Under the Qilian Mountains in early spring, there is a snow-capped northern scenery. Right now, at the construction site of Qilian Mountain 2# tunnel shaft at an altitude of 3,733 meters on the north slope of Ningchuang Pass, with the roar of machines, the workers on site are busy in their respective positions in an orderly manner, preparing for the next Qilian Mountain 2# tunnel ventilation shaft The construction of the main structure is fully prepared.

Qilian Mountain 2# Tunnel is one of the control projects of the highway project of the Ningchuang Pass to Ketu section of the National Highway 569 from Mandela to Datong Highway, and it is also the first high-gas long highway tunnel in Qinghai Province. In order to effectively solve the ventilation problems of extra-long tunnels and high-gas tunnels during construction and operation, the tunnel is designed with a ventilation scheme of full-jet longitudinal ventilation + special shaft for smoke exhaust. Air and ventilation function, send the fresh air from the outside into the tunnel, and at the same time discharge the gas in the tunnel from the wellhead to form a circular breathing system.

The tunnel shaft is set on the left line of the main tunnel, with a depth of 218m. The section of the shaft adopts a circular section with better structural stress, and the inner diameter is 5.4m. According to the design geological survey results, the formation lithology in the shaft construction area is Devonian strongly weathered sandstone interbedded with mudstone. Due to the influence of faults, the stability of the shaft wall during shaft construction is extremely poor, and well collapse is prone to occur. In order to ensure that the shaft meets the quality and safety requirements during the construction process, the project took multiple measures. First, strengthen the construction process control, prepare various special plans for shaft construction, ventilation, toxic and harmful gas monitoring, etc., and implement them strictly according to the special plans during the construction process. Ensure that construction safety and quality are under control. The second is to strictly control the quality during construction, strengthen the management and control of raw materials entering the site, eliminate the phenomenon of using without inspection, take measures to ensure the traceability of materials used, strengthen refined management, increase the strength of arch processing and installation process improvement, and adopt The total station ensures the installation accuracy of the steel frame, etc. The third is to tighten the production safety valve, do a good job of safety training and disclosure, and carry out the anti-overturning calculation of the entire derrick hoisting system in terms of technology, strictly carry out the wire rope pull-off test, non-destructive testing at the hook head and pin shaft, etc., and carry out advanced geological prediction of the shaft at the same time and monitoring measurement work.

In order to fully and accurately implement the provincial traffic control group's decision-making and deployment on promoting high-quality development of project construction, fully implement the requirements of refined management, lean operation, and meticulous service management promotion activities, and continue to accelerate the progress of tunnel construction, the project office implements a daily scheduling management mechanism , to conduct a comprehensive review and check on the establishment of the shaft prevention mechanism, risk control, quality and safety, emergency management, standardized construction, evaluation and innovation, and smart construction site construction to ensure that the construction of the ventilation shaft of the Qilianshan 2# tunnel is progressing in an orderly manner. Up to now, 90% of the temporary construction of the Qilianshan 2# tunnel shaft has been completed, and the construction of the main lock and the lock ring of the shaft has been completed.Editor/XingWentao