The Yun-Kun High-Speed Railway is a high-speed railway connecting Chongqing and Kunming in Yunnan Province. It spans nearly 700 kilometers, with 21 stations and a design speed of up to 350 kilometers per hour. Construction of the Yun-Kun High-Speed Railway began on September 29, 2019, in the Chongqing and Sichuan sections, and the Yunnan section officially commenced on December 20, 2019.

　　The Junlian Tunnel in the Chongqing-Sichuan section of the Yun-Kun High-Speed Railway is being constructed by China Railway Eighth Bureau and is located at the border of Junlian County in Yibin City, Sichuan Province, and Yanjin County in Yunnan Province. This is a single-hole double-track tunnel with a total length of 7,888 meters, featuring one crosscut divided into two working areas with three construction faces. The longest excavation face measures approximately 4,015 meters, with a total construction period of 43 months.

　　The Junlian Tunnel is a challenging engineering project along the entire railway line, passing through the Datianba anticline area. The geological conditions here are extremely complex, with karst landforms, coal seam gas, rock strata under pressure, and high ground stress, among other adverse geological conditions. As a result, the construction difficulty is significant, with high safety risks.

　　The LanHi intelligent integrated arch anchor trolley adopts an engineering chassis and is equipped with a dual anchor system. The machine features four-wheel steering, four-wheel drive, two-way driving and other functions. Its diesel-electric dual power system supports electric construction and diesel-powered emergency operations. The threearm remote control can meet the requirements for prefabricated arch frame installation, operation of various benching methods and precise positioning adjustment of the arch frame. The arch frame can handle under-excavation and welding operations during installation, and the tunnel itself is very flexible.

　　As of June 12, 2023, the excavation work of the key Junlian Tunnel in the Chongqing-Sichuan section of the Yun-Kun High-Speed Railway has surpassed the milestone of two kilometers, completing 29% of the total length.