The temperature inside the Qinling water conveyance tunnel under construction reaches 40 degrees Celsius and the relative humidity is 90%. Working in this environment, with just a little activity, one can sweat profusely. However, the workers here not only cannot go to work shirtless, but also wear heavy bulletproof vests and steel helmets to venture into the tunnel for construction. Because this is a very special tunnel. On July 16th, the national key water conservancy project - the Water Diversion Project from Han to Wei River - was initially put into operation, and the Yangtze and Yellow Rivers successfully "joined hands" in the ancient capital of Xi'an. The beautiful vision of Han River water crossing the Qinling Mountains to moisten the land of Guanzhong has become a reality. Among them, the Qinling Water Diversion Tunnel is a key control project for the entire Han to Wei River Diversion Project. The total length of the Qinling Water Diversion Tunnel is 81.8 kilometers, which is the first time in human history that it has penetrated the Qinling Mountains from the bottom. The maximum burial depth of the tunnel is 2050 meters, which is the deepest in the world among similar projects. The geological conditions in the area where the Qinling Water Diversion Tunnel passes through are extremely complex, and various geological disasters occur in a comprehensive superposition. Among them, the Lingnan TBM section of the Qinling Tunnel from Han to Wei constructed by China Railway Tunnel Bureau is the most difficult and dangerous. The main tunnel of this section is 10 kilometers long and has the characteristics of "three highs, two strengths, and one length", which includes high rock strength, high quartz content, high temperature and humidity, strong rock burst, strong water gushing, and long-distance single head construction. It is the "hard bone" section with the highest construction difficulty, rock burst frequency, and rock strength in the entire project. From the start of construction to the final connection, the Lingnan TBM excavation section of the Qinling Tunnel has always been advancing in a difficult environment of extremely complex geological interweaving, such as strong rock burst, high hard rock, sudden water burst, high temperature and humidity. Especially during the excavation process, thousands of rock bursts have occurred in the excavation section. During the rock burst, the speed of the falling rock fragments is extremely fast, and they hit people at close range with the power of no less than a bullet. In order to avoid occasional rock bursts threatening the safety of operators, damaging mechanical equipment and support systems, operators have to wear bulletproof vests and helmets, and risk being "hit" to clean up rock bursts and flying rocks. During the entire construction process, the builders of China Railway Tunnel Bureau successively overcame world-class tunnel construction difficulties such as rock burst, high temperature, sudden water gushing, and ultra long distance ventilation. They achieved scientific research results in the treatment of sudden water gushing during TBM construction and the construction method of TBM quickly passing through rock burst sections. At the same time, they continuously explored and innovated in extremely hard rock excavation and long-distance single head construction, providing China with strong rock burst We have accumulated valuable technical and management experience in the field of extremely hard rock tunnel construction. The successful completion of the Qinling Water Diversion Tunnel has enabled the early water diversion project from the Han River to the Wei River to be successfully completed. The clear flow of the Han River is crossing the Qinling Mountains, bringing new vitality and vitality to the land of Qinchuan. (New News Agency)