Seismic Safety Evaluation Of Urban Water Transmission Pipeline

China is one of the countries suffered the most severe earthquake disaster in the world. More than 74 percent of the capitals of provinces and more than 50 percent of the prefecture-level cities are located in active earthquake zones with seismic intensity VII or above. The water supply pipelines are the lifeline of a city. Damge of water supply pipelines would have serious influences on the human lives and living quality subjected to earthquakes. Therefore, the research on seismic safety assessment of urban water supply system has a significant theoretical meaning and engineering value.Based on the water transmission pipeline at Dalian, China, using ANSYS to establish finite element model, the response of the buried pipeline is analyzed under seismic waves and permanent ground deformation such as landslides and faults. The contents of the research include:(1) Based on covariance matrix decomposition method, and introducing the transformation relation of response spectrum and power spectrum, the method of non-stationary earthquake motion based on the design response spectrum is improved. According to the seismic design code, the related factors are determined. Meanwhile, an iteration method of power spectrum is suggested to improve accuracy. Using MATLAB, a program is developed to synthesize non-stationary multi-station earthquake ground motions.(2) The nonlinear finite element model of prestressed concrete cylinder pipe (PCCP) is established. The equivalent constitutive relation of PCCP is proposed on the base of numerical simulating tests. Introducing the interaction of soil and buried pipelines, the finite element model of a long-distance transmission pipeline is established. Considering the effects of spatial variation and traveling wave of seismic waves, the dynamic response of the pipeline is performed. The results show that the influence of space variation of seismic wave propagation on long-distance buried pipelines should be taken into account.(3) The influences of soil types, and displacements and lengths of landslides on the response of PCCP subjected to the landslides are studied. The effects of soil types, and the crossing angles and fault displacements on buried PCCP subjected to the faults are researched.(4) Based on above results, the safety assessment of the buried PCCP subjected to seismic waves, landslides and faults is carried. The necessary suggestions are suggested.