基于绍兴地铁2号线切桩工程，为实现软流塑地层盾构连续穿越大直径钢筋混凝土群桩，从盾构选型、参数控制、切混凝土切钢筋机理、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，主要结论如下：（1）采用MJS地层预加固技术和3层刀布置技术圆满完成软流塑地层盾构磨桩任务；（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≤2025mm范围内，长度以小于3m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，2500mm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1m全断面工程桩。

For the aim of shield cutting large-diameter reinforced concrete piles in soft fluid-plastic stratum, the subject based on the Shaoxing subway line 2 to analyze shield type selection, parameter control, mechanism of cutting rebar and concrete, and tool wear. The main conclusions as follows: (1) MJS construction method and three layers tearing cutter method finished the job of pile cutting. (2) the principle of pile cutting parameters control with “low propulsion speed, medium rotate speed, small shield torque, strict grouting, advanced strength supplement, frequent measurement” is suitable for soft fluid-plastic stratum. (3) Three forms of rebar destruction are shear-stretch, bend-stretch, and pure shear, and the pile cutting target had achieved of shear-stretch and bend-stretch destruction form occupy 47% and 25% respectively. (4) Rebars were convolved the shield disk where the blade holes of shield center and tracks of radius R≤2025mm, and most of these rebars lower than 3 meters with bend-stretch destruction. (5) R=2500mm is critical track of cutter destruction, and cutter breakage rate and dimension will increase significantly with the increasement of track radium. (6) Based on the tearing cutter states, only one full section engineering pile can be cutted.

U455.43