LYC Made the First Set of Domestic 11-Meter-Diameter Shield Main Bearing

Good news for being late! On the afternoon of February 25th, Shenjiamen Receiving Well equipment was roaring, which was located in the right line of the undersea tunnel from Zhoushan Shengsi to Dinghai Highway. The “Advance" shield blade, which has 11.7 meters diameter, slowly broke through the hole. This is the first set of 11-meter-diameter level shield main bearing in China. The shield main bearing is a kind of slewing ring bearing. It could undertake the risk of much thinner layer buried shield launching and tunneling, etc. And it successfully completed 1520-meter construction application, which helped the left and right lines of the submarine tunnel all through. The brand of "Made in LYC" is further known in the bearing industry and tunnel construction industry.

The research and devlopment of the shield main bearing is a golden card of "LYC Manufacturing". The shield main bearing, which was used for the "Advance" shield, was jointly researched and manufactured by LYC and China Railway Tunnel Bureau. The diameter of the shield main bearing is 4.8 meters and its weight is about 20 tons. LYC did research about the shield main bearing based on the innovation platform of the State Key Laboratory of Aerospace Precision Bearings and played the leading industry technical advantage of the shield main bearing research and development. For the shield main bearing has characters of high rigidity, high strength and high reliability as well as long life working conditions, LYC innovated the processing method and technology of shield main bearing, and successively overcame technical difficulties of the design method with preload bearing, the floating raceway processing method and the control technology, etc. Especially, LYC did bold innovation and solved the core technical difficulties, such as ultra-wide surface high depth quenching, which restricts the development of the bearing industry. The shield main bearing was successfully rolled out in 2019 and was passed through rigid check by experts and users. The shield main bearing filled the gaps in the development of such kind of bearings in China and realized the real “Made in China” of such kind of bearings.

The minimum burial depth of the shield launching segment for Lujiazhi submarine tunnel is only 6.2 meters. The stratum is dominated by silty clay, which has the characters of high flow plasticity, low bearing capacity, high sensitivity and leads to the floating of shield head loading and the formed tunnel pipe sheet as well as excessive ground settlement. In nearly two years of construction applications, the shield main bearing has undertaken many risks such as high toughness of pvc drainage board for the seawall section, penetration into the tunnel from 3 meters to 4.1 meters, the cutter tool twisting, and blocking silo blocking pump, as well as super shallow buried shield launching and boring, under the drainage board, Lujiachi seawall, twice through the pile-drawing area and other risks. With the trustworthy quality of the shield main bearing, LYC successfully completed the construction application of 1520 meters long in two directions, and made the left and right lines of Lujiazhi Cross-Harbour Tunnel move smoothly.

As is known, LYC self-researched and self-produced the first set of 11-meter-diameter shield main bearing in China, for it adopted advanced technologies and meet the construction needs of a variety of complex working conditions. The shield main bearing is self-contained with preload and seal and has the advantages with high rigidity, high strength, high reliability and long life. Besides, “LYC” shield main bearing can successfully complete the construction application which laid the foundation to further develop larger diameter main bearings and realize the domestic shield machine core components.

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