Abstract: In response to the key technical problems such as difficult control of drilling accuracy, low efficiency, and easycore rod dropping in high water pressure and water-permeable stratum conditions, based on the Jiangyin Jingjiang Yangtze River Tunnel project, using the three-dimensional spatial positioning method of total station, a local full-scale model test platform was built to simulate the drilling conditions of the leading shield and the following shield. Three types of comparative tests were designed, including different angles of drilling, different hole channel forms, and measures to preventcore rods from falling off. Systematic research on the shield core drilling process was carried out. On the basis of determining the center point of the hole position using the total station, the "four points and one line" positioning method was adopted, supplemented by laser level instrument calibration for the initial positioning of the hole opening pipe, and then the angle was checked using a digital level ruler. At the same time, measures such as reserved hole channel technology and multi-drilling to preventcore rods from falling off were proposed to form a construction technology system suitable for complex conditions. The test results show: 1) By using the "four points and one line" positioning method supplemented by the laser level instrument calibration and combined with the test digital level ruler for angle verification, the deviation of the angle between the hole opening pipe and the horizontal plane can be controlled within ±0.2°, which is less than the design requirement of ±0.3°; 2) Under the 12.5° small angle condition, the machined smooth reserved hole channel compared with no reserved hole channel can increase the drilling efficiency by 631.62% and shorten the drilling time by 91.86%; 3) The surface of the reserved hole channel caused by carbon cutting to remove the inner sealing plate results in a certain degree of attenuation of accuracy and efficiency, but the angle deviation still meets the engineering requirements, and the comprehensive efficiency is much higher than the scheme of drilling through the inner sealing plate; 4) By closing the drilling hole before core sampling and multi-drilling 200 mm, thecore rod recovery rate can reach 100%. This technology was successfully applied to the shield drilling of 363 hole positions in the actual engineering site, and the average drilling efficiency of core sampling was increased from 36 mm/h to 68 mm/h. The research results provided reliable technical and data support for the shield ground-to-ground connection shield drilling in high water pressure and water-permeable stratum conditions under the Jiangyin Jingjiang Yangtze River Tunnel project.

Key words: shield tunnel, underground docking, shield shell drilling, high water pressure and highly permeable stratum, drilling process