To ensure the construction safety and determine the
safety redundancy of the envelope structure, a threedimensional
refined numerical model based on the modified Cambridge model is established
based on a metro station foundation pit engineering constructed by covering topdown method in Beijing, China. On the basis of verifying the rationality
of the numerical model by the data measured in the field, the thickness of the
underground diaphragm wall and the floor slab and the diameter of the column
are changed. The influence of the change of the parameters of the envelope
structure on the deformation of the foundation pit and the change of the
redundancy against continuous damage are analyzed. The results show the
following: (1) The coupling effect of the space effect and the pit angle effect
of the foundation pit leads to the distribution rule of the maximum horizontal
displacement value of the underground diaphragm wall: the horizontal
displacement value of the middle underground diaphragm wall of the long side of
the foundation pit is the largest, the horizontal displacement value of other
positions is relatively small, and the horizontal displacement value of the
underground diaphragm wall of the short side of the foundation pit is the
smallest. (2) As the thickness of the underground diaphragm wall and floor
becomes smaller, the horizontal displacement value of the deep layer of the
underground diaphragm wall gradually increases, and the change of the maximum
horizontal displacement value of the underground diaphragm wall increases
exponentially; the surface subsidence value increases gradually, surface
settlement mainly occurs in the range of 2 times the depth of the foundation
pit, and the surface settlement in the range of 2~4 times the depth of the
foundation pit is no longer significant. (3) The stiffness of the floor in the
covering topdown method is greater than that of the
inner support in the opencut method, and the
resistance to deformation is stronger, but the horizontal deformation of the
envelope structure is still affected by the geological conditions and
structural materials to a certain extent. (4) When the thickness of the
underground diaphragm wall and the floor reaches 1.0 m, the redundancy of the
vertical envelope structure tends to be stable, and the continuous increase of
the thickness of the underground diaphragm wall and the floor will not increase
the ability of the structure to resist continuous damage.
LI Pengfei, LI Ze, GE Chenhe, GUO Fei
. Deformation Characteristics and Redundancy Analysis of
Deep Foundation Pit Excavation in Metro Station Using
Covering TopDown Method in Sandy Stratum[J]. Tunnel Construction, 2023
, 43(S1)
: 98
-108
.
DOI: 10.3973/j.issn.2096-4498.2023.S1.012
