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 large-diameter 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. Keywords: pipelines, model experiment, finite element, disaster characteristics, validate