On February 6, after more than five years of arduous efforts by builders from the Fourth Company of China Railway 17th Bureau Group under China Railway Construction Corporation, the Xianghe Tunnel on the Guangtong-Dali Railway, part of the China-Myanmar international railway corridor and known as a “museum of unfavorable geology,” was fully bored through.
The Xianghe Tunnel, with a total length of 10,220 meters, is located at the border between Dali and Xiangyun. Its maximum burial depth reaches 705 meters, and it passes through nine large mountain fault fracture zones. It is known for “complex geological conditions, frequent changes in surrounding rock, developed groundwater systems, and frequent water and mud inrushes.” Construction was extremely difficult, and it was the last tunnel on the Guangtong-Dali Railway to be bored through.
　　During construction, the project followed the construction principles of “short advance, weak blasting, and strong support,” adopted measures such as initial shotcrete, strong anchoring, and locking feet, and used new technologies and new processes to overcome difficulties such as large water inflow, many soft-soil interlayers, and rapid changes in surrounding rock. This effectively avoided more than 20 major and minor dangerous situations and achieved the safe breakthrough of the Xianghe Tunnel, the last “hard bone” of the Guangtong-Dali Railway. According to Li Haibin, the project's chief engineer, in his 18 years of railway engineering work, the Xianghe Tunnel was the most difficult one to construct. The tunnel's average daily water inflow reached more than 110,000 cubic meters, and the cumulative water inflow could fill 100,000 standard swimming pools. When this kind of geology encounters water, it forms a muddy quagmire, and they literally carved out a tunnel from such a muddy quagmire.
　　The Guangtong-Dali Railway capacity expansion and renovation project is 175 kilometers long, with a target speed of 200 kilometers per hour for passenger trains and a bridge-tunnel ratio of 63%. It is an important component of the western line of the Trans-Asian Railway and the Yunnan-Tibet Railway, and is a national first-class double-track electrified railway. The Guangtong-Dali Railway connects eastward to the Kunming-Guangtong Railway, northward to the Chengdu-Kunming Railway and the Dali-Lijiang Railway, and westward to the under-construction Dali-Ruili Railway and Dali-Lincang Railway. After the railway opens, intercity trains are expected to operate between Kunming and Dali, with a travel time of only about 2 hours, about 4 hours less than at present. It is of great significance for strengthening the transport capacity of the road network in western Yunnan, building Yunnan's outbound corridors, driving economic and social development in western Yunnan, and promoting Yunnan's active service to and integration into the national “Belt and Road” initiative.