Study On Dynamic Response Of Yinhanjiwei Water Transfer And Distribution Project Across The Northern Margin Of Qinling Mountains

With the urgent need of implementation of the western development strategy and the"One Belt,One Road" construction,the development and construction of the western mountainous areas is becoming increasingly urgent.The Loess Plateau in the Northwest China has high mountains and deep valleys,and the complicated tectonic background and topography.In the process of construction,it is inevitable to build a large number of tunnels in this area,and the construction of tunnels and underground projects will inevitably cross the active fault section.When the tunnel or pipeline engineering passes through the fault zone,it will directly bear strong compression or pulling due to the dislocation of the upper and lower walls of the fault zone,resulting in the deformation of the linear structure of the tunnel and catastrophic damage.The tunnel as a traffic line,lifeline engineering,once the damage occurs,the consequences are unimaginable.Therefore,the research on the failure mechanism of tunnel crossing active fault is undoubtedly of great scientific research and practical engineering application value.The article is based on the project "impact assessment and response technology research on active faults in the northern margin of Qinling Mountains of the second phase project of water diversion from Hanjiang to Weihe",taking the fault zone in the northern margin of Qinling Mountains as the research area.Through data collection and field surveys in this area,the three-dimensional spatial relationship between the water transmission and distribution pipeline and the fault at the northern margin of the Qinling Mountains is determined.Based on the site prototype,the similarity relationship of the model test was determined,and then the large-scale shaking table model test of the cross-fault water pipeline across the fault fracture zone of the northern edge of the Qinling Mountains was carried out,Combined with the analysis and verification of FLAC3D numerical simulation software,analyze the dynamic response characteristics of the cross-fault pipeline and the model structure and the pipeline catastrophe mechanism,Propose an anti-fault-breaking scheme for cross-moving fractured pipelines.The main research contents and results of this paper are as follows:1.The geological engineering conditions of the study area were determined by collecting data and combining with field investigation.The similarity ratio of the test model is determined by taking the section of the water diversion pipeline from Hanjiang to Weihe across the fault zone in the northern margin of Qinling Mountains as the prototype.The generalized model of shaking table test is established based on similarity theory.Through the demonstration of similar model materials,the similar materials and ratio of surrounding rock,tunnel and fracture model are obtained respectively,and the layout principle and location distribution of sensors in model test are determined.The seismic wave and loading scheme are selected to load the model structure under different working conditions.2.Large scale shaking table tests were carried out to analyze the dynamic response characteristics and deformation failure modes of the pipeline under different seismic waves and different ground motions,including the acceleration response law of the soil pipe structure,the earth pressure response law and the deformation characteristics of the pipeline.The dynamic response characteristics of soil pipe structure under ground motion are revealed.3.FLAC3D numerical simulation software is used to analyze the dynamic response of the pipeline crossing the northern margin of Qinling mountains under the action of ground motion,In order to study the dynamic response mechanism of the model structure under different ground motions,the pipe monitoring points are set in the model structure to monitor the acceleration response,pipe deformation and structural displacement of the soil pipe structure.4.The results show that the acceleration amplification coefficient in the model structure also shows elevation amplification effect and fault zone amplification effect.The acceleration response is the strongest in the fault zone,and gradually decreases from the center of the fault zone to both sides.The displacement of the pipeline also presents the same rule,which reaches the maximum near the fault zone.