为实现软流塑地层盾构连续穿越大直径钢筋混凝土群桩，以绍兴地铁 2 号线切桩工程为例，从盾构机的 选型、参数控制、切混凝土及切钢筋机理、刀具磨损等方面分析了撕裂刀对钢筋混凝土桩基的切削效果。主要结 论为：1) 采用 MJS (metro jet system，全方位高压喷射注浆)地层预加固技术和 3 层刀布置技术顺利完成软流塑 地层盾构切桩任务；2)“慢推速、中转速、小扭矩、严控浆、早补强、勤量测”盾构施工控制准则，适宜软流塑 地层盾构磨桩施工；3) 钢筋存在剪拉、弯拉和纯剪 3 种破坏形式，剪拉和纯剪破坏各占 47%和 25%，满足预 期目标；4) 钢筋主要缠绕在中心区刀梁孔洞处和 R≤2 025 mm 范围内，长度以小于 3 m 居多，以弯拉破坏为 主；5) 刀具破损率及磨耗量均随轨迹半径增大而增加，2 500 mm 为刀具磨损陡增的临界值；6) 基于现有刀具 磨损状态，预计可继续切削 1 根直径 1 m 全断面工程桩。

The case of Shaoxing Subway Line 2, a shield tunneling project cutting through large-diameter reinforced concrete pile groups in soft fluid-plastic stratum, is systematically analyzed, regarding shield tunneling machine selection, parameter control, cutting mechanism of rebar and concrete, and tool wear. The main conclusions are summarized as follows: 1) The implementation of ground improvement by MJS (Metro Jet System) technique and the arrangement of three-layers tearing cutters facilitate the completion of multiple pile cutting. 2) The principles of “low driving speed, medium rotating speed, small shield torque, strict grouting, advanced strength supplement, and frequent measurement” are suitable for the control of shield tunneling in soft fluid-plastic stratum. 3) Three failure forms of rebar are observed, i.e., shear-tension, bending-tension, and pure shear, and the failure modes of shear-tension and bending-tension are dominant, accounting for 47% and 25%, respectively. 4) Rebars, with a radius of R≤2025 mm, are wrapped around the shield disk near the blade holes of shield center, and the engths of most of these rebars in the bending-tension mode are less than 3 m. 5) The cutter breakage rate and dimension increase significantly with the increase of track radium, which shows some critical increments at a track radius of R=2500 mm. (6) Based on condition of the tearing cutters, the shield is still able to cut one more full section engineering pile with a diameter of 1 m.

U231；U455.43

中国科学院重点部署项目(ZDRW-ZS-2021-3-1)