China's First Subway Through Karst Spring Area Becomes Operational
JINAN (China), Dec 27 (Bernama-Xinhua) -- China’s first subway line to pass through a karst spring area began operations on Saturday in Jinan, east China’s Shandong Province, marking an engineering breakthrough that balances urban transport needs with the protection of natural water resources, reported Xinhua.
Subway Line 4 runs beneath one of Jinan’s busiest transport corridors, significantly reducing travel time and easing road congestion.
However, concerns about whether subway infrastructure could coexist with the city’s sensitive spring environment delayed construction for years, as many feared tunneling could disrupt groundwater flows from the southern mountains that sustain the northern springs.
Jinan is called the "City of Springs" for its roughly 1,000 natural artesian springs. However, its karst geology also makes it one of the most fragile environments for underground construction.
To address the complex geology, survey teams identified spring-sensitive zones and adjusted the route to avoid aquifers, increased tunnel depth and minimised impacts on water systems.
The construction team conducted comprehensive geological surveys, customised shield tunneling machines, and adopted earth pressure balance technology to prevent ground settlement.
At key stations, U-shaped groundwater diversion channels were installed to maintain natural water flow.
Monitoring data show that the water level of the iconic Baotu Spring recently rose to 30.32 metres, the highest level recorded since 1966.
"This demonstrates that our spring protection measures and innovative engineering approaches are scientifically effective," said Huang Yongliang, a senior engineer for spring protection from Jinan Rail Transit Group Co., Ltd.
A karst spring area is a place where groundwater naturally emerges at the surface from a karst landscape – a type of terrain formed by the dissolution of soluble rocks such as limestone, dolomite, or gypsum.
A “karst spring area” usually highlights geological sensitivity, potential flooding risks, or water-source protection concerns.
--BERNAMA-XINHUA
