Study On Adaptability And Seimsmic Behavior Of Exposed Steel Penstock Through Active Fracture

Pressure water pipes are often used as a pipeline in water diversion projects,Because of its simple structure,high pressure bearing capacity,strong adaptability to deformation and poor geological conditions,low excavation,low investment,and convenient maintenance and inspection,ground exposed steel penstock is widely used in pipeline structures with active fracture.Long-distance water pipelines often pass through fault zones with complex geological conditions,Creep and stick-slip dislocation of active faults have a great threat to structural safety.Therefore,it is very important to study the characteristics of effects of active fracture and the corresponding engineering layout.Laying a plurality of sliding bearings,structure also needs to resist the destruction of seismic loads except the deformation of the faults.In addition,the research on the influence of near-fault ground motion on the safety of exposed steel penstock is relatively lacking at present,and it is worth further discussion.In this paper,with the help of three-dimensional nonlinear finite element numerical simulation analysis softwares like ANSYS,the adaptability and seimsmic behavior of exposed steel penstock under active faults was carried out.The contents are as follows.1.According to engineering experience,two types of structural arrangements for different types of support in the main fault section are proposed.The displacement and stress distribution of exposed steel penstock crossing active fracture under different schemes of creep and stick-slip dislocation are analyzed.Two types of pipelines are well-adapted to fault creep dislocation,and they are severely damaged under stick-slip dislocation.The form of bi-directional sliding bearing and fixed hinged support has better force conditions than unidirectional sliding bearing.2.On the basis of the creep dislocation,the influence of fault-crossing displacement in each direction on the two structures is studied.The relationship between the different compensation methods of the displacement compensation elements and the bearing selection is analyzed.The form of unidirectional sliding bearing compensates displacement by misalignment,and the matching arrangement of bi-directional sliding bearing and fixed hinged support compensates displacement by swing type,which is more adaptable to complex fault displacement.3.When inverted siphon crossing active fault,the boundary conditions keep varying constantly,the structure is likely to encounter earthquake after bearing a certain fault movement displacement throughout the operating phase.By the time history analysis method,dynamic response against seismic loads in initial operation phase and the whole design lifetime were researched.The results prove that the different boundary conditions have little effect on the structural response.However,it is necessary to pay attention to the weakness of the structure like bellows expansion joints,bearing and supporting ring deformation in order to ensure the seismic performance of the structure.4.The measured waves of near-fault ground motion was selected and the response of the over-active fault structure under near-fault ground motion was studied by the time-history analysis.Near-fault earthquakes have long periods and high amplitudes,and it has a great influence on the deformation of structural flexible components such as telescopic joints,bearings.Even if the time of action is relatively short,it also will cause adverse reactions to the structure.These studies provide theoretical support for the prevention of earthquake disasters and ensure the safe operation of the structure.