Abstract: The shield launching and receiving is one of difficulties for large crosssection horseshoeshaped shield tunnel construction. In this paper, the key construction technologies of shield launching and receiving of large crosssection horseshoeshaped shield used in Baicheng Tunnel on Menghua Railway are studied and summarized. The key technologies adopted include: (1) In the shield launching stage, the cost of reaction frame production and dismantling and the amount of original negative ring pipe can be reduced by replacing traditional shield reaction frames by strengthened open hole, which helps to shorten the construction time and save the cost. (2) The bottom of launching base is evenly laid with bean gravel to reduce the backfilling time of hollow between launching guide hole and pipe after the shield enters undisturbed soil. (3) In shield launching stage, the arch steel frame is innovatively adopted to replace the traditional launching endwall structure, which reduces the construction amount of launching ancillary facilities and shortens launching preparation time. (4) In receiving stage, the base is combined with the endwall to reduce the security risk of the shield machine receiving in the weak stratum. (5) The launching and receiving positions of shield are optimized to make full use of the main operation surface of shield tunneling and open tunnel without interfering with each other, which would realize better economic and safety benefits.

Key words: Baicheng Tunnel, large crosssection horseshoeshaped shield, launching, receiving, open hole strengthening