Influences of subway tunneling on disaster of overlying rainwater and sewage pipelines

Abstract

Tunneling can cause the disaster of surrounding pipelines,
thereby inducing serious consequences, such as road collapse.
Existing relevant studies mainly focus on small-diameter pressure
pipelines, while explorations on disaster characteristics of largediameter overlying rainwater and sewage pipelines (ORSP) with
high rigidity and strength as well as socket are rare, and the
research methods of disaster characteristics of small-diameter
pressure pipelines are mostly a combination of theoretical and
experimental analyses, or a combination of theoretical and finite
element analyses. In order to study the disaster characteristics of
large-diameter ORSP during tunneling, the settlement and stress
features of pipelines were evaluated through a model experiment
of the pipe-tunnel orthogonal program, and influences of
tunneling on the disaster of ORSP were discussed. Then, nonlinear
simulation of the model was performed by finite element analysis.
Numerical results are compared with model experiment and
theoretical calculation results, and main indexes that influence
the disaster characteristics of ORSP were examined. The results
demonstrate that the settlement curve of ORSP conforms to
Gaussian distribution, and the height of subsider increases with
the increase in excavation procedures and stabilization time,
thereby reaching 19.5 mm. Stress on ORSP is symmetric around
tunnel centerline. The bottom is pressed slightly, while the top is
stretched locally. Reliability of numerical model and theoretical
calculation is validated by the finite element analysis. Stress
ranges between −545-59kPa, indicating that most positions of
top and bottom of ORSP bear low pressures. The settlement of
ORSP according to parameter analysis decreases with the increase
in pipe-tunnel net distance (l) and inner diameter of pipeline (d).
The settlement of ORSP becomes stable When l/D>3 (D is tunnel
diameter) and d/l>0.24. The stress of ORSP gradually decreases
with the growth of l and d. Conclusions in this study can provide
theoretical references for ORSP protection measures in subway
tunnel constructions.