为分析盾构切桩过程中的动力响应特征，以南京地铁10号线盾构穿越群桩工程为背景，结合数值模拟和理论分析，求解盾构切桩冲击荷载诱发的动力响应。同时，在刀盘上安装了振动传感器，对盾构切桩刀盘动力响应进行了监测。主要结论如下：（1）当盾构以5 mm/s左右的推进速度低速切削钢筋混凝土桩基时，推力和扭矩变化较小，且由于桩基为圆柱形，切削断面缓慢增大，因此推力和扭矩表现出明显的滞后性，整个切桩过程中，推力和扭矩峰值约为初始值的1.3倍和1.25倍。（2）仿真结果表明，在刀具多次切削作用下，钢筋切口表现为挤压-拉伸断裂。在冲击荷载作用下，刀盘轴承位置出现多个动力响应波峰，峰值接近0.6g。（3）实测数据表明，在冲击荷载作用下，刀盘轴承位置振动加速度出现连续多次的峰值，间隔约为0.1 s，幅值接近0.5g，实测冲击响应波形与理论解高度相似，两者之间相互验证，该波形可作为多把刀具连续切削钢筋的典型特征。（4）在整个切桩过程中，加速度响应有效值Xrms、峰值XP将显著升高，最大强度约为切削黏土地层时的2倍，且在切桩完成后迅速掉落。相关结论可为盾构切桩状态的识别提供参考。

In order to investigate the dynamic response characteristics during shield cutting pile process, the dynamic response induced by shield cutting pile impact load was solved by combining numerical simulation and theoretical analysis with the background of shield crossing group pile project of Nanjing Metro Line 10. Meanwhile, vibration sensors were installed on the cutterhead to monitor the dynamic response of the shield cutting pile. The results show that: (1) When the shield cuts reinforced concrete pile foundation at low speed of about 5 mm/s, the thrust and torque changes are small, and the thrust and torque show obvious hysteresis owing to the fact that the pile foundation is cylindrical and the cutting section increases slowly, and the peak thrust and torque are about 1.3 times and 1.25 times of the initial value. (2) The simulation results show that the rebar incision presents compression-tension fracture under the action of multiple cuts by the cutter. Under the action of impact loading, multiple dynamic response waveforms appear at the cutterhead bearing position with peaks close to 0.6g. (3) The measured data show that under the impact load, the time domain curve of cutterhead vibration acceleration shows several consecutive peaks with an interval of about 0.1 s and an amplitude of 0.5g, the measured impact response waveform is highly consistent with the theoretical solution and verified with each other. The waveform can be used as a typical characteristic of continuous cutting of steel bars by multiple cutters. (4) During the whole pile cutting process, the acceleration response Xrms, peak XP will be significantly higher, and the maximum intensity will be about twice as high as when cutting clay ground, and it will fall off rapidly after the pile cutting is completed. The relevant conclusions can provide a reference for the identification of shield cut pile status.

TU375.4

国家重点基础研究发展计划（973计划）