The Damage Identification Method Of Shield Tunnel Based On Time Series Model

In recent years,with the development of the city and the increase of traffic pressure,more and more cities began to develop rail transit.In 2015,there were 39 cities in construction or planning construction of rail transit in China,estimated that by 2020 the number of the city owning rail transit will reach 50,and urban rail transit is expected to achieve the scale of nearly 6000 km by 2020.The metro is the main construction of urban rail transit,so it carries the heavy responsibility of the urban transportation and the safety of construction and operation becomes particularly important.Thus health monitoring and damage detection of metro shield tunnel also became an important issue.The damage identification based on the time series analysis is a nondestructive detection method and it has been continually perfected and developed in recent years.It's suitable to adopt this method as the shield tunnel is an overlong and liner civil engineering structure and.And it's subjected to stable metro train load,thus the acceleration response will be stable.The specific research work is shown as follows:1.A brief introduction of the basic theory of time series analysis is carried out and based on it the relationship between structural vibration and time series model is theoretical deviated.ARMA model is adopted to fit the acceleration response.Because the time series model parameters contain the structural characteristics,three damage indicator based on them are adopted.2.A finite element analysis model of shield tunnel is built by ANSYS software.Damage is simulated by changing the elasticity modulus of the shield model and then the acceleration corresponding signal of shield tunnel finite element model bearing the train moving load is collected.Follow by it damage identification is conducted and the result says this method based on ARMA model have a good performance on damage identification.3.in addition,laboratory scaled model tests are conducted and the acceleration response under different damage cases are collected.The damage location can be correctly identify and this results further verify the feasibility of the method proposed.