Hefei, August 6 (Xinhua) — According to China Railway No. 10 Engineering Group Third Construction Co., headquartered in Hefei, Anhui, at around 20:00 Beijing time on the 5th, after 343 consecutive days and nights of relentless work, the Chancay Tunnel in Peru, constructed by China Railway No. 10 Engineering Group, was successfully holed through, completing the key milestone 10 days ahead of schedule.

Photo shows blasthole layout at the Chancay Tunnel in Peru.

　　The Chancay Tunnel is located in Chancay, Peru. The project includes one tunnel, one overpass, 10 connecting main roads, repair of buildings along the route affected by construction, municipal sidewalks, and more. The Chancay Tunnel has a total length of 1,839 meters and is a dual-direction, three-lane tunnel, with a single lane width of 3.5 m and a design speed of 60 km/h. The shallow-buried section is 1,168 meters long, accounting for 64.3% of the tunnel's total length, with a minimum cover depth of only 6.6 meters. It passes through several geological faults, large sand-pocket interbeds, sandy-layer/rock-layer geological bias-pressure strata, and aeolian sand strata; the aeolian sand section carries high risks of sand leakage and collapse. It passes beneath important structures including factories, substations, the old and new Pan-American Highway, an archaeological protection zone, communities, schools, churches, and a women's activity center. Moreover, geological exploration cannot be carried out in residential areas and the archaeological protection zone, resulting in unknown rock strata and repeated geological anomalies.

　　All Chinese and Peruvian staff of the project team overcame communication barriers and adopted measures of "ground-penetrating radar + advanced probe holes + endoscope" to identify weak surrounding rock, sand layers, faults, and other unfavorable geology in advance, promptly adjusting support methods and flexibly coordinating the sequencing of processes in different surrounding-rock sections, achieving "adapting to changes in rock conditions." In the drill-and-blast section of the tunnel, by closely linking construction processes and optimizing construction techniques, "zero-connection" and "negative-connection" between processes were achieved, realizing a maximum single-day advance of 16 meters and a monthly advance of over 400 meters, setting a new record for the construction of large-span three-lane tunnels abroad.

Photo shows an on-site inspection of the breakthrough quality at the working face of the Chancay Tunnel exit in Peru.

　　As an international project designed and constructed by a Chinese enterprise, the Chancay Tunnel project is a cooperation project jointly built by China and Peru under the Belt and Road Initiative. The project provided more than 1,500 jobs for local residents, with nearly 7,500 people benefiting indirectly.

　　Once completed, the Chancay Tunnel will help the Chancay Port achieve an annual bulk and general cargo throughput capacity of 6.2 million tons and an annual container throughput capacity of 1.5 million TEUs, which is of great significance for Peru in building the most influential logistics distribution center along the Pacific coast and promoting regional economic and social development.