Research On Dynamic Response Of Arch-dam-structure Under Thermal-flow Coupling And Its Numerical Simulation

With the implementation of the western development strategy and the adjustment of the country’s power energy structure,70%～80%of China’s hydropower resources in the western region have been paid attention to in energy development,and become the focus of China’s hydropower construction and development.A large number of concrete double-curvature arch dams,over 100 meters high and thin,have been completed.In addition,the western region is one of the most important seismic zones in the Eurasian continent,and the most seismically active region in the country.So it is very important to evaluate the seismic safety of high arch dam scientifically,reasonably and accurately.The aim of this paper is to study the dynamic response of Wudongde Hydropower Station to a 270-meter-high arch dam under earthquake load coupling with gravity,water pressure,temperature and sediment pressure.The main work and results of this paper are as follows:1.Based on the summary of the stress characteristics,stability characteristics and deformation displacement characteristics of the arch dam,the mechanical characteristics and mechanical behavior of the arch dam are studied,which provides a theoretical basis for the seismic performance calculation,natural vibration calculation and dynamic response analysis of the arch dam structure in Wudongde.2.The thermal-structural coupling static analysis of Wudongde arch dam is carried out by ANSYS finite element software,and the stress characteristics of the dam are studied by combining the static method of temperature rise and temperature reduction.The results show that the temperature load has great influence on the deformation of arch dam.At the same time,the combined effect of complex static load has a great influence on the deformation of the dam crest structure,and makes the contact surface between the dam body and the foundation pit produce stress concentration.3.Under the condition of normal water level,the finite element model of dam flood discharge is established,and the flow pattern characteristics of j oint flood discharge of surface and middle holes of the dam body under the condition of normal water level are simulated.The flow pattern and pressure variation characteristics of surface and middle holes in the process of flood discharge are analyzed,and the time-history variation law of pressure of surface and middle holes is obtained.4.Using modal analysis method,taking Wudongde arch dam finite element model as the prototype,the natural vibration characteristics of the dam under different water level conditions are studied.The results show that the foundation frequency vibration of the arch dam under normal water level condition is reduced by 11.1%compared with that under empty reservoir condition,and the foundation frequency vibration of the arch dam under dead water level condition is reduced by 9.9%compared with that under empty reservoir condition.Then the time history analysis method is used to study the coupling effect of complex loads under normal water storage conditions,and the dynamic time history results of stress and displacement are analyzed.Through the calculation,it is found that the stress and deformation of the dam body are very large under the coupling effect of complex working conditions such as flood discharge and earthquake,and the maximum tensile and compressive stress is produced under the coupling condition of flood discharge and earthquake with the increase of normal water storage temperature.The displacement of the top arch of the arch dam is larger,while the displacement of the middle and low sections is relatively small;the basic characteristics of the dam seismic stress are:the dam surface stress is larger,the dam stress is lower.5.In view of the interaction mechanism between RCC arch dam and dam foundation through the cushion,the stress of concrete cushion is simulated under the condition of normal water level temperature rising.The stress characteristics of concrete cushion are studied,and the stress characteristics and failure mechanism of concrete cushion between dam body and dam foundation are analyzed.The variation law of cushion structure stress on height,thickness and width is obtained.