On April 28, the right tube of the Guihua Extra-Long Tunnel on the Leshan–Xichang Expressway (hereinafter referred to as the "Lexi Expressway") in Sichuan was successfully holed through, marking major progress in the project's construction and laying a solid foundation for the completion of the entire line.

It is understood that the Lexi Expressway (from Mabian in Leshan City to Zhaojue in Liangshan Prefecture) is the 7th of the 8 longitudinal lines in the Sichuan Provincial Expressway Network Plan. The route starts at Minjian Town, Mabian Yi Autonomous County, Leshan City, connecting to the Mabian branch of the Renmu New Expressway, passes through Leibo County and Meigu County in Liangshan Prefecture, and ends on the south side of Zhaojue County, connecting with the Xichang–Zhaotong Expressway. With a total length of 151.753 kilometers and a construction period of 5 years, it is the first expressway to penetrate deep into the heartland of the Greater and Lesser Liangshan Mountains.

The Guihua Tunnel of the Lexi Expressway is invested in by Sichuan Expressway Company of Shudao Group and constructed by Sichuan Road & Bridge Group. The right tube of the Guihua Tunnel is 4,913 meters long and is located in the upper half of the 64-kilometer long steep longitudinal slope section of the Lexi Expressway in the Hengduan Mountains. The elevations of the inlet and outlet are 1,766 meters and 1,884 meters respectively, with an average longitudinal slope of 2.44%. It successively passes through the Leibo 212 State-owned Forest Farm and the Mabian Dadu River Dongfeng State-owned Forest Farm, where national first-class key protected wild plants, mainly Davidia involucrata (dove trees), are densely distributed. The area also has a highly variable microclimate, with rainfall on 270 days per year and a snowfall period of more than 3 months in winter. The construction environment is harsh, and the requirements for environmental protection and soil and water conservation are relatively high.

The Guihua Tunnel is constructed by excavating from both the inlet and outlet ends toward each other, passing through 2 fault zones totaling 880 meters and 20 karst areas, with a maximum single mud inrush volume of 500 cubic meters. At the inlet end, a 200-meter section encountered a through-type dissolution conduit, causing roof collapse 7 times; the outlet end is constructed on an adverse slope, with a maximum daily water inflow of 10,000 cubic meters. The construction conditions are harsh, safety risks are high, and prevention and control are difficult.

During construction, all participating parties used large drones to conduct ultrasonic geophysical prospecting of the ground in the tunnel area, invited experts for 8 on-site consultations, promptly adjusted and optimized the design and construction plans, and deployed intelligent mechanical equipment including 4 intelligent arch-anchor trolleys, 2 double-arm rock drills, and 4 wet-spraying robotic arms, realizing a new model of intelligent construction with fewer workers in the tunnel. At the same time, systems such as work safety and tunnel shift supervision management were strictly implemented, achieving zero work safety accidents.

The holing-through of the right tube of the Guihua Tunnel has achieved the longitudinal connection between the two work zones of the Lexi Expressway S1-8 project. The time for the project department to reach the inlet end of the Guihua Tunnel has been shortened from 90 minutes to 20 minutes, greatly improving the efficiency of project management and the comprehensive allocation of resources between the two work zones, and providing a fast channel for transporting construction materials and equipment for the last tunnel in the 40-kilometer uninhabited area of the Lexi Expressway, the Dafengding Tunnel.