To explore the evolution patterns of pore pressure
during the excavation of a deep tunnel and determine the longitudinal value of
a threedimensional seepage calculation model, a threedimensional finite element model of a deepburied
long tunnel is established with the monitoring section as the center. First, a
scheme, in which the tunnel is excavated through one time, is adopted and the
timehistory of pore pressure dissipation during
excavation is studied. Then, the drawdown of the water table and the evolution
of pore water pressure are investigated with excavation process. To construct
an entire curve of pore water pressure evolution on the monitoring section, the
influence scope of the tunnel face in the process of excavation is explored.
Finally, the suggestions for the longitudinal value in threedimensional seepage numerical model and the setting of monitoring
section are given. The results show the following: (1) The stepped excavation
method can better reflect the mechanism of pore water pressure evolution than
the onetime excavation method. (2) When the excavation
distance is 22.5〖WT〗D, where refers
to the tunnel diameter, the forward influence scope of the tunnel face
gradually reaches 〖WT〗80D. 〖WT5《TNR》〗(3) When the tunnel face goes across
the monitoring section and the excavation distance reaches 〖WT〗155D, 〖WT5《TNR》〗the backward influence scope of the tunnel face gradually reaches 〖WT〗72D. Therefore, a large longitudinal model range is required, and the
monitoring section should be outside the forward and backward influence scope
of tunnel face, which should be more than 〖WT〗174.5D.
YE Yanzhong, ZOU Debing, WANG Hanhui, SU Kai
.
Evolution of Pore Pressure Around Tunnel Face and
Influence of Longitudinal Value
of ThreeDimensional Seepage Calculation on It During Construction of a Water Conveyance Tunnel With Rich Water
[J]. Tunnel Construction, 2023
, 43(S2)
: 230
-236
.
DOI: 10.3973/j.issn.2096-4498.2023.S2.026
