为获得基于试验的盾尾油脂渗漏参数以及盾尾密封渗漏模型，通过油脂剪切试验、自制单元体油脂逃逸试验分别对油脂本构关系以及盾尾刷阻力系数进行确定。根据多孔介质理论对盾尾刷钢丝束与管片接触部分进行简化，建立盾尾密封系统数值模型。通过自制大尺度盾尾密封模型试验对外界泥水击穿盾尾密封系统过程中各油脂腔压力以及击穿时间进行采集，并与数值模拟结果进行对应。得出以下结论： 1）当围压超过130 kPa时，油脂的剪切屈服应力基本不发生改变，油脂本构关系可按照宾汉姆流体进行拟合。2）在外界泥水压力的作用下，油脂团从盾尾刷钢丝束与管片外壁接触处发生逃逸，盾尾刷对油脂的阻碍作用变化主要取决于盾尾刷钢丝束与管片的贴合长度。3）根据安装的压力传感器，单道油脂腔压力与外界泥水压力基本同步变化，多道油脂腔压力沿盾构掘进方向压力逐级下降。4）根据单腔以及双腔工况模拟结果，单腔的击穿压力为0.7 MPa，击穿时油脂腔含水量达到34%，双腔的击穿压力为1.3 MPa，击穿时第1道油脂腔含水量达到38%，第2道油脂腔含水量达到22%。模拟结果显示击穿压力下的击穿时间与试验结果相匹配，验证了油脂本构关系以及盾尾刷阻力系数的合理性。
The authors develop a
shield tail grease leakage model and derive key parameters through several
experiments. The grease constitutive relationship and shield tail brush
resistance coefficient are determined through grease shear tests and custom-designed unit grease escape tests. Based on these experiments, the
authors develop an experimentally derived set of shield tail grease leakage
parameters and a corresponding leakage model. In addition, the contact
interaction between the shield tail brush wire bundle and the segment is
simplified using the porous media theory, consequently establishing a numerical
model of the shield tail sealing system. Finally, the pressure and breakdown
time of each grease chamber during the external slurry breakdown of the shield
tail sealing system are determined by conducting a self-made large-scale shield tail sealing model
experiment, and the results correspond with the numerical simulation results.
The primary conclusions of this study are as follows: (1) When the confining pressure
exceeds 130 kPa, the shear
yield stress of the grease becomes relatively stable. The constitutive
relationship of the grease can be fitted according to the Bingham fluid model.
(2) Under external slurry pressure, the grease escapes from the contact
interface between the shield tail brush wire bundle and the segment′s outer wall. The obstruction effect of the shield tail brush on
grease is primarily dependent on the length of the bond between the shield tail
brush wire bundle and the segment. (3) Data from pressure sensors indicate that
the pressure in single grease chambers synchronously reflects the external
slurry pressure. However, pressures across multiple grease chambers gradually
decrease along the shield tunneling direction. (4) Simulation results of single- and double-chamber scenarios reveal
distinct behaviors. The breakdown pressure of a single chamber is 0.7 MPa, with
the water content of the grease chamber reaching 34% during breakdown. For the
double-chamber scenario, the breakdown pressure
increases to 1.3 MPa, with water contents of the first and second grease
chambers reaching 38% and 22%, respectively, at breakdown. The simulated
breakdown time under breakdown pressure closely aligns with the experimental
values, thereby validating the accuracy of the grease constitutive relationship
and the resistance coefficient of the shield tail brush.
