At 9:00 on September 28, after 585 days of arduous efforts by the builders, the No. 1 and No. 2 tunnels of the newly built Chaohu-Ma'anshan Intercity Railway's Dacaoshan section were holed through simultaneously, marking the successful breakthrough of all tunnel works along the entire Chaoma Intercity Railway line. The project has made important progress, providing favorable conditions for subsequent girder erection and track construction.

A distant view of Dacaoshan No. 1 Tunnel.

The Chaoma Intercity Railway has six tunnels along its entire line, with a total length of 6,329 meters, mainly distributed in low mountain and hilly areas. The Dacaoshan No. 1 and No. 2 tunnels holed through this time are key and difficult projects in the construction of the entire line, located in Huanfeng Town, Hanshan County, Ma'anshan City. Among them, Dacaoshan No. 2 Tunnel, with a total length of 2,330 meters, is the longest tunnel on the entire Chaoma Intercity Railway. It is a double-track, single-tube ballastless high-speed railway tunnel designed for a speed of 350 kilometers per hour, with a designed cross-sectional area of 100 square meters and a maximum buried depth of about 106 meters. Grade IV and V surrounding rock accounts for more than two-thirds of the total, making it prone to risks such as collapse and falling blocks, which poses great challenges to construction technology, equipment, safety, and environmental protection.

The breakthrough site.

Since the construction of the Dacaoshan No. 1 and No. 2 tunnel projects began, the project construction management unit, Ning'an Railway Company, together with participating units such as China Railway No. 4 Engineering Group, China Railway Siyuan Survey and Design Group, and Beijing Modern Tonghao Supervision, has aimed to build safe and high-quality tunnel projects. They have carried out scientific planning, advance pre-control, optimized construction plans, coordinated resource allocation, and strictly controlled key links and processes. They adopted equipment such as self-propelled hydraulic invert trestles, intelligent information-based secondary lining trolleys, wet spraying manipulators, and semi-automatic cloth-hanging trolleys, and followed the construction principles of "advance pipe roof, strict grouting, short excavation, strong support, early closure, and frequent measurement," advancing construction in a scientific, orderly, safe, and high-quality manner and laying a solid foundation for the tunnels' breakthrough on schedule.

The Chaoma Intercity Railway starts at Chaohu East Station and runs eastward through Hanshan County, He County, Zhengpugang New Area, Dangtu County, the Economic Development Zone, Yushan District, and Huashan District before entering Ma'anshan East Station. The main line has a total length of 61 kilometers and a designed speed of 350 kilometers per hour. Five stations are set along the line: Chaohu East, Hanshan, Zhengpugang, Ma'anshan South, and Ma'anshan East. Among them, Chaohu East and Ma'anshan East are existing stations, while the other three are newly built stations.

Schematic diagram of the Chaoma Intercity Railway route alignment.