for the safe launching and smooth tunneling of the first shield machine.

Since the official start of construction at Yujiu Road Station on the eastern extension of Line 2, various engineering projects have been rapidly advancing: traffic diversion and enclosure closure completed in 7 days, the first station's retaining piles on the entire line completed in 37 days, and the main earthwork excavation of the station completed in 55 days.

At the same time, civil construction on the southern extension of Line 3 and the southern extension of Line 4 is in full swing.

Currently, on the southern extension of Line 3, 3,249 retaining piles have been completed, accounting for 76% of the total; 45 diaphragm walls have been completed, accounting for 24% of the total; retaining piles at 3 stations have been closed, 3 stations have entered the foundation pit earthwork excavation stage, and the first main structure construction has begun, with earthwork excavation at 1 station already completed.

On the southern extension of Line 4, 899 bridge piles have been completed, accounting for 80% of the total, and 1,749 main retaining piles have been completed, accounting for 80% of the total; all 3 underground stations have started retaining pile construction, and pile foundations at 3 elevated stations have been completed and entered the cap and pier column construction stage.

The first phase of Lines 6, 7, and 8 are also advancing rapidly.

Multiple Measures to Ensure Construction Progress

Since the start of the Phase III construction planning projects on September 29, 2020, under the strong leadership of the Municipal Party Committee and Municipal Government, and with the strong support of district (county) governments and relevant municipal departments, the Municipal Rail Transit Group has led all participating units to overcome difficulties, conquering numerous challenges with the perseverance to open roads through mountains and build bridges over rivers, and properly resolving issues such as land acquisition, pipeline relocation, and traffic diversion. The Municipal Rail Transit Group has repeatedly communicated and coordinated with multiple external units, continuously improving design and construction plans, and preliminary coordination work has progressed smoothly.

The foundation pit for the ventilation shaft between Qingnian Road Station and Yungu Road Station on the southern extension of Line 3 is located east of Paihe Avenue, a major urban arterial road with heavy traffic, and adjacent to the Paihe River with complex groundwater conditions. The excavation depth of the ventilation shaft foundation pit is 36 meters, making it the deepest foundation pit among the under-construction sections of the Phase III construction planning projects, with great construction difficulty.

To ensure the construction progress of the ventilation shaft foundation pit and complete the project milestones on schedule, Wang Daorong, Deputy Secretary-General of the Hefei Municipal Government, Director of the Office, and Director of the Office of the Municipal Rail Transit Construction Leading Group, went to the site for scheduling. With the support of the Feixi County Government, the Municipal Rail Transit Group organized relevant units to hold multiple coordination meetings and successfully completed the relocation of the site, creating favorable conditions for the ventilation shaft construction.

Yilijing Station on the first phase of Line 8 is close to the existing Fuyang North Road Viaduct, with the viaduct deck railing approximately 1.09 meters from the main foundation pit at the closest point, posing a high risk for rebar cage hoisting.

To ensure hoisting safety, the Municipal Rail Transit Group organized multiple reviews of the rebar cage hoisting plan near the viaduct and invited experts in related fields to provide guidance. Innovative construction techniques were adopted according to local conditions, using a combination of trench cutters, rotary drilling rigs, and double-wheel milling for trenching. The upper soft strata were constructed with trench cutters; upon encountering hard rock, large-power rotary drilling rigs were first used to drill to the design depth, followed by trench milling machines. To date, 9 diaphragm wall panels have been successfully completed.

Meanwhile, to improve the efficiency of rail transit engineering construction, Hefei's first centralized rebar processing and intelligent manufacturing base was established in the Luyang Industrial Park. The base is divided into two branches, south and north, with a total area of 10,000 square meters. It adopts permanent fixed workshops, introduces advanced domestic intelligent CNC rebar processing equipment, and is equipped with dedicated dual-head welding robots and sorting robotic arms, enabling mechanized and assembly-line operations for rebar shearing, bending, and thread rolling. With more than 30 CNC rebar processing equipment and a complete intelligent CNC rebar processing management system, under the premise of fully ensuring quality and safety, the annual output can reach 120,000 tons.

Line 4 Expected to Complete Tunneling by End of June

In addition to the Phase III construction planning projects, other rail transit construction projects are also accelerating. Among them, Line 4, which will start initial operation by the end of this year, is making a concerted effort. The main structures of all 31 stations on the entire line have been capped; 60 out of 62 shield single-line sections have been completed, with tunneling expected to be completed by the end of June; short rail laying on the western section of Line 4 has been completed, and track laying on the eastern section is underway; the cumulative output value completed for the entire line is 10.13 billion yuan.

On the northern section of Line 5, the main structures of 10 stations have been capped, with 3 remaining; 14 single-line sections have been successfully completed, and shield tunneling has cumulatively completed 64.9% of the total; the cumulative output value completed is 2.09 billion yuan.

On the first phase of Line 1, the main structures of 2 stations have been capped, with 1 remaining; 4 single-line sections have been completed, and shield tunneling has cumulatively completed 65.4% of the total; the cumulative output value completed is 960 million yuan.