Preliminary Study On Seismic Vulnerability Of Typical Drainage Pipelines

The drainage pipeline in China is faced with severe earthquake safety threat,so it is of great practical significance to evaluate the seismic safety risk of the drainage pipeline and check the seismic weak section for pipeline disaster prevention and mitigation.Based on the combined stress value,strain value,seismic damage rate and the number of failure points of the pipeline section under earthquake action,the paper divides the earthquake three-state failure grade of the drainage pipe section and the five-state failure grade of the drainage pipe network,and gives the seismic vulnerability assessment method of the typical drainage pipe.At the same time,the evaluation results of seismic vulnerability of several typical drainage pipelines are calculated,the weak parts of the pipeline are analyzed,and the corresponding countermeasures and suggestions are put forward.The research results of this paper can provide guidance for the seismic disaster risk investigation of drainage pipes in general sites.The main work of the thesis is as follows:1.The research background of seismic vulnerability of drainage pipes and the research status in related fields are systematically described.The seismic damage characteristics of drainage pipes are summarized,and the drainage pipes are divided into continuous drainage pipes and interface drainage pipes according to the interface connection mode.The axial deformation caused by seismic shear wave in continuous drainage pipe is borne by the pipe itself,while the axial deformation of interface drainage pipe is borne by the interface.2.Continuous drainage pipes are divided into continuous rigid drainage pipes represented by continuous welded steel pipes and continuous flexible drainage pipes represented by hot melt PVC-U pipes.The combined stress of drainage pipeline is mainly composed of seismic wave axial stress and earth static pressure stress.According to the different characteristics of the pipe,the three-state failure seismic damage of the pipe section is predicted according to the combined stress or deformation.The criterion of failure grade of continuous flexible drainage pipe section is put forward,and the three-state failure earthquake damage prediction of different continuous drainage pipe section is carried out according to this criterion.3.In order to more intuitively characterize the seismic vulnerability of the drainage pipeline,it is assumed that the combined stress,combined strain,interface deformation,yield strength and ultimate strength of the pipeline material are all subject to lognormal distribution,and the three-state failure probability of the pipeline is calculated,and then the earthquake damage rate per 10 kilometers of the drainage pipeline is obtained.According to the relevant provisions of Earthquake damage Grade Classification of Lifeline engineering,the five-state damage grade of drainage pipeline is determined.4.The three-state failure seismic damage prediction and five-state failure vulnerability analysis are carried out for cement mortar interface reinforced concrete drainage pipe(hereinafter referred to as reinforced concrete pipe)and socket rubber ring interface PVC-U drainage pipe.Taking half wavelength as a standard calculation unit,the seismic damage rate per 10 km of interface drainage pipeline within half wavelength is obtained and the five-state damage judgment is carried out.The effects of shear wave velocity,pipe diameter,wall thickness and buried depth on seismic performance of typical drainage pipeline are discussed.5.In order to verify the practicability of the method proposed in this paper,taking the drainage pipe network of Guangzhou as an example,the basic information of pipe pipe network,pipe diameter,interface form,buried depth and site conditions of the pipe network were counted.Combined with the above methods,earthquake damage prediction and earthquake vulnerability analysis of the pipe network in different pipe sections of Guangzhou were respectively carried out.According to the obtained results,the seismic hazard risk of the drainage network in each district of Guangzhou is evaluated.