Seismic Vulnerability Analysis Of Water Supply System

The Sudden earthquake disasters would result in serious life and property loss inevitabilty.Therefore,for reducing earthquake loss,it is of great significance to make pre-earthquake disaster prediction and post-earthquake emergency response.As an important basic facility system in the lifeline engineering system,the urban Water Supply System(WSS)plays a vital part in people’s production and life.In order to break through the current situation of China’s earthquake disaster prediction and risk assessment,which is at the level of single structure and single system.The research team proposed to carry out the key technology research and software integration development and demonstration of earthquake disaster risk assessment of WSS,which will extend the one-dimensional urban earthquake disaster assessment based on above-ground buildings to the earthquake disaster assessment of multi-dimensional urban system.This research conducted the seismic vulnerability research of WSS,which will provide theoretical basis for earthquake disaster risk prediction and loss assessment.The main research contents and conclusions are as follows:(1)Considering the service age and random corrosion effect of different soil corrosive environment,the corrosion model of buried steel pipe in acidic and alkaline and near-neutral soil environment was established based on the homogeneous Markov process.The accelerated corrosion simulation and tensile failure test of 105 standard steel specimens with five thicknesses were carried out,and the mechanical properties degradation model of steel considering corrosion was established.Furthermore,the mechanical properties of buried steel pipe of different ages in different environments are obtained.The seismic response analysis of buried pipelines with seven different service ages in different soil corrosive environments accomplished,based on the ANSYS finite element platform.Then,the seismic response law of multi-age buried steel tubes under different soil corrosion environments is revealed and characterized,by analyzing the results calculated by ANSYS.The results show that the equivalent maximum strain of buried steel tubes in different soil corrosive environments increases linearly with the increase of service age under different seismic intensity.And the degradation law of pipe’s seismic performance under different environments are significantly different.The degradation rate of pipe seismic performance in acid soil environment is larger,which is about 3-5 times of that in alkaline soil environment.(2)Based on the mechanical properties of buried steel pipe in different soil corrosion environments and ages,the time-varying constitutive model of typical pipeline elements is obtained.The 24 seismic records were selected from PEER database and China seismic network.Then,the incremental dynamic time history analysis(IDA)of typical pipeline units in urban water supply system is carried out,by using peak acceleration and maximum equivalent stress as seismic intensity index and engineering requirement parameters.The time-varying seismic analytical vulnerability models of pipeline units of WSS considering deterioration of durability was established,which include pipeline units in three different soil corrosive environments and four service ages.Furthermore,the corresponding seismic vulnerability curves were drawn.And the seismic vulnerability curves of buried pipelines under three different diameter ranges and four different site types are obtained based on seismic damage statistics.(3)According to the results of seismic vulnerability analysis of pipeline units in WSS,the connectivity analysis of WSS was carried out based on graph theory and Monte-Carlo stochastic simulation.Then the probability of connection between each node of pipeline network and water supply source under different seismic intensity is obtained.Based on the point leakage model of China and the estimation method of leakage area considering failure probability,the flow calculation model of leakage pipeline is established.Combined the Hazen-Williams equation and the law of mass conservation of pipeline transmission flow,the hydraulic analysis of damaged pipeline after earthquake is carried out.And a method to quantify the failure state of node service performance based on the loss ratio of node head is proposed.Taking the repair decision-making coefficient as index,the repair decision-making model with is established considering the difference of regional importance and the service coefficient of water supply nodes.And a functional repair cost model considering pipeline failure state,repair difficulty and repair time is established at the same time.Through the calculation of typical examples,the feasibility,rationality and scientific nature of the model are verified,which is of great significance for pre-earthquake reinforcement and post-earthquake functional quick restoration.