After more than three years of hard work by hundreds of builders, on May 6th, the left tunnel of the Yonglian Tunnel of the Lotus Expressway between Ji'an and the Lianhua River penetrated. At present, there are 197 meters of tunnel left tunneling and it is expected to be completed in October this year.
The Yonglian tunnel is 5.1 kilometers in length. The surrounding rock condition of the tunnel is extremely poor. The proportion of surrounding rocks of grade V and above is as high as 70%. The geological conditions are particularly complex, and water inrush and mud disasters occur frequently. The construction is extremely difficult, and the collapse and initial deformation are large. (up to about 0.3 m/day) occurs from time to time, and the safety risk is extremely high. Since the start of construction in March 2011, the participants have adopted a careful construction organization, a reliable construction program, strict quality control, and effective safety management measures to ensure the safe and orderly progress of tunnel construction. In particular, after 15 large-scale water inrush and mud outbreaks occurred in the imported F2 fault zone in 2012, the PMO invites experts to compare and select 4 disposal options for the primary quarantine. Finally, it is determined that the curtain grouting reinforcement method will be used for governance, and Shandong University will be invited. The formation of a consortium with the 15th Bureau of China Railway Construction will manage the geological disasters in the F2 fault zone.