The Research On Structure Mechanical Property Of Deteriorated Shield Tunnel In Erosive Environment

With the rapid advancing of national economic construction and urbanization,the fields of Transportation and Infrastructure have entered the new stage of development.In recent years,as the constructive technology of Tunnel Engineering matures,many complicated tunnel engineering has been constantly emerging,such as,the large cross-section underwater tunnel,the metro engineering on coastal cities.However,during the service process of underwater tunnel,the tunnel structure will be affected by the complex environmental factors,like long-term high water-soil load,erosive environment and operating environment,and then the structural performance of underwater tunnel will degrade with service time,instead of remaining stable.As a result,in order to ensure the structural long-term safety and service performance of underwater tunnel for one-hundred-year service period,depending on the Underwater Running Tunnel of Xiamen’s Metro Line No.2 Project,this paper has discussion and analysis on structural performance deteriorated mechanism.The main research contents and achievements are as follows:1.According to the characteristics of loading and soil-water service environment of underwater shield tunnel,this passage had discussed on deteriorated mechanism of structure performance of underwater shield tunnel,elaborating deteriorated influence factors and deteriorated form of structural performance,and then the deteriorated process of steel and concrete in segment has been analyzed.Based on the influences of soil-water load,erosive environment and coupling interaction,etc,the dendrogram about the structural deteriorated process of underwater shield tunnel has been established.2.Based on the mechanics of composite material and the damage theory,regarding reinforced concrete segment as an equivalent composite material,establishing the calculation method about equivalent elastic modulus of reinforced concrete,and then according to the different material mechanical characteristics of reinforced concrete under compression and tension,the composite mechanics model and the damage evolution equation of reinforced concrete material have been proposed;3.Launching bearing segment indoor accelerated degradation test which points at the bearing performance of deteriorated underwater shield tunnel,and the degradation deformation law under different load has been gotten;then according to the relationship between structural deformation and rigidity,and the definition of damage variable,defining deteriorated damage variable expression of segment under erosive environment,which presented by structural deformation.4.Based on the analysis results about degradation rule of bearing segment,the deterioration evolution equation,steel corrosion equation and degradation equation of structural limit load have been fitted and gotten;besides,According to the composite mechanics model of reinforced concrete,deteriorated composite mechanics model of reinforced concrete has been proposed.5.Based on the(degradation)composite mechanics model of reinforced concrete and deteriorated damage evolution equation of bearing segment,then this passage used finite element simulation analysis software-ABAQUS and had analysis on structural bearing performance of deteriorated tunnel under different soil-water environment,which relied on the Underwater Running Tunnel of Xiamen’s Metro Line No.2 Project.