Study On Seismic Reliability Of Urban Buried Pipeline Network Systems

Lifelines include water, gas, heat transmission systems, communication networks, electrical power systems, sewer systems and so on. They are essential for sustaining the normal operation of a community. After a destructive earthquake, the damage of the lifelines and the secondary disaster are more serious in modern cities. Most of lifeline network systems in Chinese cities have not been passed through normal aseismic design, but many big and medium cities may be have the seismic risk background. So, it is necessary to study the seismic reliability of lifeline systems for the needs of earthquake hazard mitigation. This paper presents some methods for solving these problems, which is based on the fact in our country. The main contents includes:1) The seismic damage behavior of the buried pipeline is analyzed by synthesis. Take the breakage of the pipe joints caused by seismic wave propagation as main damage mode; The velocity of seismic wave propagation along the pipelines, soil-pipe interaction, and the correlation between the damage of pipe units are discussed.2) The probabilistic model of seismic damage prediction of buried pipeline is presented. Both the seismic response and the resistance of pipe structures are treated as the random variables, and their statistical characteristics are discussed. Based on the experiment information and engineering application, the allowable deformation and cracked tensile force of the pipe joints are presented.3) The accurate algorithm for the reliability analysis of network is researched. The algorithm is based on constructing the disjoint set of the minimal paths of network system. In which, we use cubic symbol for describing the logic function of a network in well-balanced state, then use sharp-product operation for constructing disjoint minimal path set of network. And a DPS algorithm for finding out the minimal path set is also presented.4) An algorithm for reliability upper bound assessment of large-size network is presented, which is based on the principle of topological classification of node-set; and the lower bound can be also obtained by dual graph of oriented network..5) A fast algorithm for estimate of the network connectivity is presented to evaluate reliability of network by Monte Carlo simulation; and the simulation accuracy and simulation times are also discussed.6) The serviceability of water delivery network in each phase under earthquake is analyzed by simulation method and hydraulics theory. The water leakage model of damaged pipe is discussed, and the relationship between the pipe structural damage andwater leakage is also discussed.7) These presented methods have been programmed and their feasibility and effectiveness have been verified and tested in practice of prediction to seismic damage of water supply network in Zhengzhou city.