On June 21, the Panxing Railway project—the last project in Guizhou Province's goal of "high-speed rail in every city"—achieved a major milestone: the No. 1 drainage tunnel of the Tuole Tunnel, constructed by China Railway 11th Bureau Group, was successfully holed through, laying a solid foundation for subsequent construction.

The Tuole Tunnel has a designed total length of 13,317 meters, of which the No. 1 drainage tunnel is 4,901 meters long. The main challenges of this tunnel are coal and gas, karst, and the contact zones between soluble and insoluble rock. During construction, it is necessary to pass through one coal seam; at the same time, the tunnel passes through a karst-dissolved fracture zone where the surrounding rock is extremely broken, making it a Class I high-risk tunnel on the entire line.

According to Du Song, the on-site person in charge of the Panxing Railway for China Railway 11th Bureau Group, the holing-through of the No. 1 drainage tunnel of the Tuole Tunnel will effectively solve the difficulties of construction drainage and ventilation between the working sections, creating favorable conditions for the comprehensive advancement of tunnel construction. At the same time, it facilitates the organization of construction logistics for the key route: on the one hand, it clarifies the geology for excavation of the main tunnel bore, and on the other hand, it can increase tunnel ventilation and improve the construction environment. It will be permanently retained as a drainage tunnel after the railway is put into operation.

Yang Jianxun, a senior engineer at the Panzhou Command of the Shanghai-Kunming Company, introduced that during construction, in response to prominent risks such as gas and karst in the Tuole Tunnel, we strictly urged the construction unit to implement management plans in terms of ventilation, monitoring, fire control, and emergency response. At the same time, we used advanced horizontal drilling, transient electromagnetic methods, ground-penetrating radar, and other means to carry out advanced geological forecasting, promptly identifying adverse geological conditions ahead and taking targeted measures in advance, thereby ensuring safety during construction.

It is reported that after the Panxing Railway is completed, it will be of great significance for southwestern Guizhou and surrounding areas to integrate into the national high-speed rail network, promote regional economic integration, accelerate the construction of a new highland for inland opening-up, and speed up the leapfrog economic and social development of ethnic minority areas.