Design and construction of prefabricated installation of large diameter pipeline in shield shaft

In the Heilongjiang shield tunneling project of the China–Russia Eastern Gas Pipeline, 5-time-diameter hot-bending bends with a diameter of 1 422 mm and a wall thickness of 39 mm needs to be installed in the shaft, but the conventional sectional welding method for installation in the shaft can't be adopted. The technical scheme for installing large diameter pipe in shield shaft was designed. In this scheme, the automatic welding process was used on the ground, to weld the hot-bending bends and straight pipes in the shield shaft to form a big S-bend, which was then hoisted and installed in position by the "through-hole method". Visual inspection on all welds was qualified, and through the X-ray and ultrasonic inspection, the nondestructive testing on 16 welded joints met the requirements of the standards both in China and Russia, indicating they were all qualified. The successful application of this technology has realized one-step hoisting in position of large diameter pipelines and bends in the shaft, and solves the installation technical problem that full automatic welding cannot be used in narrow space. It can provide reference for the installation of large diameter pipelines in such shields and pipe jacking shafts in the future.