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.
LI Dawei
,
ZHONG Xiaochun
,
LIU Chang
,
SHEN Guili
,
ZHONG Jianling
,
HUANG Siyuan
. Numerical Model and
Validation of Leakage for Multi-Chamber Sealing System of a Shield Tail Brush[J]. Tunnel Construction, 2025
, 45(2)
: 304
-314
.
DOI: 10.3973/j.issn.2096-4498.2025.02.006
