The process conversion of PBA method is complex, and
it is easy to cause surface settlement. It is difficult to clear the settlement
law under different stratum conditions, especially under bad geological
conditions such as waterbearing silt formation, which would
cause certain safety hazards to the surrounding environment. As a result, the
distribution of PBA stations in fine silty sand stratum of Beijing Metro is
investigated, the surface settlement laws of PBA station under different
precipitation conditions are analyzed based on monitoring data, and the
calculation and verification are carried out according to the finite element
method. The research results show that: (1) The relationship between occurrence
probability of surface settlement value greater than correspondance and maximum
surface settlement shows a normal distribution; the maximum surface settlement
values of effective precipitation and noneffective
precipitation station are -85.31～-93.29 mm and -126.16～-131.35 mm, respectively, and the
probabilities of the maximum surface settlement value exceeding -60 mm are 53.30% and 74.96%, respectively according
to data fitting. (2) The settlement deformation mainly occurs in the
construction stage of the pilot tunnel and the arch lining, accounting for
about 90%, and the settlement ratio in typical construction stage of top
heading excavation,lower bench excavation,beancolumn
system construction and arch lining construction is about 4∶3∶1∶2. (3) The
settlement trough is consistent with Peck curve, the settlement trough width is
9.82～15.51 m, and the settlement trough width in the
effective precipitation station is 3～5 m wider than
that of the noneffective precipitation station. (4)
The ground loss rate is 0.56%～0.70% generally, and
settlement trough width parameter is affected by precipitation effect
significantly, ranging from 0.51 to 0.89. The conclusions can be used to
preliminarily judge the maximum surface settlement of PBA station．
WU Jingyi
,
YE Xinfeng
,
YU Peng
,
TIAN Tengyue
. Study on Settlement Law of PBA Station of Beijing
Metro in Fine Silty Sand Stratum[J]. Tunnel Construction, 2020
, 40(10)
: 1408
-1416
.
DOI: 10.3973/j.issn.2096-4498.2020.10.003
