By Lynda Myer
Following 821 days of hard work, on May 30, Baiyunshan Tunnel, which is the longest tunnel over the whole Chengdu-Zigong-Yibin High-speed Railway contracted by CHINA RAILWAY 12TH BUREAU GROUP CO. LTD, had a smooth holing-through, laying a solid foundation for the opening of the whole Chengdu-Ziyi High-speed Railway.
Located at the national shale gas demonstration area, the Baiyunshan Tunnel has a total length of 13,340 m, and the surrounding rocks of over grade Ⅳ and Ⅴ accounting for 81.9% and altogether under passing through 7 reservoirs and 5 coal mining areas, with natural gas and coal gas superimposed with each other, resulting in extremely high construction safety risks.
Meanwhile, the normalized safety measures for gas tunnels and rationally arranged ventilation equipment according to the ventilation distance, strictly following the principle of one being active and the other standby to set up ventilation fans and ventilation belts, establishing intelligent hot standby control system to realize instant switchover of active and standby fans, have been implemented strictly by the builder in order to ensure that the gas concentration was always within the safety limit during construction. At the same time, the gas concentration in each operation area is mastered in real-time through automatic monitoring system and artificial gas monitoring system, and the data is associated with the fan control system to realize the dynamic regulation of ventilation volume.
In order to resolve the cross-interference contradictions, which have been faced due to the adverse geology during the construction process, and finally complete all tunneling tasks safely and smoothly, the contractor innovatively applied large mechanized supporting construction method, and formed production lines of advance geological forecast and advance prereinforcement for different types of surrounding rocks by means of information technology, and at the same time, optimized and intelligently modified the organization of engineering equipment and production lines.
As an important part of the Beijing-Kunming Railway, a part of China’s eight longitudes and eight latitudes high-speed railway network, the Chengdu-Zigong-Yibin High-speed Railway is a2lmost 60 kilometers and is also the first southbound high-speed railway channel with a speed of 350 km/h in Sichuan Province. Once opened to traffic, this line is of great significance to the opening of the line from Chengdu to Yunnan as well as the connection to the railway system in the important economic zone of the Pearl River Delta.
