Yinzishan Tunnel on Yan’an–Yulin High‑speed Railway breaks through

According to China Railway Group Limited, published on 13 November 2026, the Yinzishan Tunnel on the Yan’an–Yulin high‑speed railway, built by China Railway Tunnel Group under China Railway Group, was successfully broken through on 10 November.

The tunnel lies across Qingjian and Suide counties in Yulin, Shaanxi Province. It stretches for 5,035.04 metres and is designed as a single‑bore, double‑track tunnel, with a maximum overburden of 148 metres and a minimum overburden of only 2 metres. It sits within a loess ridge and gully zone marked by steep, undulating terrain. Sinkholes are widespread above the tunnel alignment, while loess landslides, ground fissures and shallow surface collapses frequently occur alongside gullies. Collapsible loess formations appear near the tunnel portals, creating demanding construction conditions.

The construction team adopted the drill‑and‑blast method for excavation. Blast parameters were refined and work sequences rationalised, with tunnelling advancing from both ends of the alignment. The fastest recorded excavation rate reached 150 metres per month. For shallow sections and fractured rock, crews restricted excavation advance, strengthened advance geological forecasting and monitoring, and adjusted support parameters promptly to maintain safe passage. A digital intelligent control platform supported on‑site management, lifting safety standards and construction efficiency. The tunnel was completed two months ahead of schedule.

The Yan’an–Yulin high‑speed railway forms a key segment of the Baotou–Yinchuan–Haikou corridor within China’s eight vertical and eight horizontal high‑speed rail network. It provides a dedicated passenger route linking western Inner Mongolia and northern Shaanxi with the Guanzhong plain, south‑western and south‑central regions. Once opened, the railway will back the ecological conservation and high‑quality development of the Yellow River basin, foster fresh momentum for the large‑scale development of western China, and upgrade transport infrastructure along the route.